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dart-sdk/pkg/analyzer/messages.yaml
Parker Lougheed 061396f38d [analyzer] Add back removed diagnostic messages 
It adds them back and specifies `removedIn: "3.2"` to prevent generation of error codes.

Fixes https://github.com/dart-lang/sdk/issues/53120

Bug: https://github.com/dart-lang/sdk/issues/53120
Change-Id: Icc6e861f317b582d15d463867f08ba70ffee9f2b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/319382
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Brian Wilkerson <brianwilkerson@google.com>
2023-08-09 16:53:36 +00:00

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# Copyright (c) 2021, the Dart project authors. Please see the AUTHORS file
# for details. All rights reserved. Use of this source code is governed by a
# BSD-style license that can be found in the LICENSE file.
# This file is organized as a two level map, where the outer key corresponds to
# the name of an analyzer error class (e.g. CompileTimeErrorCode), and the inner
# key corresponds to the name of a static variable in that class, describing a
# single diagnostic message. Ideally, each entry contains three parts:
#
# 1. A message template (problemMessage).
#
# 2. A suggestion for how to correct the problem (correctionMessage).
#
# 3. User-facing documentation for the problem (documentation).
#
# A message shouldn't indicate which kind of diagnostic it is, for example,
# warning or error. This is implied by the analyzer error class. For example,
# all entries in `StaticWarningCode` are warnings.
#
# See the file [lib/src/fasta/diagnostics.md] for more details on how to write
# good diagnostic messages.
#
# A message used for internal errors should have key that starts with
# "InternalProblem". This way, UX review can prioritize it accordingly.
#
# Eventually, we'd like to have all diagnostics in one shared location. However,
# for now, we have analyzer error codes and CFE error codes in separate files.
# See `pkg/front_end/messages.yaml` for the CFE error codes.
#
# ## Parameter Substitution in problemMessage and correctionMessage
#
# The fields `problemMessage` and `correctionMessage` are subject to parameter
# substitution. When the compiler reports a problem, it may also specify a list
# of values to be substituted into the message. Parameters are declared using
# placeholders of the form `{INTEGER}`, e.g. `{0}` is the zeroth parameter.
AnalysisOptionsErrorCode:
INCLUDED_FILE_PARSE_ERROR:
problemMessage: "{3} in {0}({1}..{2})"
comment: |-
An error code indicating that there is a syntactic error in the included
file.
Parameters:
0: the path of the file containing the error
1: the starting offset of the text in the file that contains the error
2: the ending offset of the text in the file that contains the error
3: the error message
PARSE_ERROR:
problemMessage: "{0}"
comment: |-
An error code indicating that there is a syntactic error in the file.
Parameters:
0: the error message from the parse error
AnalysisOptionsHintCode:
STRONG_MODE_SETTING_DEPRECATED:
problemMessage: "The 'strong-mode: true' setting is deprecated."
correctionMessage: It is no longer necessary to explicitly enable strong mode.
comment: "An error code indicating that strong-mode: true is deprecated."
AnalysisOptionsWarningCode:
ANALYSIS_OPTION_DEPRECATED:
problemMessage: "The option '{0}' is no longer supported."
comment: |
An error code indicating that the given option is deprecated.
Parameters:
0: the option name
ANALYSIS_OPTION_DEPRECATED_WITH_REPLACEMENT:
sharedName: ANALYSIS_OPTION_DEPRECATED
problemMessage: "The option '{0}' is no longer supported."
correctionMessage: "Try using the new '{1}' option."
comment: |-
An error code indicating that the given option is deprecated.
Parameters:
0: the option name
1: the replacement option name
INCLUDED_FILE_WARNING:
problemMessage: "Warning in the included options file {0}({1}..{2}): {3}"
comment: |-
An error code indicating a specified include file has a warning.
Parameters:
0: the path of the file containing the warnings
1: the starting offset of the text in the file that contains the warning
2: the ending offset of the text in the file that contains the warning
3: the warning message
INCLUDE_FILE_NOT_FOUND:
problemMessage: "The include file '{0}' in '{1}' can't be found when analyzing '{2}'."
comment: |-
An error code indicating a specified include file could not be found.
Parameters:
0: the URI of the file to be included
1: the path of the file containing the include directive
2: the path of the context being analyzed
INVALID_OPTION:
problemMessage: "Invalid option specified for '{0}': {1}"
comment: |-
An error code indicating that a plugin is being configured with an invalid
value for an option and a detail message is provided.
Parameters:
0: the option name
1: the detail message
INVALID_SECTION_FORMAT:
problemMessage: "Invalid format for the '{0}' section."
comment: |-
An error code indicating an invalid format for an options file section.
Parameters:
0: the section name
MULTIPLE_PLUGINS:
problemMessage: "Multiple plugins can't be enabled."
correctionMessage: "Remove all plugins following the first, '{0}'."
comment: |-
An error code indicating multiple plugins have been specified as enabled.
Parameters:
0: the name of the first plugin
RECURSIVE_INCLUDE_FILE:
problemMessage: "The include file '{0}' in '{1}' includes itself recursively."
correctionMessage: "Try changing the chain of 'include's to not re-include this file."
comment: |-
An error code indicating a specified include file includes itself recursively.
Parameters:
0: the URI of the file to be included
1: the path of the file containing the include directive
REMOVED_LINT:
problemMessage: "'{0}' was removed in Dart '{1}'"
correctionMessage: "Remove the reference to '{0}'."
comment: |-
An error code indicating a removed lint rule.
Parameters:
0: the rule name
1: the SDK version in which the lint was removed
REPLACED_LINT:
problemMessage: "'{0}' was replaced by '{2}' in Dart '{1}'."
correctionMessage: "Replace '{0}' with '{1}'."
comment: |-
An error code indicating a removed lint rule.
Parameters:
0: the rule name
1: the SDK version in which the lint was removed
2: the name of a replacing lint
SPEC_MODE_REMOVED:
problemMessage: "The option 'strong-mode: false' is no longer supported."
correctionMessage: "It's recommended to remove the 'strong-mode:' setting (and make your code Dart 2 compliant)."
comment: "An error code indicating that strong-mode: false is has been removed."
UNRECOGNIZED_ERROR_CODE:
problemMessage: "'{0}' isn't a recognized error code."
comment: |-
An error code indicating that an unrecognized error code is being used to
specify an error filter.
Parameters:
0: the unrecognized error code
UNSUPPORTED_OPTION_WITHOUT_VALUES:
problemMessage: "The option '{1}' isn't supported by '{0}'."
comment: |-
An error code indicating that a plugin is being configured with an
unsupported option and legal options are provided.
Parameters:
0: the plugin name
1: the unsupported option key
UNSUPPORTED_OPTION_WITH_LEGAL_VALUE:
problemMessage: "The option '{1}' isn't supported by '{0}'. Try using the only supported option: '{2}'."
comment: |-
An error code indicating that a plugin is being configured with an
unsupported option where there is just one legal value.
Parameters:
0: the plugin name
1: the unsupported option key
2: the legal value
UNSUPPORTED_OPTION_WITH_LEGAL_VALUES:
problemMessage: "The option '{1}' isn't supported by '{0}'."
correctionMessage: "Try using one of the supported options: {2}."
comment: |-
An error code indicating that a plugin is being configured with an
unsupported option and legal options are provided.
Parameters:
0: the plugin name
1: the unsupported option key
2: legal values
UNSUPPORTED_VALUE:
problemMessage: "The value '{1}' isn't supported by '{0}'."
correctionMessage: "Try using one of the supported options: {2}."
comment: |-
An error code indicating that an option entry is being configured with an
unsupported value.
Parameters:
0: the option name
1: the unsupported value
2: legal values
CompileTimeErrorCode:
ABSTRACT_FIELD_CONSTRUCTOR_INITIALIZER:
sharedName: ABSTRACT_FIELD_INITIALIZER
problemMessage: "Abstract fields can't have initializers."
correctionMessage: "Try removing the field initializer or the 'abstract' keyword from the field declaration."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a field that has the `abstract`
modifier also has an initializer.
#### Examples
The following code produces this diagnostic because `f` is marked as
`abstract` and has an initializer:
```dart
abstract class C {
abstract int [!f!] = 0;
}
```
The following code produces this diagnostic because `f` is marked as
`abstract` and there's an initializer in the constructor:
```dart
abstract class C {
abstract int f;
C() : [!f!] = 0;
}
```
#### Common fixes
If the field must be abstract, then remove the initializer:
```dart
abstract class C {
abstract int f;
}
```
If the field isn't required to be abstract, then remove the keyword:
```dart
abstract class C {
int f = 0;
}
```
ABSTRACT_FIELD_INITIALIZER:
problemMessage: "Abstract fields can't have initializers."
correctionMessage: "Try removing the initializer or the 'abstract' keyword."
hasPublishedDocs: true
comment: No parameters.
ABSTRACT_SUPER_MEMBER_REFERENCE:
problemMessage: "The {0} '{1}' is always abstract in the supertype."
hasPublishedDocs: true
comment: |-
Parameters:
0: the display name for the kind of the found abstract member
1: the name of the member
documentation: |-
#### Description
The analyzer produces this diagnostic when an inherited member is
referenced using `super`, but there is no concrete implementation of the
member in the superclass chain. Abstract members can't be invoked.
#### Example
The following code produces this diagnostic because `B` doesn't inherit a
concrete implementation of `a`:
```dart
abstract class A {
int get a;
}
class B extends A {
int get a => super.[!a!];
}
```
#### Common fixes
Remove the invocation of the abstract member, possibly replacing it with an
invocation of a concrete member.
TODO(brianwilkerson) This either needs to be generalized (use 'member'
rather than '{0}') or split into multiple codes.
AMBIGUOUS_EXPORT:
problemMessage: "The name '{0}' is defined in the libraries '{1}' and '{2}'."
correctionMessage: Try removing the export of one of the libraries, or explicitly hiding the name in one of the export directives.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the ambiguous element
1: the name of the first library in which the type is found
2: the name of the second library in which the type is found
documentation: |-
#### Description
The analyzer produces this diagnostic when two or more export directives
cause the same name to be exported from multiple libraries.
#### Example
Given a file `a.dart` containing
```dart
%uri="lib/a.dart"
class C {}
```
And a file `b.dart` containing
```dart
%uri="lib/b.dart"
class C {}
```
The following code produces this diagnostic because the name `C` is being
exported from both `a.dart` and `b.dart`:
```dart
export 'a.dart';
export [!'b.dart'!];
```
#### Common fixes
If none of the names in one of the libraries needs to be exported, then
remove the unnecessary export directives:
```dart
export 'a.dart';
```
If all of the export directives are needed, then hide the name in all
except one of the directives:
```dart
export 'a.dart';
export 'b.dart' hide C;
```
AMBIGUOUS_EXTENSION_MEMBER_ACCESS:
problemMessage: "A member named '{0}' is defined in {1}, and none are more specific."
correctionMessage: Try using an extension override to specify the extension you want to be chosen.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the member
1: the names of the declaring extensions
documentation: |-
#### Description
When code refers to a member of an object (for example, `o.m()` or `o.m` or
`o[i]`) where the static type of `o` doesn't declare the member (`m` or
`[]`, for example), then the analyzer tries to find the member in an
extension. For example, if the member is `m`, then the analyzer looks for
extensions that declare a member named `m` and have an extended type that
the static type of `o` can be assigned to. When there's more than one such
extension in scope, the extension whose extended type is most specific is
selected.
The analyzer produces this diagnostic when none of the extensions has an
extended type that's more specific than the extended types of all of the
other extensions, making the reference to the member ambiguous.
#### Example
The following code produces this diagnostic because there's no way to
choose between the member in `E1` and the member in `E2`:
```dart
extension E1 on String {
int get charCount => 1;
}
extension E2 on String {
int get charCount => 2;
}
void f(String s) {
print(s.[!charCount!]);
}
```
#### Common fixes
If you don't need both extensions, then you can delete or hide one of them.
If you need both, then explicitly select the one you want to use by using
an extension override:
```dart
extension E1 on String {
int get charCount => length;
}
extension E2 on String {
int get charCount => length;
}
void f(String s) {
print(E2(s).charCount);
}
```
AMBIGUOUS_IMPORT:
problemMessage: "The name '{0}' is defined in the libraries {1}."
correctionMessage: "Try using 'as prefix' for one of the import directives, or hiding the name from all but one of the imports."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the ambiguous type
1: the names of the libraries that the type is found
documentation: |-
#### Description
The analyzer produces this diagnostic when a name is referenced that is
declared in two or more imported libraries.
#### Example
Given a library (`a.dart`) that defines a class (`C` in this example):
```dart
%uri="lib/a.dart"
class A {}
class C {}
```
And a library (`b.dart`) that defines a different class with the same name:
```dart
%uri="lib/b.dart"
class B {}
class C {}
```
The following code produces this diagnostic:
```dart
import 'a.dart';
import 'b.dart';
void f([!C!] c1, [!C!] c2) {}
```
#### Common fixes
If any of the libraries aren't needed, then remove the import directives
for them:
```dart
import 'a.dart';
void f(C c1, C c2) {}
```
If the name is still defined by more than one library, then add a `hide`
clause to the import directives for all except one library:
```dart
import 'a.dart' hide C;
import 'b.dart';
void f(C c1, C c2) {}
```
If you must be able to reference more than one of these types, then add a
prefix to each of the import directives, and qualify the references with
the appropriate prefix:
```dart
import 'a.dart' as a;
import 'b.dart' as b;
void f(a.C c1, b.C c2) {}
```
AMBIGUOUS_SET_OR_MAP_LITERAL_BOTH:
problemMessage: "The literal can't be either a map or a set because it contains at least one literal map entry or a spread operator spreading a 'Map', and at least one element which is neither of these."
correctionMessage: Try removing or changing some of the elements so that all of the elements are consistent.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
Because map and set literals use the same delimiters (`{` and `}`), the
analyzer looks at the type arguments and the elements to determine which
kind of literal you meant. When there are no type arguments, then the
analyzer uses the types of the elements. If all of the elements are literal
map entries and all of the spread operators are spreading a `Map` then it's
a `Map`. If none of the elements are literal map entries and all of the
spread operators are spreading an `Iterable`, then it's a `Set`. If neither
of those is true then it's ambiguous.
The analyzer produces this diagnostic when at least one element is a
literal map entry or a spread operator spreading a `Map`, and at least one
element is neither of these, making it impossible for the analyzer to
determine whether you are writing a map literal or a set literal.
#### Example
The following code produces this diagnostic:
```dart
union(Map<String, String> a, List<String> b, Map<String, String> c) =>
[!{...a, ...b, ...c}!];
```
The list `b` can only be spread into a set, and the maps `a` and `c` can
only be spread into a map, and the literal can't be both.
#### Common fixes
There are two common ways to fix this problem. The first is to remove all
of the spread elements of one kind or another, so that the elements are
consistent. In this case, that likely means removing the list and deciding
what to do about the now unused parameter:
```dart
union(Map<String, String> a, List<String> b, Map<String, String> c) =>
{...a, ...c};
```
The second fix is to change the elements of one kind into elements that are
consistent with the other elements. For example, you can add the elements
of the list as keys that map to themselves:
```dart
union(Map<String, String> a, List<String> b, Map<String, String> c) =>
{...a, for (String s in b) s: s, ...c};
```
AMBIGUOUS_SET_OR_MAP_LITERAL_EITHER:
problemMessage: "This literal must be either a map or a set, but the elements don't have enough information for type inference to work."
correctionMessage: Try adding type arguments to the literal (one for sets, two for maps).
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
Because map and set literals use the same delimiters (`{` and `}`), the
analyzer looks at the type arguments and the elements to determine which
kind of literal you meant. When there are no type arguments and all of the
elements are spread elements (which are allowed in both kinds of literals)
then the analyzer uses the types of the expressions that are being spread.
If all of the expressions have the type `Iterable`, then it's a set
literal; if they all have the type `Map`, then it's a map literal.
This diagnostic is produced when none of the expressions being spread have
a type that allows the analyzer to decide whether you were writing a map
literal or a set literal.
#### Example
The following code produces this diagnostic:
```dart
union(a, b) => [!{...a, ...b}!];
```
The problem occurs because there are no type arguments, and there is no
information about the type of either `a` or `b`.
#### Common fixes
There are three common ways to fix this problem. The first is to add type
arguments to the literal. For example, if the literal is intended to be a
map literal, you might write something like this:
```dart
union(a, b) => <String, String>{...a, ...b};
```
The second fix is to add type information so that the expressions have
either the type `Iterable` or the type `Map`. You can add an explicit cast
or, in this case, add types to the declarations of the two parameters:
```dart
union(List<int> a, List<int> b) => {...a, ...b};
```
The third fix is to add context information. In this case, that means
adding a return type to the function:
```dart
Set<String> union(a, b) => {...a, ...b};
```
In other cases, you might add a type somewhere else. For example, say the
original code looks like this:
```dart
union(a, b) {
var x = [!{...a, ...b}!];
return x;
}
```
You might add a type annotation on `x`, like this:
```dart
union(a, b) {
Map<String, String> x = {...a, ...b};
return x;
}
```
ARGUMENT_TYPE_NOT_ASSIGNABLE:
problemMessage: "The argument type '{0}' can't be assigned to the parameter type '{1}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the actual argument type
1: the name of the expected type
documentation: |-
#### Description
The analyzer produces this diagnostic when the static type of an argument
can't be assigned to the static type of the corresponding parameter.
#### Example
The following code produces this diagnostic because a `num` can't be
assigned to a `String`:
```dart
%language=2.9
String f(String x) => x;
String g(num y) => f([!y!]);
```
#### Common fixes
If possible, rewrite the code so that the static type is assignable. In the
example above you might be able to change the type of the parameter `y`:
```dart
%language=2.9
String f(String x) => x;
String g(String y) => f(y);
```
If that fix isn't possible, then add code to handle the case where the
argument value isn't the required type. One approach is to coerce other
types to the required type:
```dart
%language=2.9
String f(String x) => x;
String g(num y) => f(y.toString());
```
Another approach is to add explicit type tests and fallback code:
```dart
%language=2.9
String f(String x) => x;
String g(num y) => f(y is String ? y : '');
```
If you believe that the runtime type of the argument will always be the
same as the static type of the parameter, and you're willing to risk having
an exception thrown at runtime if you're wrong, then add an explicit cast:
```dart
String f(String x) => x;
String g(num y) => f(y as String);
```
ASSERT_IN_REDIRECTING_CONSTRUCTOR:
problemMessage: "A redirecting constructor can't have an 'assert' initializer."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a redirecting constructor (a
constructor that redirects to another constructor in the same class) has an
assert in the initializer list.
#### Example
The following code produces this diagnostic because the unnamed constructor
is a redirecting constructor and also has an assert in the initializer
list:
```dart
class C {
C(int x) : [!assert(x > 0)!], this.name();
C.name() {}
}
```
#### Common fixes
If the assert isn't needed, then remove it:
```dart
class C {
C(int x) : this.name();
C.name() {}
}
```
If the assert is needed, then convert the constructor into a factory
constructor:
```dart
class C {
factory C(int x) {
assert(x > 0);
return C.name();
}
C.name() {}
}
```
ASSIGNMENT_TO_CONST:
problemMessage: "Constant variables can't be assigned a value."
correctionMessage: "Try removing the assignment, or remove the modifier 'const' from the variable."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when it finds an assignment to a
top-level variable, a static field, or a local variable that has the
`const` modifier. The value of a compile-time constant can't be changed at
runtime.
#### Example
The following code produces this diagnostic because `c` is being assigned a
value even though it has the `const` modifier:
```dart
const c = 0;
void f() {
[!c!] = 1;
print(c);
}
```
#### Common fixes
If the variable must be assignable, then remove the `const` modifier:
```dart
var c = 0;
void f() {
c = 1;
print(c);
}
```
If the constant shouldn't be changed, then either remove the assignment or
use a local variable in place of references to the constant:
```dart
const c = 0;
void f() {
var v = 1;
print(v);
}
```
ASSIGNMENT_TO_FINAL:
problemMessage: "'{0}' can't be used as a setter because it's final."
correctionMessage: "Try finding a different setter, or making '{0}' non-final."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the final variable
documentation: |-
#### Description
The analyzer produces this diagnostic when it finds an invocation of a
setter, but there's no setter because the field with the same name was
declared to be `final` or `const`.
#### Example
The following code produces this diagnostic because `v` is final:
```dart
class C {
final v = 0;
}
f(C c) {
c.[!v!] = 1;
}
```
#### Common fixes
If you need to be able to set the value of the field, then remove the
modifier `final` from the field:
```dart
class C {
int v = 0;
}
f(C c) {
c.v = 1;
}
```
ASSIGNMENT_TO_FINAL_LOCAL:
problemMessage: "The final variable '{0}' can only be set once."
correctionMessage: "Try making '{0}' non-final."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the variable
documentation: |-
#### Description
The analyzer produces this diagnostic when a local variable that was
declared to be final is assigned after it was initialized.
#### Example
The following code produces this diagnostic because `x` is final, so it
can't have a value assigned to it after it was initialized:
```dart
void f() {
final x = 0;
[!x!] = 3;
print(x);
}
```
#### Common fixes
Remove the keyword `final`, and replace it with `var` if there's no type
annotation:
```dart
void f() {
var x = 0;
x = 3;
print(x);
}
```
ASSIGNMENT_TO_FINAL_NO_SETTER:
problemMessage: "There isn't a setter named '{0}' in class '{1}'."
correctionMessage: Try correcting the name to reference an existing setter, or declare the setter.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the reference
1: the name of the class
documentation: |-
#### Description
The analyzer produces this diagnostic when a reference to a setter is
found; there is no setter defined for the type; but there is a getter
defined with the same name.
#### Example
The following code produces this diagnostic because there is no setter
named `x` in `C`, but there is a getter named `x`:
```dart
class C {
int get x => 0;
set y(int p) {}
}
void f(C c) {
c.[!x!] = 1;
}
```
#### Common fixes
If you want to invoke an existing setter, then correct the name:
```dart
class C {
int get x => 0;
set y(int p) {}
}
void f(C c) {
c.y = 1;
}
```
If you want to invoke the setter but it just doesn't exist yet, then
declare it:
```dart
class C {
int get x => 0;
set x(int p) {}
set y(int p) {}
}
void f(C c) {
c.x = 1;
}
```
ASSIGNMENT_TO_FUNCTION:
problemMessage: "Functions can't be assigned a value."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the name of a function appears
on the left-hand side of an assignment expression.
#### Example
The following code produces this diagnostic because the assignment to the
function `f` is invalid:
```dart
void f() {}
void g() {
[!f!] = () {};
}
```
#### Common fixes
If the right-hand side should be assigned to something else, such as a
local variable, then change the left-hand side:
```dart
void f() {}
void g() {
var x = () {};
print(x);
}
```
If the intent is to change the implementation of the function, then define
a function-valued variable instead of a function:
```dart
void Function() f = () {};
void g() {
f = () {};
}
```
ASSIGNMENT_TO_METHOD:
problemMessage: "Methods can't be assigned a value."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the target of an assignment is a
method.
#### Example
The following code produces this diagnostic because `f` can't be assigned a
value because it's a method:
```dart
class C {
void f() {}
void g() {
[!f!] = null;
}
}
```
#### Common fixes
Rewrite the code so that there isn't an assignment to a method.
ASSIGNMENT_TO_TYPE:
problemMessage: "Types can't be assigned a value."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the name of a type name appears
on the left-hand side of an assignment expression.
#### Example
The following code produces this diagnostic because the assignment to the
class `C` is invalid:
```dart
class C {}
void f() {
[!C!] = null;
}
```
#### Common fixes
If the right-hand side should be assigned to something else, such as a
local variable, then change the left-hand side:
```dart
void f() {}
void g() {
var c = null;
print(c);
}
```
ASYNC_FOR_IN_WRONG_CONTEXT:
problemMessage: The async for-in loop can only be used in an async function.
correctionMessage: Try marking the function body with either 'async' or 'async*', or removing the 'await' before the for-in loop.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when an async for-in loop is found in
a function or method whose body isn't marked as being either `async` or
`async*`.
#### Example
The following code produces this diagnostic because the body of `f` isn't
marked as being either `async` or `async*`, but `f` contains an async
for-in loop:
```dart
void f(list) {
[!await!] for (var e in list) {
print(e);
}
}
```
#### Common fixes
If the function should return a `Future`, then mark the body with `async`:
```dart
Future<void> f(list) async {
await for (var e in list) {
print(e);
}
}
```
If the function should return a `Stream` of values, then mark the body with
`async*`:
```dart
Stream<void> f(list) async* {
await for (var e in list) {
print(e);
}
}
```
If the function should be synchronous, then remove the `await` before the
loop:
```dart
void f(list) {
for (var e in list) {
print(e);
}
}
```
AWAIT_IN_LATE_LOCAL_VARIABLE_INITIALIZER:
problemMessage: "The 'await' expression can't be used in a 'late' local variable's initializer."
correctionMessage: "Try removing the 'late' modifier, or rewriting the initializer without using the 'await' expression."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a local variable that has the
`late` modifier uses an `await` expression in the initializer.
#### Example
The following code produces this diagnostic because an `await` expression
is used in the initializer for `v`, a local variable that is marked `late`:
```dart
Future<int> f() async {
late var v = [!await!] 42;
return v;
}
```
#### Common fixes
If the initializer can be rewritten to not use `await`, then rewrite it:
```dart
Future<int> f() async {
late var v = 42;
return v;
}
```
If the initializer can't be rewritten, then remove the `late` modifier:
```dart
Future<int> f() async {
var v = await 42;
return v;
}
```
AWAIT_IN_WRONG_CONTEXT:
problemMessage: The await expression can only be used in an async function.
correctionMessage: Try marking the function body with either 'async' or 'async*'.
comment: |-
16.30 Await Expressions: It is a compile-time error if the function
immediately enclosing _a_ is not declared asynchronous. (Where _a_ is the
await expression.)
AWAIT_OF_EXTENSION_TYPE_NOT_FUTURE:
problemMessage: "The 'await' expression can't be used for an expression with an extension type that is not a subtype of 'Future'."
correctionMessage: Try updating the extension type to implement 'Future'.
BASE_CLASS_IMPLEMENTED_OUTSIDE_OF_LIBRARY:
sharedName: INVALID_USE_OF_TYPE_OUTSIDE_LIBRARY
problemMessage: "The class '{0}' can't be implemented outside of its library because it's a base class."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the base class being implemented
documentation: |-
#### Description
The analyzer produces this diagnostic when an `extends`, `implements`,
`with`, or `on` clause uses a class or mixin in a way that isn't allowed
given the modifiers on that class or mixin's declaration.
The message specifies how the declaration is being used and why it isn't
allowed.
#### Example
Given a file `a.dart` that defines a base class `A`:
```dart
%uri="lib/a.dart"
base class A {}
```
The following code produces this diagnostic because the class `B`
implements the class `A`, but the `base` modifier prevents `A` from being
implemented outside of the library where it's defined:
```dart
import 'a.dart';
final class B implements [!A!] {}
```
#### Common fixes
Use of this type is restricted outside of its declaring library. If a
different, unrestricted type is available that can provide similar
functionality, then replace the type:
```dart
class B implements C {}
class C {}
```
If there isn't a different type that would be appropriate, then remove the
type, and possibly the whole clause:
```dart
class B {}
```
BASE_MIXIN_IMPLEMENTED_OUTSIDE_OF_LIBRARY:
sharedName: INVALID_USE_OF_TYPE_OUTSIDE_LIBRARY
problemMessage: "The mixin '{0}' can't be implemented outside of its library because it's a base mixin."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the base mixin being implemented
BODY_MIGHT_COMPLETE_NORMALLY:
problemMessage: The body might complete normally, causing 'null' to be returned, but the return type, '{0}', is a potentially non-nullable type.
correctionMessage: Try adding either a return or a throw statement at the end.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the return type
documentation: |-
#### Description
The analyzer produces this diagnostic when a method or function has a
return type that's [potentially non-nullable][] but would implicitly return
`null` if control reached the end of the function.
#### Examples
The following code produces this diagnostic because the method `m` has an
implicit return of `null` inserted at the end of the method, but the method
is declared to not return `null`:
```dart
class C {
int [!m!](int t) {
print(t);
}
}
```
The following code produces this diagnostic because the method `m` has an
implicit return of `null` inserted at the end of the method, but because
the class `C` can be instantiated with a non-nullable type argument, the
method is effectively declared to not return `null`:
```dart
class C<T> {
T [!m!](T t) {
print(t);
}
}
```
#### Common fixes
If there's a reasonable value that can be returned, then add a `return`
statement at the end of the method:
```dart
class C<T> {
T m(T t) {
print(t);
return t;
}
}
```
If the method won't reach the implicit return, then add a `throw` at the
end of the method:
```dart
class C<T> {
T m(T t) {
print(t);
throw '';
}
}
```
If the method intentionally returns `null` at the end, then add an
explicit return of `null` at the end of the method and change the
return type so that it's valid to return `null`:
```dart
class C<T> {
T? m(T t) {
print(t);
return null;
}
}
```
BREAK_LABEL_ON_SWITCH_MEMBER:
problemMessage: A break label resolves to the 'case' or 'default' statement.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a break in a case clause inside
a switch statement has a label that is associated with another case clause.
#### Example
The following code produces this diagnostic because the label `l` is
associated with the case clause for `0`:
```dart
%language=2.18
void f(int i) {
switch (i) {
l: case 0:
break;
case 1:
break [!l!];
}
}
```
#### Common fixes
If the intent is to transfer control to the statement after the switch,
then remove the label from the break statement:
```dart
void f(int i) {
switch (i) {
case 0:
break;
case 1:
break;
}
}
```
If the intent is to transfer control to a different case block, then use
`continue` rather than `break`:
```dart
%language=2.18
void f(int i) {
switch (i) {
l: case 0:
break;
case 1:
continue l;
}
}
```
BUILT_IN_IDENTIFIER_AS_TYPE:
problemMessage: The built-in identifier '{0}' can't be used as a type.
correctionMessage: Try correcting the name to match an existing type.
hasPublishedDocs: true
comment: |-
Parameters:
0: the built-in identifier that is being used
documentation: |-
#### Description
The analyzer produces this diagnostic when a built-in identifier is used
where a type name is expected.
#### Example
The following code produces this diagnostic because `import` can't be used
as a type because it's a built-in identifier:
```dart
[!import!]<int> x;
```
#### Common fixes
Replace the built-in identifier with the name of a valid type:
```dart
List<int> x;
```
BUILT_IN_IDENTIFIER_AS_EXTENSION_NAME:
sharedName: BUILT_IN_IDENTIFIER_IN_DECLARATION
problemMessage: "The built-in identifier '{0}' can't be used as an extension name."
correctionMessage: Try choosing a different name for the extension.
hasPublishedDocs: true
comment: |-
Parameters:
0: the built-in identifier that is being used
documentation: |-
#### Description
The analyzer produces this diagnostic when the name used in the declaration
of a class, extension, mixin, typedef, type parameter, or import prefix is
a built-in identifier. Built-in identifiers can't be used to name any of
these kinds of declarations.
#### Example
The following code produces this diagnostic because `mixin` is a built-in
identifier:
```dart
extension [!mixin!] on int {}
```
#### Common fixes
Choose a different name for the declaration.
BUILT_IN_IDENTIFIER_AS_PREFIX_NAME:
sharedName: BUILT_IN_IDENTIFIER_IN_DECLARATION
problemMessage: "The built-in identifier '{0}' can't be used as a prefix name."
correctionMessage: Try choosing a different name for the prefix.
hasPublishedDocs: true
comment: |-
Parameters:
0: the built-in identifier that is being used
BUILT_IN_IDENTIFIER_AS_TYPE_NAME:
sharedName: BUILT_IN_IDENTIFIER_IN_DECLARATION
problemMessage: "The built-in identifier '{0}' can't be used as a type name."
correctionMessage: Try choosing a different name for the type.
hasPublishedDocs: true
comment: |-
Parameters:
0: the built-in identifier that is being used
BUILT_IN_IDENTIFIER_AS_TYPE_PARAMETER_NAME:
sharedName: BUILT_IN_IDENTIFIER_IN_DECLARATION
problemMessage: "The built-in identifier '{0}' can't be used as a type parameter name."
correctionMessage: Try choosing a different name for the type parameter.
hasPublishedDocs: true
comment: |-
Parameters:
0: the built-in identifier that is being used
BUILT_IN_IDENTIFIER_AS_TYPEDEF_NAME:
sharedName: BUILT_IN_IDENTIFIER_IN_DECLARATION
problemMessage: "The built-in identifier '{0}' can't be used as a typedef name."
correctionMessage: Try choosing a different name for the typedef.
hasPublishedDocs: true
comment: |-
Parameters:
0: the built-in identifier that is being used
CASE_BLOCK_NOT_TERMINATED:
problemMessage: "The last statement of the 'case' should be 'break', 'continue', 'rethrow', 'return', or 'throw'."
correctionMessage: Try adding one of the required statements.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the last statement in a `case`
block isn't one of the required terminators: `break`, `continue`,
`rethrow`, `return`, or `throw`.
#### Example
The following code produces this diagnostic because the `case` block ends
with an assignment:
```dart
%language=2.9
void f(int x) {
switch (x) {
[!case!] 0:
x += 2;
default:
x += 1;
}
}
```
#### Common fixes
Add one of the required terminators:
```dart
%language=2.9
void f(int x) {
switch (x) {
case 0:
x += 2;
break;
default:
x += 1;
}
}
```
CASE_EXPRESSION_TYPE_IMPLEMENTS_EQUALS:
problemMessage: "The switch case expression type '{0}' can't override the '==' operator."
hasPublishedDocs: true
comment: |-
Parameters:
0: the this of the switch case expression
documentation: |-
#### Description
The analyzer produces this diagnostic when the type of the expression
following the keyword `case` has an implementation of the `==` operator
other than the one in `Object`.
#### Example
The following code produces this diagnostic because the expression
following the keyword `case` (`C(0)`) has the type `C`, and the class `C`
overrides the `==` operator:
```dart
%language=2.18
class C {
final int value;
const C(this.value);
bool operator ==(Object other) {
return false;
}
}
void f(C c) {
switch (c) {
case [!C(0)!]:
break;
}
}
```
#### Common fixes
If there isn't a strong reason not to do so, then rewrite the code to use
an if-else structure:
```dart
class C {
final int value;
const C(this.value);
bool operator ==(Object other) {
return false;
}
}
void f(C c) {
if (c == C(0)) {
// ...
}
}
```
If you can't rewrite the switch statement and the implementation of `==`
isn't necessary, then remove it:
```dart
%language=2.18
class C {
final int value;
const C(this.value);
}
void f(C c) {
switch (c) {
case C(0):
break;
}
}
```
If you can't rewrite the switch statement and you can't remove the
definition of `==`, then find some other value that can be used to control
the switch:
```dart
class C {
final int value;
const C(this.value);
bool operator ==(Object other) {
return false;
}
}
void f(C c) {
switch (c.value) {
case 0:
break;
}
}
```
CASE_EXPRESSION_TYPE_IS_NOT_SWITCH_EXPRESSION_SUBTYPE:
problemMessage: "The switch case expression type '{0}' must be a subtype of the switch expression type '{1}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the type of the case expression
1: the type of the switch expression
documentation: |-
#### Description
The analyzer produces this diagnostic when the expression following `case`
in a `switch` statement has a static type that isn't a subtype of the
static type of the expression following `switch`.
#### Example
The following code produces this diagnostic because `1` is an `int`, which
isn't a subtype of `String` (the type of `s`):
```dart
%language=2.18
void f(String s) {
switch (s) {
case [!1!]:
break;
}
}
```
#### Common fixes
If the value of the `case` expression is wrong, then change the `case`
expression so that it has the required type:
```dart
void f(String s) {
switch (s) {
case '1':
break;
}
}
```
If the value of the `case` expression is correct, then change the `switch`
expression to have the required type:
```dart
void f(int s) {
switch (s) {
case 1:
break;
}
}
```
CAST_TO_NON_TYPE:
problemMessage: "The name '{0}' isn't a type, so it can't be used in an 'as' expression."
correctionMessage: "Try changing the name to the name of an existing type, or creating a type with the name '{0}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the type
documentation: |-
#### Description
The analyzer produces this diagnostic when the name following the `as` in a
cast expression is defined to be something other than a type.
#### Example
The following code produces this diagnostic because `x` is a variable, not
a type:
```dart
num x = 0;
int y = x as [!x!];
```
#### Common fixes
Replace the name with the name of a type:
```dart
num x = 0;
int y = x as int;
```
CLASS_USED_AS_MIXIN:
problemMessage: "The class '{0}' can't be used as a mixin because it's neither a mixin class nor a mixin."
comment: |-
Parameters:
0: the name of the class being used as a mixin
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a class that is neither a
`mixin class` nor a `mixin` is used in a `with` clause.
#### Example
The following code produces this diagnostic because the class `M` is being
used as a mixin, but it isn't defined as a `mixin class`:
```dart
class M {}
class C with [!M!] {}
```
#### Common fixes
If the class can be a pure mixin, then change `class` to `mixin`:
```dart
mixin M {}
class C with M {}
```
If the class needs to be both a class and a mixin, then add `mixin`:
```dart
mixin class M {}
class C with M {}
```
CLASS_INSTANTIATION_ACCESS_TO_INSTANCE_MEMBER:
sharedName: CLASS_INSTANTIATION_ACCESS_TO_MEMBER
problemMessage: "The instance member '{0}' can't be accessed on a class instantiation."
correctionMessage: Try changing the member name to the name of a constructor.
comment: |-
Parameters:
0: the name of the member
CLASS_INSTANTIATION_ACCESS_TO_UNKNOWN_MEMBER:
sharedName: CLASS_INSTANTIATION_ACCESS_TO_MEMBER
problemMessage: "The class '{0}' doesn't have a constructor named '{1}'."
correctionMessage: "Try invoking a different constructor, or defining a constructor named '{1}'."
comment: |-
Parameters:
0: the name of the class
1: the name of the member
CLASS_INSTANTIATION_ACCESS_TO_STATIC_MEMBER:
sharedName: CLASS_INSTANTIATION_ACCESS_TO_MEMBER
problemMessage: "The static member '{0}' can't be accessed on a class instantiation."
correctionMessage: Try removing the type arguments from the class name, or changing the member name to the name of a constructor.
comment: |-
Parameters:
0: the name of the member
NON_CONST_GENERATIVE_ENUM_CONSTRUCTOR:
problemMessage: Generative enum constructors must be 'const'.
correctionMessage: Try adding the keyword 'const'.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when an enum declaration contains a
generative constructor that isn't marked as `const`.
#### Example
The following code produces this diagnostic because the constructor in `E`
isn't marked as being `const`:
```dart
enum E {
e;
[!E!]();
}
```
#### Common fixes
Add the `const` keyword before the constructor:
```dart
enum E {
e;
const E();
}
```
NON_CONSTANT_MAP_KEY_FROM_DEFERRED_LIBRARY:
sharedName: COLLECTION_ELEMENT_FROM_DEFERRED_LIBRARY
problemMessage: "Constant values from a deferred library can't be used as keys in a 'const' map literal."
correctionMessage: "Try removing the keyword 'const' from the map literal or removing the keyword 'deferred' from the import."
hasPublishedDocs: true
comment: No parameters.
NON_CONSTANT_LIST_ELEMENT_FROM_DEFERRED_LIBRARY:
sharedName: COLLECTION_ELEMENT_FROM_DEFERRED_LIBRARY
problemMessage: "Constant values from a deferred library can't be used as values in a 'const' list literal."
correctionMessage: "Try removing the keyword 'const' from the list literal or removing the keyword 'deferred' from the import."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a collection literal that is
either explicitly (because it's prefixed by the `const` keyword) or
implicitly (because it appears in a [constant context][]) a constant
contains a value that is declared in a library that is imported using a
deferred import. Constants are evaluated at compile time, and values from
deferred libraries aren't available at compile time.
For more information, check out
[Lazily loading a library](https://dart.dev/language/libraries#lazily-loading-a-library).
#### Example
Given a file `a.dart` that defines the constant `zero`:
```dart
%uri="lib/a.dart"
const zero = 0;
```
The following code produces this diagnostic because the constant list
literal contains `a.zero`, which is imported using a `deferred` import:
```dart
import 'a.dart' deferred as a;
var l = const [a.[!zero!]];
```
#### Common fixes
If the collection literal isn't required to be constant, then remove the
`const` keyword:
```dart
import 'a.dart' deferred as a;
var l = [a.zero];
```
If the collection is required to be constant and the imported constant must
be referenced, then remove the keyword `deferred` from the import:
```dart
import 'a.dart' as a;
var l = const [a.zero];
```
If you don't need to reference the constant, then replace it with a
suitable value:
```dart
var l = const [0];
```
PATTERN_CONSTANT_FROM_DEFERRED_LIBRARY:
problemMessage: Constant values from a deferred library can't be used in patterns.
correctionMessage: Try removing the keyword 'deferred' from the import.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a pattern contains a value
declared in a different library, and that library is imported using a
deferred import. Constants are evaluated at compile time, but values from
deferred libraries aren't available at compile time.
For more information, check out
[Lazily loading a library](https://dart.dev/language/libraries#lazily-loading-a-library).
#### Example
Given a file `a.dart` that defines the constant `zero`:
```dart
%uri="lib/a.dart"
const zero = 0;
```
The following code produces this diagnostic because the constant pattern
`a.zero` is imported using a deferred import:
```dart
import 'a.dart' deferred as a;
void f(int x) {
switch (x) {
case a.[!zero!]:
// ...
break;
}
}
```
#### Common fixes
If you need to reference the constant from the imported library, then
remove the `deferred` keyword:
```dart
import 'a.dart' as a;
void f(int x) {
switch (x) {
case a.zero:
// ...
break;
}
}
```
If you need to reference the constant from the imported library and also
need the imported library to be deferred, then rewrite the switch
statement as a sequence of `if` statements:
```dart
import 'a.dart' deferred as a;
void f(int x) {
if (x == a.zero) {
// ...
}
}
```
If you don't need to reference the constant, then replace the case
expression:
```dart
void f(int x) {
switch (x) {
case 0:
// ...
break;
}
}
```
SET_ELEMENT_FROM_DEFERRED_LIBRARY:
sharedName: COLLECTION_ELEMENT_FROM_DEFERRED_LIBRARY
problemMessage: "Constant values from a deferred library can't be used as values in a 'const' set literal."
correctionMessage: "Try removing the keyword 'const' from the set literal or removing the keyword 'deferred' from the import."
hasPublishedDocs: true
comment: No parameters.
NON_CONSTANT_MAP_VALUE_FROM_DEFERRED_LIBRARY:
sharedName: COLLECTION_ELEMENT_FROM_DEFERRED_LIBRARY
problemMessage: "Constant values from a deferred library can't be used as values in a 'const' map literal."
correctionMessage: "Try removing the keyword 'const' from the map literal or removing the keyword 'deferred' from the import."
hasPublishedDocs: true
comment: No parameters.
CONCRETE_CLASS_HAS_ENUM_SUPERINTERFACE:
problemMessage: "Concrete classes can't have 'Enum' as a superinterface."
correctionMessage: Try specifying a different interface, or remove it from the list.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a concrete class indirectly has
the class `Enum` as a superinterface.
#### Example
The following code produces this diagnostic because the concrete class `B`
has `Enum` as a superinterface as a result of implementing `A`:
```dart
abstract class A implements Enum {}
class [!B!] implements A {}
```
#### Common fixes
If the implemented class isn't the class you intend to implement, then
change it:
```dart
abstract class A implements Enum {}
class B implements C {}
class C {}
```
If the implemented class can be changed to not implement `Enum`, then do
so:
```dart
abstract class A {}
class B implements A {}
```
If the implemented class can't be changed to not implement `Enum`, then
remove it from the `implements` clause:
```dart
abstract class A implements Enum {}
class B {}
```
CONCRETE_CLASS_WITH_ABSTRACT_MEMBER:
problemMessage: "'{0}' must have a method body because '{1}' isn't abstract."
correctionMessage: "Try making '{1}' abstract, or adding a body to '{0}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the abstract method
1: the name of the enclosing class
documentation: |-
#### Description
The analyzer produces this diagnostic when a member of a concrete class is
found that doesn't have a concrete implementation. Concrete classes aren't
allowed to contain abstract members.
#### Example
The following code produces this diagnostic because `m` is an abstract
method but `C` isn't an abstract class:
```dart
class C {
[!void m();!]
}
```
#### Common fixes
If it's valid to create instances of the class, provide an implementation
for the member:
```dart
class C {
void m() {}
}
```
If it isn't valid to create instances of the class, mark the class as being
abstract:
```dart
abstract class C {
void m();
}
```
CONFLICTING_CONSTRUCTOR_AND_STATIC_FIELD:
sharedName: CONFLICTING_CONSTRUCTOR_AND_STATIC_MEMBER
problemMessage: "'{0}' can't be used to name both a constructor and a static field in this class."
correctionMessage: Try renaming either the constructor or the field.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the constructor and field
documentation: |-
#### Description
The analyzer produces this diagnostic when a named constructor and either a
static method or static field have the same name. Both are accessed using
the name of the class, so having the same name makes the reference
ambiguous.
#### Examples
The following code produces this diagnostic because the static field `foo`
and the named constructor `foo` have the same name:
```dart
class C {
C.[!foo!]();
static int foo = 0;
}
```
The following code produces this diagnostic because the static method `foo`
and the named constructor `foo` have the same name:
```dart
class C {
C.[!foo!]();
static void foo() {}
}
```
#### Common fixes
Rename either the member or the constructor.
CONFLICTING_CONSTRUCTOR_AND_STATIC_GETTER:
sharedName: CONFLICTING_CONSTRUCTOR_AND_STATIC_MEMBER
problemMessage: "'{0}' can't be used to name both a constructor and a static getter in this class."
correctionMessage: Try renaming either the constructor or the getter.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the constructor and getter
CONFLICTING_CONSTRUCTOR_AND_STATIC_METHOD:
sharedName: CONFLICTING_CONSTRUCTOR_AND_STATIC_MEMBER
problemMessage: "'{0}' can't be used to name both a constructor and a static method in this class."
correctionMessage: Try renaming either the constructor or the method.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the constructor
CONFLICTING_CONSTRUCTOR_AND_STATIC_SETTER:
sharedName: CONFLICTING_CONSTRUCTOR_AND_STATIC_MEMBER
problemMessage: "'{0}' can't be used to name both a constructor and a static setter in this class."
correctionMessage: Try renaming either the constructor or the setter.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the constructor and setter
CONFLICTING_FIELD_AND_METHOD:
problemMessage: "Class '{0}' can't define field '{1}' and have method '{2}.{1}' with the same name."
correctionMessage: "Try converting the getter to a method, or renaming the field to a name that doesn't conflict."
comment: |-
10.11 Class Member Conflicts: Let `C` be a class. It is a compile-time
error if `C` declares a getter or a setter with basename `n`, and has a
method named `n`.
Parameters:
0: the name of the class defining the conflicting field
1: the name of the conflicting field
2: the name of the class defining the method with which the field conflicts
CONFLICTING_GENERIC_INTERFACES:
problemMessage: "The class '{0}' can't implement both '{1}' and '{2}' because the type arguments are different."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the class implementing the conflicting interface
1: the first conflicting type
2: the second conflicting type
documentation: |-
#### Description
The analyzer produces this diagnostic when a class attempts to implement a
generic interface multiple times, and the values of the type arguments
aren't the same.
#### Example
The following code produces this diagnostic because `C` is defined to
implement both `I<int>` (because it extends `A`) and `I<String>` (because
it implements`B`), but `int` and `String` aren't the same type:
```dart
class I<T> {}
class A implements I<int> {}
class B implements I<String> {}
class [!C!] extends A implements B {}
```
#### Common fixes
Rework the type hierarchy to avoid this situation. For example, you might
make one or both of the inherited types generic so that `C` can specify the
same type for both type arguments:
```dart
class I<T> {}
class A<S> implements I<S> {}
class B implements I<String> {}
class C extends A<String> implements B {}
```
CONFLICTING_METHOD_AND_FIELD:
problemMessage: "Class '{0}' can't define method '{1}' and have field '{2}.{1}' with the same name."
correctionMessage: "Try converting the method to a getter, or renaming the method to a name that doesn't conflict."
comment: |-
10.11 Class Member Conflicts: Let `C` be a class. It is a compile-time
error if `C` declares a method named `n`, and has a getter or a setter
with basename `n`.
Parameters:
0: the name of the class defining the conflicting method
1: the name of the conflicting method
2: the name of the class defining the field with which the method conflicts
CONFLICTING_STATIC_AND_INSTANCE:
problemMessage: "Class '{0}' can't define static member '{1}' and have instance member '{2}.{1}' with the same name."
correctionMessage: "Try renaming the member to a name that doesn't conflict."
comment: |-
10.11 Class Member Conflicts: Let `C` be a class. It is a compile-time
error if `C` declares a static member with basename `n`, and has an
instance member with basename `n`.
Parameters:
0: the name of the class defining the conflicting member
1: the name of the conflicting static member
2: the name of the class defining the field with which the method conflicts
CONFLICTING_TYPE_VARIABLE_AND_CLASS:
sharedName: CONFLICTING_TYPE_VARIABLE_AND_CONTAINER
problemMessage: "'{0}' can't be used to name both a type variable and the class in which the type variable is defined."
correctionMessage: Try renaming either the type variable or the class.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the type variable
documentation: |-
#### Description
The analyzer produces this diagnostic when a class, mixin, or extension
declaration declares a type parameter with the same name as the class,
mixin, or extension that declares it.
#### Example
The following code produces this diagnostic because the type parameter `C`
has the same name as the class `C` of which it's a part:
```dart
class C<[!C!]> {}
```
#### Common fixes
Rename either the type parameter, or the class, mixin, or extension:
```dart
class C<T> {}
```
CONFLICTING_TYPE_VARIABLE_AND_ENUM:
sharedName: CONFLICTING_TYPE_VARIABLE_AND_CONTAINER
problemMessage: "'{0}' can't be used to name both a type variable and the enum in which the type variable is defined."
correctionMessage: Try renaming either the type variable or the enum.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the type variable
CONFLICTING_TYPE_VARIABLE_AND_EXTENSION:
sharedName: CONFLICTING_TYPE_VARIABLE_AND_CONTAINER
problemMessage: "'{0}' can't be used to name both a type variable and the extension in which the type variable is defined."
correctionMessage: Try renaming either the type variable or the extension.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the type variable
CONFLICTING_TYPE_VARIABLE_AND_MIXIN:
sharedName: CONFLICTING_TYPE_VARIABLE_AND_CONTAINER
problemMessage: "'{0}' can't be used to name both a type variable and the mixin in which the type variable is defined."
correctionMessage: Try renaming either the type variable or the mixin.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the type variable
CONFLICTING_TYPE_VARIABLE_AND_MEMBER_CLASS:
sharedName: CONFLICTING_TYPE_VARIABLE_AND_MEMBER
problemMessage: "'{0}' can't be used to name both a type variable and a member in this class."
correctionMessage: Try renaming either the type variable or the member.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the type variable
documentation: |-
#### Description
The analyzer produces this diagnostic when a class, mixin, or extension
declaration declares a type parameter with the same name as one of the
members of the class, mixin, or extension that declares it.
#### Example
The following code produces this diagnostic because the type parameter `T`
has the same name as the field `T`:
```dart
class C<[!T!]> {
int T = 0;
}
```
#### Common fixes
Rename either the type parameter or the member with which it conflicts:
```dart
class C<T> {
int total = 0;
}
```
CONFLICTING_TYPE_VARIABLE_AND_MEMBER_MIXIN:
sharedName: CONFLICTING_TYPE_VARIABLE_AND_MEMBER
problemMessage: "'{0}' can't be used to name both a type variable and a member in this mixin."
correctionMessage: Try renaming either the type variable or the member.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the type variable
CONFLICTING_TYPE_VARIABLE_AND_MEMBER_ENUM:
sharedName: CONFLICTING_TYPE_VARIABLE_AND_MEMBER
problemMessage: "'{0}' can't be used to name both a type variable and a member in this enum."
correctionMessage: Try renaming either the type variable or the member.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the type variable
CONFLICTING_TYPE_VARIABLE_AND_MEMBER_EXTENSION:
sharedName: CONFLICTING_TYPE_VARIABLE_AND_MEMBER
problemMessage: "'{0}' can't be used to name both a type variable and a member in this extension."
correctionMessage: Try renaming either the type variable or the member.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the type variable
CONST_CONSTRUCTOR_FIELD_TYPE_MISMATCH:
problemMessage: "In a const constructor, a value of type '{0}' can't be assigned to the field '{1}', which has type '{2}'."
correctionMessage: "Try using a subtype, or removing the keyword 'const'."
comment: |-
16.12.2 Const: It is a compile-time error if evaluation of a constant
object results in an uncaught exception being thrown.
Parameters:
0: the type of the runtime value of the argument
1: the name of the field
2: the type of the field
CONST_CONSTRUCTOR_CONSTANT_FROM_DEFERRED_LIBRARY:
sharedName: COLLECTION_ELEMENT_FROM_DEFERRED_LIBRARY
problemMessage: "Constant values from a deferred library can't be used as values in a 'const' constructor."
correctionMessage: "Try removing the keyword 'const' from the constructor or removing the keyword 'deferred' from the import."
hasPublishedDocs: true
comment: No parameters.
CONST_CONSTRUCTOR_PARAM_TYPE_MISMATCH:
problemMessage: "A value of type '{0}' can't be assigned to a parameter of type '{1}' in a const constructor."
correctionMessage: "Try using a subtype, or removing the keyword 'const'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the type of the runtime value of the argument
1: the static type of the parameter
documentation: |-
#### Description
The analyzer produces this diagnostic when the runtime type of a constant
value can't be assigned to the static type of a constant constructor's
parameter.
#### Example
The following code produces this diagnostic because the runtime type of `i`
is `int`, which can't be assigned to the static type of `s`:
```dart
class C {
final String s;
const C(this.s);
}
const dynamic i = 0;
void f() {
const C([!i!]);
}
```
#### Common fixes
Pass a value of the correct type to the constructor:
```dart
class C {
final String s;
const C(this.s);
}
const dynamic i = 0;
void f() {
const C('$i');
}
```
CONST_CONSTRUCTOR_THROWS_EXCEPTION:
problemMessage: "Const constructors can't throw exceptions."
correctionMessage: "Try removing the throw statement, or removing the keyword 'const'."
comment: |-
16.12.2 Const: It is a compile-time error if evaluation of a constant
object results in an uncaught exception being thrown.
CONST_CONSTRUCTOR_WITH_FIELD_INITIALIZED_BY_NON_CONST:
problemMessage: "Can't define the 'const' constructor because the field '{0}' is initialized with a non-constant value."
correctionMessage: "Try initializing the field to a constant value, or removing the keyword 'const' from the constructor."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the field
documentation: |-
#### Description
The analyzer produces this diagnostic when a constructor has the keyword
`const`, but a field in the class is initialized to a non-constant value.
#### Example
The following code produces this diagnostic because the field `s` is
initialized to a non-constant value:
```dart
String x = '3';
class C {
final String s = x;
[!const!] C();
}
```
#### Common fixes
If the field can be initialized to a constant value, then change the
initializer to a constant expression:
```dart
class C {
final String s = '3';
const C();
}
```
If the field can't be initialized to a constant value, then remove the
keyword `const` from the constructor:
```dart
String x = '3';
class C {
final String s = x;
C();
}
```
CONST_CONSTRUCTOR_WITH_MIXIN_WITH_FIELD:
problemMessage: "This constructor can't be declared 'const' because a mixin adds the instance field: {0}."
correctionMessage: "Try removing the 'const' keyword or removing the 'with' clause from the class declaration, or removing the field from the mixin class."
comment: |-
7.6.3 Constant Constructors: The superinitializer that appears, explicitly
or implicitly, in the initializer list of a constant constructor must
specify a constant constructor of the superclass of the immediately
enclosing class or a compile-time error occurs.
12.1 Mixin Application: For each generative constructor named ... an
implicitly declared constructor named ... is declared. If Sq is a
generative const constructor, and M does not declare any fields, Cq is
also a const constructor.
Parameters:
0: the name of the instance field.
CONST_CONSTRUCTOR_WITH_MIXIN_WITH_FIELDS:
sharedName: CONST_CONSTRUCTOR_WITH_MIXIN_WITH_FIELD
problemMessage: "This constructor can't be declared 'const' because the mixins add the instance fields: {0}."
correctionMessage: "Try removing the 'const' keyword or removing the 'with' clause from the class declaration, or removing the fields from the mixin classes."
comment: |-
7.6.3 Constant Constructors: The superinitializer that appears, explicitly
or implicitly, in the initializer list of a constant constructor must
specify a constant constructor of the superclass of the immediately
enclosing class or a compile-time error occurs.
12.1 Mixin Application: For each generative constructor named ... an
implicitly declared constructor named ... is declared. If Sq is a
generative const constructor, and M does not declare any fields, Cq is
also a const constructor.
Parameters:
0: the names of the instance fields.
CONST_CONSTRUCTOR_WITH_NON_CONST_SUPER:
problemMessage: "A constant constructor can't call a non-constant super constructor of '{0}'."
correctionMessage: "Try calling a constant constructor in the superclass, or removing the keyword 'const' from the constructor."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the superclass
documentation: |-
#### Description
The analyzer produces this diagnostic when a constructor that is marked as
`const` invokes a constructor from its superclass that isn't marked as
`const`.
#### Example
The following code produces this diagnostic because the `const` constructor
in `B` invokes the constructor `nonConst` from the class `A`, and the
superclass constructor isn't a `const` constructor:
```dart
class A {
const A();
A.nonConst();
}
class B extends A {
const B() : [!super.nonConst()!];
}
```
#### Common fixes
If it isn't essential to invoke the superclass constructor that is
currently being invoked, then invoke a constant constructor from the
superclass:
```dart
class A {
const A();
A.nonConst();
}
class B extends A {
const B() : super();
}
```
If it's essential that the current constructor be invoked and if you can
modify it, then add `const` to the constructor in the superclass:
```dart
class A {
const A();
const A.nonConst();
}
class B extends A {
const B() : super.nonConst();
}
```
If it's essential that the current constructor be invoked and you can't
modify it, then remove `const` from the constructor in the subclass:
```dart
class A {
const A();
A.nonConst();
}
class B extends A {
B() : super.nonConst();
}
```
CONST_CONSTRUCTOR_WITH_NON_FINAL_FIELD:
problemMessage: "Can't define a const constructor for a class with non-final fields."
correctionMessage: "Try making all of the fields final, or removing the keyword 'const' from the constructor."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a constructor is marked as a
const constructor, but the constructor is defined in a class that has at
least one non-final instance field (either directly or by inheritance).
#### Example
The following code produces this diagnostic because the field `x` isn't
final:
```dart
class C {
int x;
const [!C!](this.x);
}
```
#### Common fixes
If it's possible to mark all of the fields as final, then do so:
```dart
class C {
final int x;
const C(this.x);
}
```
If it isn't possible to mark all of the fields as final, then remove the
keyword `const` from the constructor:
```dart
class C {
int x;
C(this.x);
}
```
CONST_DEFERRED_CLASS:
problemMessage: "Deferred classes can't be created with 'const'."
correctionMessage: "Try using 'new' to create the instance, or changing the import to not be deferred."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a class from a library that is
imported using a deferred import is used to create a `const` object.
Constants are evaluated at compile time, and classes from deferred
libraries aren't available at compile time.
For more information, check out
[Lazily loading a library](https://dart.dev/language/libraries#lazily-loading-a-library).
#### Example
The following code produces this diagnostic because it attempts to create a
`const` instance of a class from a deferred library:
```dart
import 'dart:convert' deferred as convert;
const json2 = [!convert.JsonCodec()!];
```
#### Common fixes
If the object isn't required to be a constant, then change the code so that
a non-constant instance is created:
```dart
import 'dart:convert' deferred as convert;
final json2 = convert.JsonCodec();
```
If the object must be a constant, then remove `deferred` from the import
directive:
```dart
import 'dart:convert' as convert;
const json2 = convert.JsonCodec();
```
CONST_EVAL_ASSERTION_FAILURE:
problemMessage: "The assertion in this constant expression failed."
CONST_EVAL_EXTENSION_METHOD:
problemMessage: "Extension methods can't be used in constant expressions."
CONST_EVAL_FOR_ELEMENT:
problemMessage: "Constant expressions don't support 'for' elements."
correctionMessage: "Try replacing the 'for' element with a spread, or removing 'const'."
CONST_EVAL_METHOD_INVOCATION:
problemMessage: "Methods can't be invoked in constant expressions."
CONST_EVAL_THROWS_EXCEPTION:
problemMessage: Evaluation of this constant expression throws an exception.
comment: |-
16.12.2 Const: It is a compile-time error if evaluation of a constant
object results in an uncaught exception being thrown.
CONST_EVAL_THROWS_IDBZE:
problemMessage: Evaluation of this constant expression throws an IntegerDivisionByZeroException.
comment: |-
16.12.2 Const: It is a compile-time error if evaluation of a constant
object results in an uncaught exception being thrown.
CONST_EVAL_TYPE_BOOL:
problemMessage: "In constant expressions, operands of this operator must be of type 'bool'."
comment: |-
16.12.2 Const: An expression of one of the forms !e, e1 && e2 or e1 || e2,
where e, e1 and e2 are constant expressions that evaluate to a boolean
value.
CONST_EVAL_TYPE_BOOL_INT:
problemMessage: "In constant expressions, operands of this operator must be of type 'bool' or 'int'."
comment: |-
16.12.2 Const: An expression of one of the forms !e, e1 && e2 or e1 || e2,
where e, e1 and e2 are constant expressions that evaluate to a boolean
value.
CONST_EVAL_TYPE_BOOL_NUM_STRING:
problemMessage: "In constant expressions, operands of this operator must be of type 'bool', 'num', 'String' or 'null'."
comment: |-
16.12.2 Const: An expression of one of the forms e1 == e2 or e1 != e2 where
e1 and e2 are constant expressions that evaluate to a numeric, string or
boolean value or to null.
CONST_EVAL_TYPE_INT:
problemMessage: "In constant expressions, operands of this operator must be of type 'int'."
comment: |-
16.12.2 Const: An expression of one of the forms ~e, e1 ^ e2, e1 & e2,
e1 | e2, e1 >> e2 or e1 << e2, where e, e1 and e2 are constant expressions
that evaluate to an integer value or to null.
CONST_EVAL_TYPE_NUM:
problemMessage: "In constant expressions, operands of this operator must be of type 'num'."
comment: |-
16.12.2 Const: An expression of one of the forms e, e1 + e2, e1 - e2, e1
e2, e1 / e2, e1 ~/ e2, e1 > e2, e1 < e2, e1 >= e2, e1 <= e2 or e1 % e2,
where e, e1 and e2 are constant expressions that evaluate to a numeric
value or to null.
CONST_EVAL_TYPE_TYPE:
problemMessage: "In constant expressions, operands of this operator must be of type 'Type'."
CONST_INITIALIZED_WITH_NON_CONSTANT_VALUE:
problemMessage: Const variables must be initialized with a constant value.
correctionMessage: Try changing the initializer to be a constant expression.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a value that isn't statically
known to be a constant is assigned to a variable that's declared to be a
`const` variable.
#### Example
The following code produces this diagnostic because `x` isn't declared to
be `const`:
```dart
var x = 0;
const y = [!x!];
```
#### Common fixes
If the value being assigned can be declared to be `const`, then change the
declaration:
```dart
const x = 0;
const y = x;
```
If the value can't be declared to be `const`, then remove the `const`
modifier from the variable, possibly using `final` in its place:
```dart
var x = 0;
final y = x;
```
CONST_INITIALIZED_WITH_NON_CONSTANT_VALUE_FROM_DEFERRED_LIBRARY:
problemMessage: "Constant values from a deferred library can't be used to initialize a 'const' variable."
correctionMessage: Try initializing the variable without referencing members of the deferred library, or changing the import to not be deferred.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a `const` variable is
initialized using a `const` variable from a library that is imported using
a deferred import. Constants are evaluated at compile time, and values from
deferred libraries aren't available at compile time.
For more information, check out
[Lazily loading a library](https://dart.dev/language/libraries#lazily-loading-a-library).
#### Example
The following code produces this diagnostic because the variable `pi` is
being initialized using the constant `math.pi` from the library
`dart:math`, and `dart:math` is imported as a deferred library:
```dart
import 'dart:math' deferred as math;
const pi = math.[!pi!];
```
#### Common fixes
If you need to reference the value of the constant from the imported
library, then remove the keyword `deferred`:
```dart
import 'dart:math' as math;
const pi = math.pi;
```
If you don't need to reference the imported constant, then remove the
reference:
```dart
const pi = 3.14;
```
CONST_INSTANCE_FIELD:
problemMessage: Only static fields can be declared as const.
correctionMessage: "Try declaring the field as final, or adding the keyword 'static'."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when an instance field is marked as
being const.
#### Example
The following code produces this diagnostic because `f` is an instance
field:
```dart
class C {
[!const!] int f = 3;
}
```
#### Common fixes
If the field needs to be an instance field, then remove the keyword
`const`, or replace it with `final`:
```dart
class C {
final int f = 3;
}
```
If the field really should be a const field, then make it a static field:
```dart
class C {
static const int f = 3;
}
```
CONST_MAP_KEY_NOT_PRIMITIVE_EQUALITY:
problemMessage: "The type of a key in a constant map can't override the '==' operator, or 'hashCode', but the class '{0}' does."
correctionMessage: "Try using a different value for the key, or removing the keyword 'const' from the map."
hasPublishedDocs: true
comment: |-
Parameters:
0: the type of the entry's key
documentation: |-
#### Description
The analyzer produces this diagnostic when the class of object used as a
key in a constant map literal implements either the `==` operator, the
getter `hashCode`, or both. The implementation of constant maps uses both
the `==` operator and the `hashCode` getter, so any implementation other
than the ones inherited from `Object` requires executing arbitrary code at
compile time, which isn't supported.
#### Examples
The following code produces this diagnostic because the constant map
contains a key whose type is `C`, and the class `C` overrides the
implementation of `==`:
```dart
class C {
const C();
bool operator ==(Object other) => true;
}
const map = {[!C()!] : 0};
```
The following code produces this diagnostic because the constant map
contains a key whose type is `C`, and the class `C` overrides the
implementation of `hashCode`:
```dart
class C {
const C();
int get hashCode => 3;
}
const map = {[!C()!] : 0};
```
#### Common fixes
If you can remove the implementation of `==` and `hashCode` from the
class, then do so:
```dart
class C {
const C();
}
const map = {C() : 0};
```
If you can't remove the implementation of `==` and `hashCode` from the
class, then make the map non-constant:
```dart
class C {
const C();
bool operator ==(Object other) => true;
}
final map = {C() : 0};
```
CONST_NOT_INITIALIZED:
problemMessage: "The constant '{0}' must be initialized."
correctionMessage: Try adding an initialization to the declaration.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the uninitialized final variable
documentation: |-
#### Description
The analyzer produces this diagnostic when a variable that is declared to
be a constant doesn't have an initializer.
#### Example
The following code produces this diagnostic because `c` isn't initialized:
```dart
const [!c!];
```
#### Common fixes
Add an initializer:
```dart
const c = 'c';
```
CONST_SET_ELEMENT_NOT_PRIMITIVE_EQUALITY:
problemMessage: "An element in a constant set can't override the '==' operator, or 'hashCode', but the type '{0}' does."
correctionMessage: "Try using a different value for the element, or removing the keyword 'const' from the set."
previousName: CONST_SET_ELEMENT_TYPE_IMPLEMENTS_EQUALS
hasPublishedDocs: true
comment: |-
Parameters:
0: the type of the element
documentation: |-
#### Description
The analyzer produces this diagnostic when the class of object used as an
element in a constant set literal implements either the `==` operator, the
getter `hashCode`, or both. The implementation of constant sets uses both
the `==` operator and the `hashCode` getter, so any implementation other
than the ones inherited from `Object` requires executing arbitrary code at
compile time, which isn't supported.
#### Example
The following code produces this diagnostic because the constant set
contains an element whose type is `C`, and the class `C` overrides the
implementation of `==`:
```dart
class C {
const C();
bool operator ==(Object other) => true;
}
const set = {[!C()!]};
```
The following code produces this diagnostic because the constant set
contains an element whose type is `C`, and the class `C` overrides the
implementation of `hashCode`:
```dart
class C {
const C();
int get hashCode => 3;
}
const map = {[!C()!]};
```
#### Common fixes
If you can remove the implementation of `==` and `hashCode` from the
class, then do so:
```dart
class C {
const C();
}
const set = {C()};
```
If you can't remove the implementation of `==` and `hashCode` from the
class, then make the set non-constant:
```dart
class C {
const C();
bool operator ==(Object other) => true;
}
final set = {C()};
```
CONST_SPREAD_EXPECTED_LIST_OR_SET:
problemMessage: A list or a set is expected in this spread.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the expression of a spread
operator in a constant list or set evaluates to something other than a list
or a set.
#### Example
The following code produces this diagnostic because the value of `list1` is
`null`, which is neither a list nor a set:
```dart
%language=2.9
const List<int> list1 = null;
const List<int> list2 = [...[!list1!]];
```
#### Common fixes
Change the expression to something that evaluates to either a constant list
or a constant set:
```dart
%language=2.9
const List<int> list1 = [];
const List<int> list2 = [...list1];
```
CONST_SPREAD_EXPECTED_MAP:
problemMessage: A map is expected in this spread.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the expression of a spread
operator in a constant map evaluates to something other than a map.
#### Example
The following code produces this diagnostic because the value of `map1` is
`null`, which isn't a map:
```dart
%language=2.9
const Map<String, int> map1 = null;
const Map<String, int> map2 = {...[!map1!]};
```
#### Common fixes
Change the expression to something that evaluates to a constant map:
```dart
%language=2.9
const Map<String, int> map1 = {};
const Map<String, int> map2 = {...map1};
```
CONST_WITH_NON_CONST:
problemMessage: "The constructor being called isn't a const constructor."
correctionMessage: "Try removing 'const' from the constructor invocation."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the keyword `const` is used to
invoke a constructor that isn't marked with `const`.
#### Example
The following code produces this diagnostic because the constructor in `A`
isn't a const constructor:
```dart
class A {
A();
}
A f() => [!const!] A();
```
#### Common fixes
If it's desirable and possible to make the class a constant class (by
making all of the fields of the class, including inherited fields, final),
then add the keyword `const` to the constructor:
```dart
class A {
const A();
}
A f() => const A();
```
Otherwise, remove the keyword `const`:
```dart
class A {
A();
}
A f() => A();
```
CONST_WITH_NON_CONSTANT_ARGUMENT:
problemMessage: Arguments of a constant creation must be constant expressions.
correctionMessage: "Try making the argument a valid constant, or use 'new' to call the constructor."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a const constructor is invoked
with an argument that isn't a constant expression.
#### Example
The following code produces this diagnostic because `i` isn't a constant:
```dart
class C {
final int i;
const C(this.i);
}
C f(int i) => const C([!i!]);
```
#### Common fixes
Either make all of the arguments constant expressions, or remove the
`const` keyword to use the non-constant form of the constructor:
```dart
class C {
final int i;
const C(this.i);
}
C f(int i) => C(i);
```
CONST_WITH_TYPE_PARAMETERS:
problemMessage: "A constant creation can't use a type parameter as a type argument."
correctionMessage: Try replacing the type parameter with a different type.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a type parameter is used as a
type argument in a `const` invocation of a constructor. This isn't allowed
because the value of the type parameter (the actual type that will be used
at runtime) can't be known at compile time.
#### Example
The following code produces this diagnostic because the type parameter `T`
is being used as a type argument when creating a constant:
```dart
class C<T> {
const C();
}
C<T> newC<T>() => const C<[!T!]>();
```
#### Common fixes
If the type that will be used for the type parameter can be known at
compile time, then remove the use of the type parameter:
```dart
class C<T> {
const C();
}
C<int> newC() => const C<int>();
```
If the type that will be used for the type parameter can't be known until
runtime, then remove the keyword `const`:
```dart
class C<T> {
const C();
}
C<T> newC<T>() => C<T>();
```
CONST_WITH_TYPE_PARAMETERS_CONSTRUCTOR_TEAROFF:
sharedName: CONST_WITH_TYPE_PARAMETERS
problemMessage: "A constant constructor tearoff can't use a type parameter as a type argument."
correctionMessage: Try replacing the type parameter with a different type.
hasPublishedDocs: true
comment: No parameters.
CONST_WITH_TYPE_PARAMETERS_FUNCTION_TEAROFF:
sharedName: CONST_WITH_TYPE_PARAMETERS
problemMessage: "A constant function tearoff can't use a type parameter as a type argument."
correctionMessage: Try replacing the type parameter with a different type.
hasPublishedDocs: true
comment: No parameters.
CONST_WITH_UNDEFINED_CONSTRUCTOR:
problemMessage: "The class '{0}' doesn't have a constant constructor '{1}'."
correctionMessage: Try calling a different constructor.
comment: |-
16.12.2 Const: It is a compile-time error if <i>T.id</i> is not the name of
a constant constructor declared by the type <i>T</i>.
Parameters:
0: the name of the type
1: the name of the requested constant constructor
CONST_WITH_UNDEFINED_CONSTRUCTOR_DEFAULT:
problemMessage: "The class '{0}' doesn't have an unnamed constant constructor."
correctionMessage: Try calling a different constructor.
comment: |-
16.12.2 Const: It is a compile-time error if <i>T.id</i> is not the name of
a constant constructor declared by the type <i>T</i>.
Parameters:
0: the name of the type
CONSTANT_PATTERN_WITH_NON_CONSTANT_EXPRESSION:
problemMessage: The expression of a constant pattern must be a valid constant.
correctionMessage: Try making the expression a valid constant.
comment: No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a constant pattern has an
expression that isn't a valid constant.
#### Example
The following code produces this diagnostic because the constant pattern
`i` isn't a constant:
```dart
void f(int e, int i) {
switch (e) {
case [!i!]:
break;
}
}
```
#### Common fixes
If the value that should be matched is known, then replace the expression
with a constant:
```dart
void f(int e, int i) {
switch (e) {
case 0:
break;
}
}
```
If the value that should be matched isn't known, then rewrite the code to
not use a pattern:
```dart
void f(int e, int i) {
if (e == i) {}
}
```
CONTINUE_LABEL_INVALID:
previousName: CONTINUE_LABEL_ON_SWITCH
hasPublishedDocs: true
problemMessage: The label used in a 'continue' statement must be defined on either a loop or a switch member.
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the label in a `continue`
statement resolves to a label on a `switch` statement.
#### Example
The following code produces this diagnostic because the label `l`, used to
label a `switch` statement, is used in the `continue` statement:
```dart
void f(int i) {
l: switch (i) {
case 0:
[!continue l;!]
}
}
```
#### Common fixes
Find a different way to achieve the control flow you need; for example, by
introducing a loop that re-executes the `switch` statement.
COULD_NOT_INFER:
problemMessage: "Couldn't infer type parameter '{0}'.{1}"
comment: |-
Parameters:
0: the name of the type parameter
1: detail text explaining why the type could not be inferred
NEW_WITH_NON_TYPE:
sharedName: CREATION_WITH_NON_TYPE
problemMessage: "The name '{0}' isn't a class."
correctionMessage: Try correcting the name to match an existing class.
isUnresolvedIdentifier: true
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the non-type element
documentation: |-
#### Description
The analyzer produces this diagnostic when an instance creation using
either `new` or `const` specifies a name that isn't defined as a class.
#### Example
The following code produces this diagnostic because `f` is a function
rather than a class:
```dart
int f() => 0;
void g() {
new [!f!]();
}
```
#### Common fixes
If a class should be created, then replace the invalid name with the name
of a valid class:
```dart
int f() => 0;
void g() {
new Object();
}
```
If the name is the name of a function and you want that function to be
invoked, then remove the `new` or `const` keyword:
```dart
int f() => 0;
void g() {
f();
}
```
CONST_WITH_NON_TYPE:
sharedName: CREATION_WITH_NON_TYPE
problemMessage: "The name '{0}' isn't a class."
correctionMessage: Try correcting the name to match an existing class.
isUnresolvedIdentifier: true
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the non-type element
DEFAULT_LIST_CONSTRUCTOR:
problemMessage: "The default 'List' constructor isn't available when null safety is enabled."
correctionMessage: "Try using a list literal, 'List.filled' or 'List.generate'."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when it finds a use of the default
constructor for the class `List` in code that has opted in to null safety.
#### Example
Assuming the following code is opted in to null safety, it produces this
diagnostic because it uses the default `List` constructor:
```dart
var l = [!List<int>!]();
```
#### Common fixes
If no initial size is provided, then convert the code to use a list
literal:
```dart
var l = <int>[];
```
If an initial size needs to be provided and there is a single reasonable
initial value for the elements, then use `List.filled`:
```dart
var l = List.filled(3, 0);
```
If an initial size needs to be provided but each element needs to be
computed, then use `List.generate`:
```dart
var l = List.generate(3, (i) => i);
```
DEFAULT_VALUE_IN_REDIRECTING_FACTORY_CONSTRUCTOR:
problemMessage: "Default values aren't allowed in factory constructors that redirect to another constructor."
correctionMessage: Try removing the default value.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a factory constructor that
redirects to another constructor specifies a default value for an optional
parameter.
#### Example
The following code produces this diagnostic because the factory constructor
in `A` has a default value for the optional parameter `x`:
```dart
class A {
factory A([int [!x!] = 0]) = B;
}
class B implements A {
B([int x = 1]) {}
}
```
#### Common fixes
Remove the default value from the factory constructor:
```dart
class A {
factory A([int x]) = B;
}
class B implements A {
B([int x = 1]) {}
}
```
Note that this fix might change the value used when the optional parameter
is omitted. If that happens, and if that change is a problem, then consider
making the optional parameter a required parameter in the factory method:
```dart
class A {
factory A(int x) = B;
}
class B implements A {
B([int x = 1]) {}
}
```
DEFAULT_VALUE_ON_REQUIRED_PARAMETER:
problemMessage: "Required named parameters can't have a default value."
correctionMessage: "Try removing either the default value or the 'required' modifier."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a named parameter has both the
`required` modifier and a default value. If the parameter is required, then
a value for the parameter is always provided at the call sites, so the
default value can never be used.
#### Example
The following code generates this diagnostic:
```dart
void log({required String [!message!] = 'no message'}) {}
```
#### Common fixes
If the parameter is really required, then remove the default value:
```dart
void log({required String message}) {}
```
If the parameter isn't always required, then remove the `required`
modifier:
```dart
void log({String message = 'no message'}) {}
```
DEFERRED_IMPORT_OF_EXTENSION:
problemMessage: Imports of deferred libraries must hide all extensions.
correctionMessage: Try adding either a show combinator listing the names you need to reference or a hide combinator listing all of the extensions.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a library that is imported using
a deferred import declares an extension that is visible in the importing
library. Extension methods are resolved at compile time, and extensions
from deferred libraries aren't available at compile time.
For more information, check out
[Lazily loading a library](https://dart.dev/language/libraries#lazily-loading-a-library).
#### Example
Given a file `a.dart` that defines a named extension:
```dart
%uri="lib/a.dart"
class C {}
extension E on String {
int get size => length;
}
```
The following code produces this diagnostic because the named extension is
visible to the library:
```dart
import [!'a.dart'!] deferred as a;
void f() {
a.C();
}
```
#### Common fixes
If the library must be imported as `deferred`, then either add a `show`
clause listing the names being referenced or add a `hide` clause listing
all of the named extensions. Adding a `show` clause would look like this:
```dart
import 'a.dart' deferred as a show C;
void f() {
a.C();
}
```
Adding a `hide` clause would look like this:
```dart
import 'a.dart' deferred as a hide E;
void f() {
a.C();
}
```
With the first fix, the benefit is that if new extensions are added to the
imported library, then the extensions won't cause a diagnostic to be
generated.
If the library doesn't need to be imported as `deferred`, or if you need to
make use of the extension method declared in it, then remove the keyword
`deferred`:
```dart
import 'a.dart' as a;
void f() {
a.C();
}
```
DEFINITELY_UNASSIGNED_LATE_LOCAL_VARIABLE:
problemMessage: "The late local variable '{0}' is definitely unassigned at this point."
correctionMessage: Ensure that it is assigned on necessary execution paths.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the variable that is invalid
documentation: |-
#### Description
The analyzer produces this diagnostic when [definite assignment][] analysis
shows that a local variable that's marked as `late` is read before being
assigned.
#### Example
The following code produces this diagnostic because `x` wasn't assigned a
value before being read:
```dart
void f(bool b) {
late int x;
print([!x!]);
}
```
#### Common fixes
Assign a value to the variable before reading from it:
```dart
void f(bool b) {
late int x;
x = b ? 1 : 0;
print(x);
}
```
DISALLOWED_TYPE_INSTANTIATION_EXPRESSION:
problemMessage: Only a generic type, generic function, generic instance method, or generic constructor can have type arguments.
correctionMessage: Try removing the type arguments, or instantiating the type(s) of a generic type, generic function, generic instance method, or generic constructor.
comment: No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when an expression with a value that
is anything other than one of the allowed kinds of values is followed by
type arguments. The allowed kinds of values are:
- generic types,
- generic constructors, and
- generic functions, including top-level functions, static and instance
members, and local functions.
#### Example
The following code produces this diagnostic because `i` is a top-level
variable, which isn't one of the allowed cases:
```dart
int i = 1;
void f() {
print([!i!]<int>);
}
```
#### Common fixes
If the referenced value is correct, then remove the type arguments:
```dart
int i = 1;
void f() {
print(i);
}
```
DUPLICATE_AUGMENTATION_IMPORT:
problemMessage: "The library already contains an augmentation with the URI '{0}'."
correctionMessage: Try removing all except one of the duplicated augmentation directives.
comment: |-
Parameters:
0: the URI of the duplicate augmentation
DUPLICATE_CONSTRUCTOR_NAME:
sharedName: DUPLICATE_CONSTRUCTOR
problemMessage: "The constructor with name '{0}' is already defined."
correctionMessage: Try renaming one of the constructors.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the duplicate entity
DUPLICATE_CONSTRUCTOR_DEFAULT:
sharedName: DUPLICATE_CONSTRUCTOR
problemMessage: The unnamed constructor is already defined.
correctionMessage: Try giving one of the constructors a name.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a class declares more than one
unnamed constructor or when it declares more than one constructor with the
same name.
#### Examples
The following code produces this diagnostic because there are two
declarations for the unnamed constructor:
```dart
class C {
C();
[!C!]();
}
```
The following code produces this diagnostic because there are two
declarations for the constructor named `m`:
```dart
class C {
C.m();
[!C.m!]();
}
```
#### Common fixes
If there are multiple unnamed constructors and all of the constructors are
needed, then give all of them, or all except one of them, a name:
```dart
class C {
C();
C.n();
}
```
If there are multiple unnamed constructors and all except one of them are
unneeded, then remove the constructors that aren't needed:
```dart
class C {
C();
}
```
If there are multiple named constructors and all of the constructors are
needed, then rename all except one of them:
```dart
class C {
C.m();
C.n();
}
```
If there are multiple named constructors and all except one of them are
unneeded, then remove the constructors that aren't needed:
```dart
class C {
C.m();
}
```
DUPLICATE_DEFINITION:
problemMessage: "The name '{0}' is already defined."
correctionMessage: Try renaming one of the declarations.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the duplicate entity
documentation: |-
#### Description
The analyzer produces this diagnostic when a name is declared, and there is
a previous declaration with the same name in the same scope.
#### Example
The following code produces this diagnostic because the name `x` is
declared twice:
```dart
int x = 0;
int [!x!] = 1;
```
#### Common fixes
Choose a different name for one of the declarations.
```dart
int x = 0;
int y = 1;
```
DUPLICATE_FIELD_NAME:
problemMessage: The field name '{0}' is already used in this record.
correctionMessage: Try renaming the field.
hasPublishedDocs: true
comment: |-
Parameters:
0: the duplicated name
documentation: |-
#### Description
The analyzer produces this diagnostic when either a record literal or a
record type annotation contains a field whose name is the same as a
previously declared field in the same literal or type.
#### Examples
The following code produces this diagnostic because the record literal has
two fields named `a`:
```dart
var r = (a: 1, [!a!]: 2);
```
The following code produces this diagnostic because the record type
annotation has two fields named `a`, one a positional field and the other
a named field:
```dart
void f((int a, {int [!a!]}) r) {}
```
#### Common fixes
Rename one or both of the fields:
```dart
var r = (a: 1, b: 2);
```
DUPLICATE_FIELD_FORMAL_PARAMETER:
problemMessage: "The field '{0}' can't be initialized by multiple parameters in the same constructor."
correctionMessage: Try removing one of the parameters, or using different fields.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the field
documentation: |-
#### Description
The analyzer produces this diagnostic when there's more than one
initializing formal parameter for the same field in a constructor's
parameter list. It isn't useful to assign a value that will immediately be
overwritten.
#### Example
The following code produces this diagnostic because `this.f` appears twice
in the parameter list:
```dart
class C {
int f;
C(this.f, this.[!f!]) {}
}
```
#### Common fixes
Remove one of the initializing formal parameters:
```dart
class C {
int f;
C(this.f) {}
}
```
DUPLICATE_NAMED_ARGUMENT:
problemMessage: "The argument for the named parameter '{0}' was already specified."
correctionMessage: Try removing one of the named arguments, or correcting one of the names to reference a different named parameter.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the parameter that was duplicated
documentation: |-
#### Description
The analyzer produces this diagnostic when an invocation has two or more
named arguments that have the same name.
#### Example
The following code produces this diagnostic because there are two arguments
with the name `a`:
```dart
%language=2.9
void f(C c) {
c.m(a: 0, [!a!]: 1);
}
class C {
void m({int a, int b}) {}
}
```
#### Common fixes
If one of the arguments should have a different name, then change the name:
```dart
%language=2.9
void f(C c) {
c.m(a: 0, b: 1);
}
class C {
void m({int a, int b}) {}
}
```
If one of the arguments is wrong, then remove it:
```dart
%language=2.9
void f(C c) {
c.m(a: 1);
}
class C {
void m({int a, int b}) {}
}
```
DUPLICATE_PART:
problemMessage: "The library already contains a part with the URI '{0}'."
correctionMessage: Try removing all except one of the duplicated part directives.
hasPublishedDocs: true
comment: |-
Parameters:
0: the URI of the duplicate part
documentation: |-
#### Description
The analyzer produces this diagnostic when a single file is referenced in
multiple part directives.
#### Example
Given a file `part.dart` containing
```dart
%uri="lib/part.dart"
part of lib;
```
The following code produces this diagnostic because the file `part.dart` is
included multiple times:
```dart
library lib;
part 'part.dart';
part [!'part.dart'!];
```
#### Common fixes
Remove all except the first of the duplicated part directives:
```dart
library lib;
part 'part.dart';
```
DUPLICATE_PATTERN_ASSIGNMENT_VARIABLE:
problemMessage: The variable '{0}' is already assigned in this pattern.
correctionMessage: Try renaming the variable.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the variable
documentation: |-
#### Description
The analyzer produces this diagnostic when a single pattern variable is
assigned a value more than once in the same pattern assignment.
#### Example
The following code produces this diagnostic because the variable `a` is
assigned twice in the pattern `(a, a)`:
```dart
int f((int, int) r) {
int a;
(a, [!a!]) = r;
return a;
}
```
#### Common fixes
If you need to capture all of the values, then use a unique variable for
each of the subpatterns being matched:
```dart
int f((int, int) r) {
int a, b;
(a, b) = r;
return a + b;
}
```
If some of the values don't need to be captured, then use a wildcard
pattern `_` to avoid having to bind the value to a variable:
```dart
int f((int, int) r) {
int a;
(_, a) = r;
return a;
}
```
DUPLICATE_PATTERN_FIELD:
problemMessage: The field '{0}' is already matched in this pattern.
correctionMessage: Try removing the duplicate field.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the field
documentation: |-
#### Description
The analyzer produces this diagnostic when a record pattern matches the
same field more than once, or when an object pattern matches the same
getter more than once.
#### Examples
The following code produces this diagnostic because the record field `a`
is matched twice in the same record pattern:
```dart
void f(({int a, int b}) r) {
switch (r) {
case (a: 1, [!a!]: 2):
return;
}
}
```
The following code produces this diagnostic because the getter `f` is
matched twice in the same object pattern:
```dart
void f(Object o) {
switch (o) {
case C(f: 1, [!f!]: 2):
return;
}
}
class C {
int? f;
}
```
#### Common fixes
If the pattern should match for more than one value of the duplicated
field, then use a logical-or pattern:
```dart
void f(({int a, int b}) r) {
switch (r) {
case (a: 1, b: _) || (a: 2, b: _):
break;
}
}
```
If the pattern should match against multiple fields, then change the name
of one of the fields:
```dart
void f(({int a, int b}) r) {
switch (r) {
case (a: 1, b: 2):
return;
}
}
```
DUPLICATE_REST_ELEMENT_IN_PATTERN:
problemMessage: At most one rest element is allowed in a list or map pattern.
correctionMessage: Try removing the duplicate rest element.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when there's more than one rest
pattern in either a list or map pattern. A rest pattern will capture any
values unmatched by other subpatterns, making subsequent rest patterns
unnecessary because there's nothing left to capture.
#### Example
The following code produces this diagnostic because there are two rest
patterns in the list pattern:
```dart
void f(List<int> x) {
if (x case [0, ..., [!...!]]) {}
}
```
#### Common fixes
Remove all but one of the rest patterns:
```dart
void f(List<int> x) {
if (x case [0, ...]) {}
}
```
DUPLICATE_VARIABLE_PATTERN:
problemMessage: The variable '{0}' is already defined in this pattern.
correctionMessage: Try renaming the variable.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the variable
documentation: |-
#### Description
The analyzer produces this diagnostic when a branch of a logical-and
pattern declares a variable that is already declared in an earlier branch
of the same pattern.
#### Example
The following code produces this diagnostic because the variable `a` is
declared in both branches of the logical-and pattern:
```dart
void f((int, int) r) {
if (r case (var a, 0) && (0, var [!a!])) {
print(a);
}
}
```
#### Common fixes
If you need to capture the matched value in multiple branches, then change
the names of the variables so that they are unique:
```dart
void f((int, int) r) {
if (r case (var a, 0) && (0, var b)) {
print(a + b);
}
}
```
If you only need to capture the matched value on one branch, then remove
the variable pattern from all but one branch:
```dart
void f((int, int) r) {
if (r case (var a, 0) && (0, _)) {
print(a);
}
}
```
EMPTY_MAP_PATTERN:
problemMessage: A map pattern must have at least one entry.
correctionMessage: Try replacing it with an object pattern 'Map()'.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a map pattern is empty.
#### Example
The following code produces this diagnostic because the map pattern
is empty:
```dart
void f(Map<int, String> x) {
if (x case [!{}!]) {}
}
```
#### Common fixes
If the pattern should match any map, then replace it with an object
pattern:
```dart
void f(Map<int, String> x) {
if (x case Map()) {}
}
```
If the pattern should only match an empty map, then check the length
in the pattern:
```dart
void f(Map<int, String> x) {
if (x case Map(isEmpty: true)) {}
}
```
ENUM_CONSTANT_SAME_NAME_AS_ENCLOSING:
problemMessage: "The name of the enum constant can't be the same as the enum's name."
correctionMessage: Try renaming the constant.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when an enum constant has the same
name as the enum in which it's declared.
#### Example
The following code produces this diagnostic because the enum constant `E`
has the same name as the enclosing enum `E`:
```dart
enum E {
[!E!]
}
```
#### Common fixes
If the name of the enum is correct, then rename the constant:
```dart
enum E {
e
}
```
If the name of the constant is correct, then rename the enum:
```dart
enum F {
E
}
```
ENUM_CONSTANT_WITH_NON_CONST_CONSTRUCTOR:
problemMessage: The invoked constructor isn't a 'const' constructor.
correctionMessage: Try invoking a 'const' generative constructor.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when an enum constant is being
created using either a factory constructor or a generative constructor
that isn't marked as being `const`.
#### Example
The following code produces this diagnostic because the enum constant `e`
is being initialized by a factory constructor:
```dart
enum E {
[!e!]();
factory E() => e;
}
```
#### Common fixes
Use a generative constructor marked as `const`:
```dart
enum E {
e._();
factory E() => e;
const E._();
}
```
ENUM_INSTANTIATED_TO_BOUNDS_IS_NOT_WELL_BOUNDED:
problemMessage: The result of instantiating the enum to bounds is not well-bounded.
correctionMessage: Try using different bounds for type parameters.
ENUM_MIXIN_WITH_INSTANCE_VARIABLE:
problemMessage: Mixins applied to enums can't have instance variables.
correctionMessage: Try replacing the instance variables with getters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a mixin that's applied to an
enum declares one or more instance variables. This isn't allowed because
the enum constants are constant, and there isn't any way for the
constructor in the enum to initialize any of the mixin's fields.
#### Example
The following code produces this diagnostic because the mixin `M` defines
the instance field `x`:
```dart
mixin M {
int x = 0;
}
enum E with [!M!] {
a
}
```
#### Common fixes
If you need to apply the mixin, then change all instance fields into
getter and setter pairs and implement them in the enum if necessary:
```dart
mixin M {
int get x => 0;
}
enum E with M {
a
}
```
If you don't need to apply the mixin, then remove it:
```dart
enum E {
a
}
```
ENUM_WITH_ABSTRACT_MEMBER:
problemMessage: "'{0}' must have a method body because '{1}' is an enum."
correctionMessage: "Try adding a body to '{0}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the abstract method
1: the name of the enclosing enum
documentation: |-
#### Description
The analyzer produces this diagnostic when a member of an enum is found
that doesn't have a concrete implementation. Enums aren't allowed to
contain abstract members.
#### Example
The following code produces this diagnostic because `m` is an abstract
method and `E` is an enum:
```dart
enum E {
e;
[!void m();!]
}
```
#### Common fixes
Provide an implementation for the member:
```dart
enum E {
e;
void m() {}
}
```
ENUM_WITH_NAME_VALUES:
problemMessage: The name 'values' is not a valid name for an enum.
correctionMessage: Try using a different name.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when an enum is declared to have the
name `values`. This isn't allowed because the enum has an implicit static
field named `values`, and the two would collide.
#### Example
The following code produces this diagnostic because there's an enum
declaration that has the name `values`:
```dart
enum [!values!] {
c
}
```
#### Common fixes
Rename the enum to something other than `values`.
EQUAL_ELEMENTS_IN_CONST_SET:
problemMessage: "Two elements in a constant set literal can't be equal."
correctionMessage: Change or remove the duplicate element.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when two elements in a constant set
literal have the same value. The set can only contain each value once,
which means that one of the values is unnecessary.
#### Example
The following code produces this diagnostic because the string `'a'` is
specified twice:
```dart
const Set<String> set = {'a', [!'a'!]};
```
#### Common fixes
Remove one of the duplicate values:
```dart
const Set<String> set = {'a'};
```
Note that literal sets preserve the order of their elements, so the choice
of which element to remove might affect the order in which elements are
returned by an iterator.
EQUAL_KEYS_IN_CONST_MAP:
problemMessage: "Two keys in a constant map literal can't be equal."
correctionMessage: Change or remove the duplicate key.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a key in a constant map is the
same as a previous key in the same map. If two keys are the same, then the
second value would overwrite the first value, which makes having both pairs
pointless.
#### Example
The following code produces this diagnostic because the key `1` is used
twice:
```dart
const map = <int, String>{1: 'a', 2: 'b', [!1!]: 'c', 4: 'd'};
```
#### Common fixes
If both entries should be included in the map, then change one of the keys
to be different:
```dart
const map = <int, String>{1: 'a', 2: 'b', 3: 'c', 4: 'd'};
```
If only one of the entries is needed, then remove the one that isn't
needed:
```dart
const map = <int, String>{1: 'a', 2: 'b', 4: 'd'};
```
Note that literal maps preserve the order of their entries, so the choice
of which entry to remove might affect the order in which keys and values
are returned by an iterator.
EQUAL_KEYS_IN_MAP_PATTERN:
problemMessage: Two keys in a map pattern can't be equal.
correctionMessage: Change or remove the duplicate key.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a map pattern contains more
than one key with the same name. The same key can't be matched twice.
#### Example
The following code produces this diagnostic because the key `'a'` appears
twice:
```dart
void f(Map<String, int> x) {
if (x case {'a': 1, [!'a'!]: 2}) {}
}
```
#### Common fixes
If you are trying to match two different keys, then change one of the keys
in the pattern:
```dart
void f(Map<String, int> x) {
if (x case {'a': 1, 'b': 2}) {}
}
```
If you are trying to match the same key, but allow any one of multiple
patterns to match, the use a logical-or pattern:
```dart
void f(Map<String, int> x) {
if (x case {'a': 1 || 2}) {}
}
```
EXPECTED_ONE_LIST_PATTERN_TYPE_ARGUMENTS:
problemMessage: List patterns require one type argument or none, but {0} found.
correctionMessage: Try adjusting the number of type arguments.
hasPublishedDocs: true
comment: |-
Parameters:
0: the number of provided type arguments
documentation: |-
#### Description
The analyzer produces this diagnostic when a list pattern has more than
one type argument. List patterns can have either zero type arguments or
one type argument, but can't have more than one.
#### Example
The following code produces this diagnostic because the list pattern
(`[0]`) has two type arguments:
```dart
void f(Object x) {
if (x case [!<int, int>!][0]) {}
}
```
#### Common fixes
Remove all but one of the type arguments:
```dart
void f(Object x) {
if (x case <int>[0]) {}
}
```
EXPECTED_ONE_LIST_TYPE_ARGUMENTS:
problemMessage: "List literals require one type argument or none, but {0} found."
correctionMessage: Try adjusting the number of type arguments.
hasPublishedDocs: true
comment: |-
Parameters:
0: the number of provided type arguments
documentation: |-
#### Description
The analyzer produces this diagnostic when a list literal has more than one
type argument.
#### Example
The following code produces this diagnostic because the list literal has
two type arguments when it can have at most one:
```dart
var l = [!<int, int>!][];
```
#### Common fixes
Remove all except one of the type arguments:
```dart
var l = <int>[];
```
EXPECTED_ONE_SET_TYPE_ARGUMENTS:
problemMessage: "Set literals require one type argument or none, but {0} were found."
correctionMessage: Try adjusting the number of type arguments.
hasPublishedDocs: true
comment: |-
Parameters:
0: the number of provided type arguments
documentation: |-
#### Description
The analyzer produces this diagnostic when a set literal has more than one
type argument.
#### Example
The following code produces this diagnostic because the set literal has
three type arguments when it can have at most one:
```dart
var s = [!<int, String, int>!]{0, 'a', 1};
```
#### Common fixes
Remove all except one of the type arguments:
```dart
var s = <int>{0, 1};
```
EXPECTED_TWO_MAP_TYPE_ARGUMENTS:
problemMessage: "Map literals require two type arguments or none, but {0} found."
correctionMessage: Try adjusting the number of type arguments.
hasPublishedDocs: true
comment: |-
Parameters:
0: the number of provided type arguments
documentation: |-
#### Description
The analyzer produces this diagnostic when a map literal has either one or
more than two type arguments.
#### Example
The following code produces this diagnostic because the map literal has
three type arguments when it can have either two or zero:
```dart
var m = [!<int, String, int>!]{};
```
#### Common fixes
Remove all except two of the type arguments:
```dart
var m = <int, String>{};
```
EXPECTED_TWO_MAP_PATTERN_TYPE_ARGUMENTS:
problemMessage: Map patterns require two type arguments or none, but {0} found.
correctionMessage: Try adjusting the number of type arguments.
hasPublishedDocs: true
comment: |-
Parameters:
0: the number of provided type arguments
documentation: |-
#### Description
The analyzer produces this diagnostic when a map pattern has either one
type argument or more than two type arguments. Map patterns can have
either two type arguments or zero type arguments, but can't have any other
number.
#### Example
The following code produces this diagnostic because the map pattern
(`<int>{}`) has one type argument:
```dart
void f(Object x) {
if (x case [!<int>!]{0: _}) {}
}
```
#### Common fixes
Add or remove type arguments until there are two, or none:
```dart
void f(Object x) {
if (x case <int, int>{0: _}) {}
}
```
EXPORT_INTERNAL_LIBRARY:
problemMessage: "The library '{0}' is internal and can't be exported."
hasPublishedDocs: true
comment: |-
Parameters:
0: the URI pointing to a library
documentation: |-
#### Description
The analyzer produces this diagnostic when it finds an export whose `dart:`
URI references an internal library.
#### Example
The following code produces this diagnostic because `_interceptors` is an
internal library:
```dart
export [!'dart:_interceptors'!];
```
#### Common fixes
Remove the export directive.
EXPORT_LEGACY_SYMBOL:
problemMessage: "The symbol '{0}' is defined in a legacy library, and can't be re-exported from a library with null safety enabled."
correctionMessage: Try removing the export or migrating the legacy library.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of a symbol defined in a legacy library
documentation: |-
#### Description
The analyzer produces this diagnostic when a library that was opted in to
null safety exports another library, and the exported library is opted out
of null safety.
#### Example
Given a library that is opted out of null safety:
```dart
%uri="lib/optedOut.dart"
// @dart = 2.8
String s;
```
The following code produces this diagnostic because it's exporting symbols
from an opted-out library:
```dart
export [!'optedOut.dart'!];
class C {}
```
#### Common fixes
If you're able to do so, migrate the exported library so that it doesn't
need to opt out:
```dart
String? s;
```
If you can't migrate the library, then remove the export:
```dart
class C {}
```
If the exported library (the one that is opted out) itself exports an
opted-in library, then it's valid for your library to indirectly export the
symbols from the opted-in library. You can do so by adding a hide
combinator to the export directive in your library that hides all of the
names declared in the opted-out library.
EXPORT_OF_NON_LIBRARY:
problemMessage: "The exported library '{0}' can't have a part-of directive."
correctionMessage: Try exporting the library that the part is a part of.
hasPublishedDocs: true
comment: |-
Parameters:
0: the URI pointing to a non-library declaration
documentation: |-
#### Description
The analyzer produces this diagnostic when an export directive references a
part rather than a library.
#### Example
Given a file `part.dart` containing
```dart
%uri="lib/part.dart"
part of lib;
```
The following code produces this diagnostic because the file `part.dart` is
a part, and only libraries can be exported:
```dart
library lib;
export [!'part.dart'!];
```
#### Common fixes
Either remove the export directive, or change the URI to be the URI of the
library containing the part.
EXPRESSION_IN_MAP:
problemMessage: "Expressions can't be used in a map literal."
correctionMessage: Try removing the expression or converting it to be a map entry.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the analyzer finds an
expression, rather than a map entry, in what appears to be a map literal.
#### Example
The following code produces this diagnostic:
```dart
var map = <String, int>{'a': 0, 'b': 1, [!'c'!]};
```
#### Common fixes
If the expression is intended to compute either a key or a value in an
entry, fix the issue by replacing the expression with the key or the value.
For example:
```dart
var map = <String, int>{'a': 0, 'b': 1, 'c': 2};
```
EXTENDS_NON_CLASS:
problemMessage: Classes can only extend other classes.
correctionMessage: Try specifying a different superclass, or removing the extends clause.
isUnresolvedIdentifier: true
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when an `extends` clause contains a
name that is declared to be something other than a class.
#### Example
The following code produces this diagnostic because `f` is declared to be a
function:
```dart
void f() {}
class C extends [!f!] {}
```
#### Common fixes
If you want the class to extend a class other than `Object`, then replace
the name in the `extends` clause with the name of that class:
```dart
void f() {}
class C extends B {}
class B {}
```
If you want the class to extend `Object`, then remove the `extends` clause:
```dart
void f() {}
class C {}
```
EXTENSION_AS_EXPRESSION:
problemMessage: "Extension '{0}' can't be used as an expression."
correctionMessage: Try replacing it with a valid expression.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the extension
documentation: |-
#### Description
The analyzer produces this diagnostic when the name of an extension is used
in an expression other than in an extension override or to qualify an
access to a static member of the extension. Because classes define a type,
the name of a class can be used to refer to the instance of `Type`
representing the type of the class. Extensions, on the other hand, don't
define a type and can't be used as a type literal.
#### Example
The following code produces this diagnostic because `E` is an extension:
```dart
extension E on int {
static String m() => '';
}
var x = [!E!];
```
#### Common fixes
Replace the name of the extension with a name that can be referenced, such
as a static member defined on the extension:
```dart
extension E on int {
static String m() => '';
}
var x = E.m();
```
EXTENSION_CONFLICTING_STATIC_AND_INSTANCE:
problemMessage: "An extension can't define static member '{0}' and an instance member with the same name."
correctionMessage: "Try renaming the member to a name that doesn't conflict."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the conflicting static member
documentation: |-
#### Description
The analyzer produces this diagnostic when an extension declaration
contains both an instance member and a static member that have the same
name. The instance member and the static member can't have the same name
because it's unclear which member is being referenced by an unqualified use
of the name within the body of the extension.
#### Example
The following code produces this diagnostic because the name `a` is being
used for two different members:
```dart
extension E on Object {
int get a => 0;
static int [!a!]() => 0;
}
```
#### Common fixes
Rename or remove one of the members:
```dart
extension E on Object {
int get a => 0;
static int b() => 0;
}
```
EXTENSION_DECLARES_MEMBER_OF_OBJECT:
problemMessage: "Extensions can't declare members with the same name as a member declared by 'Object'."
correctionMessage: Try specifying a different name for the member.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when an extension declaration
declares a member with the same name as a member declared in the class
`Object`. Such a member can never be used because the member in `Object` is
always found first.
#### Example
The following code produces this diagnostic because `toString` is defined
by `Object`:
```dart
extension E on String {
String [!toString!]() => this;
}
```
#### Common fixes
Remove the member or rename it so that the name doesn't conflict with the
member in `Object`:
```dart
extension E on String {
String displayString() => this;
}
```
EXTENSION_OVERRIDE_ACCESS_TO_STATIC_MEMBER:
problemMessage: "An extension override can't be used to access a static member from an extension."
correctionMessage: Try using just the name of the extension.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when an extension override is the
receiver of the invocation of a static member. Similar to static members in
classes, the static members of an extension should be accessed using the
name of the extension, not an extension override.
#### Example
The following code produces this diagnostic because `m` is static:
```dart
extension E on String {
static void m() {}
}
void f() {
E('').[!m!]();
}
```
#### Common fixes
Replace the extension override with the name of the extension:
```dart
extension E on String {
static void m() {}
}
void f() {
E.m();
}
```
EXTENSION_OVERRIDE_ARGUMENT_NOT_ASSIGNABLE:
problemMessage: "The type of the argument to the extension override '{0}' isn't assignable to the extended type '{1}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the type of the argument
1: the extended type
documentation: |-
#### Description
The analyzer produces this diagnostic when the argument to an extension
override isn't assignable to the type being extended by the extension.
#### Example
The following code produces this diagnostic because `3` isn't a `String`:
```dart
extension E on String {
void method() {}
}
void f() {
E([!3!]).method();
}
```
#### Common fixes
If you're using the correct extension, then update the argument to have the
correct type:
```dart
extension E on String {
void method() {}
}
void f() {
E(3.toString()).method();
}
```
If there's a different extension that's valid for the type of the argument,
then either replace the name of the extension or unwrap the argument so
that the correct extension is found.
EXTENSION_OVERRIDE_WITHOUT_ACCESS:
problemMessage: An extension override can only be used to access instance members.
correctionMessage: Consider adding an access to an instance member.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when an extension override is found
that isn't being used to access one of the members of the extension. The
extension override syntax doesn't have any runtime semantics; it only
controls which member is selected at compile time.
#### Example
The following code produces this diagnostic because `E(i)` isn't an
expression:
```dart
extension E on int {
int get a => 0;
}
void f(int i) {
print([!E(i)!]);
}
```
#### Common fixes
If you want to invoke one of the members of the extension, then add the
invocation:
```dart
extension E on int {
int get a => 0;
}
void f(int i) {
print(E(i).a);
}
```
If you don't want to invoke a member, then unwrap the argument:
```dart
extension E on int {
int get a => 0;
}
void f(int i) {
print(i);
}
```
EXTENSION_OVERRIDE_WITH_CASCADE:
problemMessage: "Extension overrides have no value so they can't be used as the receiver of a cascade expression."
correctionMessage: "Try using '.' instead of '..'."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when an extension override is used as
the receiver of a cascade expression. The value of a cascade expression
`e..m` is the value of the receiver `e`, but extension overrides aren't
expressions and don't have a value.
#### Example
The following code produces this diagnostic because `E(3)` isn't an
expression:
```dart
extension E on int {
void m() {}
}
f() {
[!E!](3)..m();
}
```
#### Common fixes
Use `.` rather than `..`:
```dart
extension E on int {
void m() {}
}
f() {
E(3).m();
}
```
If there are multiple cascaded accesses, you'll need to duplicate the
extension override for each one.
EXTENSION_TYPE_CONSTRUCTOR_WITH_SUPER_INVOCATION:
problemMessage: "Extension type constructors can't include superinitializers."
correctionMessage: Try removing the superconstructor invocation.
comment: No parameters.
EXTENSION_TYPE_DECLARES_INSTANCE_FIELD:
problemMessage: "Extension types can't declare instance fields."
correctionMessage: Try replacing the field with a getter.
comment: No parameters.
EXTENSION_TYPE_DECLARES_MEMBER_OF_OBJECT:
problemMessage: "Extension types can't declare members with the same name as a member declared by 'Object'."
correctionMessage: Try specifying a different name for the member.
comment: No parameters.
EXTENSION_TYPE_IMPLEMENTS_DISALLOWED_TYPE:
problemMessage: "Extension types can't implement '{0}'."
correctionMessage: Try specifying a different type, or remove the type from the list.
comment: |-
Parameters:
0: the display string of the disallowed type
EXTENSION_TYPE_INHERITED_MEMBER_CONFLICT:
problemMessage: "The extension type '{0}' has more than one distinct member named '{1}' from implemented types."
correctionMessage: Try redeclaring the corresponding member in this extension type.
comment: |-
Parameters:
0: the name of the extension type
1: the name of the conflicting member
EXTENSION_TYPE_REPRESENTATION_DEPENDS_ON_ITSELF:
problemMessage: "The extension type representation can't depend on itself."
correctionMessage: Try specifying a different type.
comment: No parameters.
EXTERNAL_FIELD_CONSTRUCTOR_INITIALIZER:
sharedName: EXTERNAL_WITH_INITIALIZER
problemMessage: External fields can't have initializers.
correctionMessage: "Try removing the field initializer or the 'external' keyword from the field declaration."
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a field or variable marked with
the keyword `external` has an initializer, or when an external field is
initialized in a constructor.
#### Examples
The following code produces this diagnostic because the external field `x`
is assigned a value in an initializer:
```dart
class C {
external int x;
C() : [!x!] = 0;
}
```
The following code produces this diagnostic because the external field `x`
has an initializer:
```dart
class C {
external final int [!x!] = 0;
}
```
The following code produces this diagnostic because the external top level
variable `x` has an initializer:
```dart
external final int [!x!] = 0;
```
#### Common fixes
Remove the initializer:
```dart
class C {
external final int x;
}
```
EXTERNAL_FIELD_INITIALIZER:
sharedName: EXTERNAL_WITH_INITIALIZER
problemMessage: External fields can't have initializers.
correctionMessage: "Try removing the initializer or the 'external' keyword."
hasPublishedDocs: true
EXTERNAL_VARIABLE_INITIALIZER:
sharedName: EXTERNAL_WITH_INITIALIZER
problemMessage: External variables can't have initializers.
correctionMessage: "Try removing the initializer or the 'external' keyword."
hasPublishedDocs: true
EXTRA_POSITIONAL_ARGUMENTS:
problemMessage: "Too many positional arguments: {0} expected, but {1} found."
correctionMessage: Try removing the extra arguments.
hasPublishedDocs: true
comment: |-
Parameters:
0: the maximum number of positional arguments
1: the actual number of positional arguments given
documentation: |-
#### Description
The analyzer produces this diagnostic when a method or function invocation
has more positional arguments than the method or function allows.
#### Example
The following code produces this diagnostic because `f` defines 2
parameters but is invoked with 3 arguments:
```dart
void f(int a, int b) {}
void g() {
f(1, 2, [!3!]);
}
```
#### Common fixes
Remove the arguments that don't correspond to parameters:
```dart
void f(int a, int b) {}
void g() {
f(1, 2);
}
```
EXTRA_POSITIONAL_ARGUMENTS_COULD_BE_NAMED:
problemMessage: "Too many positional arguments: {0} expected, but {1} found."
correctionMessage: Try removing the extra positional arguments, or specifying the name for named arguments.
hasPublishedDocs: true
comment: |-
Parameters:
0: the maximum number of positional arguments
1: the actual number of positional arguments given
documentation: |-
#### Description
The analyzer produces this diagnostic when a method or function invocation
has more positional arguments than the method or function allows, but the
method or function defines named parameters.
#### Example
The following code produces this diagnostic because `f` defines 2
positional parameters but has a named parameter that could be used for the
third argument:
```dart
%language=2.9
void f(int a, int b, {int c}) {}
void g() {
f(1, 2, [!3!]);
}
```
#### Common fixes
If some of the arguments should be values for named parameters, then add
the names before the arguments:
```dart
%language=2.9
void f(int a, int b, {int c}) {}
void g() {
f(1, 2, c: 3);
}
```
Otherwise, remove the arguments that don't correspond to positional
parameters:
```dart
%language=2.9
void f(int a, int b, {int c}) {}
void g() {
f(1, 2);
}
```
FIELD_INITIALIZED_BY_MULTIPLE_INITIALIZERS:
problemMessage: "The field '{0}' can't be initialized twice in the same constructor."
correctionMessage: Try removing one of the initializations.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the field being initialized multiple times
documentation: |-
#### Description
The analyzer produces this diagnostic when the initializer list of a
constructor initializes a field more than once. There is no value to allow
both initializers because only the last value is preserved.
#### Example
The following code produces this diagnostic because the field `f` is being
initialized twice:
```dart
class C {
int f;
C() : f = 0, [!f!] = 1;
}
```
#### Common fixes
Remove one of the initializers:
```dart
class C {
int f;
C() : f = 0;
}
```
FIELD_INITIALIZED_IN_INITIALIZER_AND_DECLARATION:
problemMessage: "Fields can't be initialized in the constructor if they are final and were already initialized at their declaration."
correctionMessage: Try removing one of the initializations.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a final field is initialized in
both the declaration of the field and in an initializer in a constructor.
Final fields can only be assigned once, so it can't be initialized in both
places.
#### Example
The following code produces this diagnostic because `f` is :
```dart
class C {
final int f = 0;
C() : [!f!] = 1;
}
```
#### Common fixes
If the initialization doesn't depend on any values passed to the
constructor, and if all of the constructors need to initialize the field to
the same value, then remove the initializer from the constructor:
```dart
class C {
final int f = 0;
C();
}
```
If the initialization depends on a value passed to the constructor, or if
different constructors need to initialize the field differently, then
remove the initializer in the field's declaration:
```dart
class C {
final int f;
C() : f = 1;
}
```
FIELD_INITIALIZED_IN_PARAMETER_AND_INITIALIZER:
problemMessage: "Fields can't be initialized in both the parameter list and the initializers."
correctionMessage: Try removing one of the initializations.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a field is initialized in both
the parameter list and in the initializer list of a constructor.
#### Example
The following code produces this diagnostic because the field `f` is
initialized both by an initializing formal parameter and in the
initializer list:
```dart
class C {
int f;
C(this.f) : [!f!] = 0;
}
```
#### Common fixes
If the field should be initialized by the parameter, then remove the
initialization in the initializer list:
```dart
class C {
int f;
C(this.f);
}
```
If the field should be initialized in the initializer list and the
parameter isn't needed, then remove the parameter:
```dart
class C {
int f;
C() : f = 0;
}
```
If the field should be initialized in the initializer list and the
parameter is needed, then make it a normal parameter:
```dart
class C {
int f;
C(int g) : f = g * 2;
}
```
FIELD_INITIALIZER_FACTORY_CONSTRUCTOR:
problemMessage: "Initializing formal parameters can't be used in factory constructors."
correctionMessage: Try using a normal parameter.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a factory constructor has an
initializing formal parameter. Factory constructors can't assign values to
fields because no instance is created; hence, there is no field to assign.
#### Example
The following code produces this diagnostic because the factory constructor
uses an initializing formal parameter:
```dart
class C {
int? f;
factory C([!this.f!]) => throw 0;
}
```
#### Common fixes
Replace the initializing formal parameter with a normal parameter:
```dart
class C {
int? f;
factory C(int f) => throw 0;
}
```
FIELD_INITIALIZER_NOT_ASSIGNABLE:
problemMessage: "The initializer type '{0}' can't be assigned to the field type '{1}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the type of the initializer expression
1: the name of the type of the field
documentation: |-
#### Description
The analyzer produces this diagnostic when the initializer list of a
constructor initializes a field to a value that isn't assignable to the
field.
#### Example
The following code produces this diagnostic because `0` has the type `int`,
and an `int` can't be assigned to a field of type `String`:
```dart
class C {
String s;
C() : s = [!0!];
}
```
#### Common fixes
If the type of the field is correct, then change the value assigned to it
so that the value has a valid type:
```dart
class C {
String s;
C() : s = '0';
}
```
If the type of the value is correct, then change the type of the field to
allow the assignment:
```dart
class C {
int s;
C() : s = 0;
}
```
CONST_FIELD_INITIALIZER_NOT_ASSIGNABLE:
sharedName: FIELD_INITIALIZER_NOT_ASSIGNABLE
problemMessage: "The initializer type '{0}' can't be assigned to the field type '{1}' in a const constructor."
correctionMessage: "Try using a subtype, or removing the 'const' keyword"
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the type of the initializer expression
1: the name of the type of the field
FIELD_INITIALIZER_OUTSIDE_CONSTRUCTOR:
problemMessage: Initializing formal parameters can only be used in constructors.
correctionMessage: Try using a normal parameter.
comment: |-
No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when an initializing formal
parameter is used in the parameter list for anything other than a
constructor.
#### Example
The following code produces this diagnostic because the initializing
formal parameter `this.x` is being used in the method `m`:
```dart
class A {
int x = 0;
m([[!this.x!] = 0]) {}
}
```
#### Common fixes
Replace the initializing formal parameter with a normal parameter and
assign the field within the body of the method:
```dart
class A {
int x = 0;
m([int x = 0]) {
this.x = x;
}
}
```
FIELD_INITIALIZER_REDIRECTING_CONSTRUCTOR:
problemMessage: "The redirecting constructor can't have a field initializer."
correctionMessage: Try initializing the field in the constructor being redirected to.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a redirecting constructor
initializes a field in the object. This isn't allowed because the instance
that has the field hasn't been created at the point at which it should be
initialized.
#### Examples
The following code produces this diagnostic because the constructor
`C.zero`, which redirects to the constructor `C`, has an initializing
formal parameter that initializes the field `f`:
```dart
class C {
int f;
C(this.f);
C.zero([!this.f!]) : this(f);
}
```
The following code produces this diagnostic because the constructor
`C.zero`, which redirects to the constructor `C`, has an initializer that
initializes the field `f`:
```dart
class C {
int f;
C(this.f);
C.zero() : [!f = 0!], this(1);
}
```
#### Common fixes
If the initialization is done by an initializing formal parameter, then
use a normal parameter:
```dart
class C {
int f;
C(this.f);
C.zero(int f) : this(f);
}
```
If the initialization is done in an initializer, then remove the
initializer:
```dart
class C {
int f;
C(this.f);
C.zero() : this(0);
}
```
FIELD_INITIALIZING_FORMAL_NOT_ASSIGNABLE:
problemMessage: "The parameter type '{0}' is incompatible with the field type '{1}'."
correctionMessage: "Try changing or removing the parameter's type, or changing the field's type."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the type of the field formal parameter
1: the name of the type of the field
documentation: |-
#### Description
The analyzer produces this diagnostic when the type of an initializing
formal parameter isn't assignable to the type of the field being
initialized.
#### Example
The following code produces this diagnostic because the initializing
formal parameter has the type `String`, but the type of the field is
`int`. The parameter must have a type that is a subtype of the field's
type.
```dart
class C {
int f;
C([!String this.f!]);
}
```
#### Common fixes
If the type of the field is incorrect, then change the type of the field to
match the type of the parameter, and consider removing the type from the
parameter:
```dart
class C {
String f;
C(this.f);
}
```
If the type of the parameter is incorrect, then remove the type of the
parameter:
```dart
class C {
int f;
C(this.f);
}
```
If the types of both the field and the parameter are correct, then use an
initializer rather than an initializing formal parameter to convert the
parameter value into a value of the correct type:
```dart
class C {
int f;
C(String s) : f = int.parse(s);
}
```
FINAL_CLASS_EXTENDED_OUTSIDE_OF_LIBRARY:
sharedName: INVALID_USE_OF_TYPE_OUTSIDE_LIBRARY
problemMessage: "The class '{0}' can't be extended outside of its library because it's a final class."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the final class being extended.
FINAL_CLASS_IMPLEMENTED_OUTSIDE_OF_LIBRARY:
sharedName: INVALID_USE_OF_TYPE_OUTSIDE_LIBRARY
problemMessage: "The class '{0}' can't be implemented outside of its library because it's a final class."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the final class being implemented.
FINAL_CLASS_USED_AS_MIXIN_CONSTRAINT_OUTSIDE_OF_LIBRARY:
sharedName: INVALID_USE_OF_TYPE_OUTSIDE_LIBRARY
problemMessage: "The class '{0}' can't be used as a mixin superclass constraint outside of its library because it's a final class."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the final class being used as a mixin superclass constraint.
FINAL_INITIALIZED_IN_DECLARATION_AND_CONSTRUCTOR:
problemMessage: "'{0}' is final and was given a value when it was declared, so it can't be set to a new value."
correctionMessage: Try removing one of the initializations.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the field in question
documentation: |-
#### Description
The analyzer produces this diagnostic when a final field is initialized
twice: once where it's declared and once by a constructor's parameter.
#### Example
The following code produces this diagnostic because the field `f` is
initialized twice:
```dart
class C {
final int f = 0;
C(this.[!f!]);
}
```
#### Common fixes
If the field should have the same value for all instances, then remove the
initialization in the parameter list:
```dart
class C {
final int f = 0;
C();
}
```
If the field can have different values in different instances, then remove
the initialization in the declaration:
```dart
class C {
final int f;
C(this.f);
}
```
FINAL_NOT_INITIALIZED:
problemMessage: "The final variable '{0}' must be initialized."
correctionMessage: Try initializing the variable.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the uninitialized final variable
documentation: |-
#### Description
The analyzer produces this diagnostic when a final field or variable isn't
initialized.
#### Example
The following code produces this diagnostic because `x` doesn't have an
initializer:
```dart
final [!x!];
```
#### Common fixes
For variables and static fields, you can add an initializer:
```dart
final x = 0;
```
For instance fields, you can add an initializer as shown in the previous
example, or you can initialize the field in every constructor. You can
initialize the field by using an initializing formal parameter:
```dart
class C {
final int x;
C(this.x);
}
```
You can also initialize the field by using an initializer in the
constructor:
```dart
class C {
final int x;
C(int y) : x = y * 2;
}
```
FINAL_NOT_INITIALIZED_CONSTRUCTOR_1:
sharedName: FINAL_NOT_INITIALIZED_CONSTRUCTOR
problemMessage: "All final variables must be initialized, but '{0}' isn't."
correctionMessage: Try adding an initializer for the field.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the uninitialized final variable
documentation: |-
#### Description
The analyzer produces this diagnostic when a class defines one or more
final instance fields without initializers and has at least one constructor
that doesn't initialize those fields. All final instance fields must be
initialized when the instance is created, either by the field's initializer
or by the constructor.
#### Example
The following code produces this diagnostic:
```dart
class C {
final String value;
[!C!]();
}
```
#### Common fixes
If the value should be passed in to the constructor directly, then use an
initializing formal parameter to initialize the field `value`:
```dart
class C {
final String value;
C(this.value);
}
```
If the value should be computed indirectly from a value provided by the
caller, then add a parameter and include an initializer:
```dart
class C {
final String value;
C(Object o) : value = o.toString();
}
```
If the value of the field doesn't depend on values that can be passed to
the constructor, then add an initializer for the field as part of the field
declaration:
```dart
class C {
final String value = '';
C();
}
```
If the value of the field doesn't depend on values that can be passed to
the constructor but different constructors need to initialize it to
different values, then add an initializer for the field in the initializer
list:
```dart
class C {
final String value;
C() : value = '';
C.named() : value = 'c';
}
```
However, if the value is the same for all instances, then consider using a
static field instead of an instance field:
```dart
class C {
static const String value = '';
C();
}
```
FINAL_NOT_INITIALIZED_CONSTRUCTOR_2:
sharedName: FINAL_NOT_INITIALIZED_CONSTRUCTOR
problemMessage: "All final variables must be initialized, but '{0}' and '{1}' aren't."
correctionMessage: Try adding initializers for the fields.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the uninitialized final variable
1: the name of the uninitialized final variable
FINAL_NOT_INITIALIZED_CONSTRUCTOR_3_PLUS:
sharedName: FINAL_NOT_INITIALIZED_CONSTRUCTOR
problemMessage: "All final variables must be initialized, but '{0}', '{1}', and {2} others aren't."
correctionMessage: Try adding initializers for the fields.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the uninitialized final variable
1: the name of the uninitialized final variable
2: the number of additional not initialized variables that aren't listed
FOR_IN_OF_INVALID_ELEMENT_TYPE:
problemMessage: "The type '{0}' used in the 'for' loop must implement '{1}' with a type argument that can be assigned to '{2}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the type of the iterable expression.
1: the sequence type -- Iterable for `for` or Stream for `await for`.
2: the loop variable type.
documentation: |-
#### Description
The analyzer produces this diagnostic when the `Iterable` or `Stream` in a
for-in loop has an element type that can't be assigned to the loop
variable.
#### Example
The following code produces this diagnostic because `<String>[]` has an
element type of `String`, and `String` can't be assigned to the type of `e`
(`int`):
```dart
void f() {
for (int e in [!<String>[]!]) {
print(e);
}
}
```
#### Common fixes
If the type of the loop variable is correct, then update the type of the
iterable:
```dart
void f() {
for (int e in <int>[]) {
print(e);
}
}
```
If the type of the iterable is correct, then update the type of the loop
variable:
```dart
void f() {
for (String e in <String>[]) {
print(e);
}
}
```
FOR_IN_OF_INVALID_TYPE:
problemMessage: "The type '{0}' used in the 'for' loop must implement '{1}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the type of the iterable expression.
1: the sequence type -- Iterable for `for` or Stream for `await for`.
documentation: |-
#### Description
The analyzer produces this diagnostic when the expression following `in` in
a for-in loop has a type that isn't a subclass of `Iterable`.
#### Example
The following code produces this diagnostic because `m` is a `Map`, and
`Map` isn't a subclass of `Iterable`:
```dart
void f(Map<String, String> m) {
for (String s in [!m!]) {
print(s);
}
}
```
#### Common fixes
Replace the expression with one that produces an iterable value:
```dart
void f(Map<String, String> m) {
for (String s in m.values) {
print(s);
}
}
```
FOR_IN_WITH_CONST_VARIABLE:
problemMessage: "A for-in loop variable can't be a 'const'."
correctionMessage: "Try removing the 'const' modifier from the variable, or use a different variable."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the loop variable declared in a
for-in loop is declared to be a `const`. The variable can't be a `const`
because the value can't be computed at compile time.
#### Example
The following code produces this diagnostic because the loop variable `x`
is declared to be a `const`:
```dart
void f() {
for ([!const!] x in [0, 1, 2]) {
print(x);
}
}
```
#### Common fixes
If there's a type annotation, then remove the `const` modifier from the
declaration.
If there's no type, then replace the `const` modifier with `final`, `var`,
or a type annotation:
```dart
void f() {
for (final x in [0, 1, 2]) {
print(x);
}
}
```
GENERIC_FUNCTION_TYPE_CANNOT_BE_BOUND:
problemMessage: "Generic function types can't be used as type parameter bounds"
correctionMessage: Try making the free variable in the function type part of the larger declaration signature
comment: |-
It is a compile-time error if a generic function type is used as a bound
for a formal type parameter of a class or a function.
GENERIC_FUNCTION_TYPE_CANNOT_BE_TYPE_ARGUMENT:
problemMessage: "A generic function type can't be a type argument."
correctionMessage: "Try removing type parameters from the generic function type, or using 'dynamic' as the type argument here."
comment: |-
It is a compile-time error if a generic function type is used as an actual
type argument.
GENERIC_METHOD_TYPE_INSTANTIATION_ON_DYNAMIC:
problemMessage: "A method tear-off on a receiver whose type is 'dynamic' can't have type arguments."
correctionMessage: Specify the type of the receiver, or remove the type arguments from the method tear-off.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when an instance method is being torn
off from a receiver whose type is `dynamic`, and the tear-off includes type
arguments. Because the analyzer can't know how many type parameters the
method has, or whether it has any type parameters, there's no way it can
validate that the type arguments are correct. As a result, the type
arguments aren't allowed.
#### Example
The following code produces this diagnostic because the type of `p` is
`dynamic` and the tear-off of `m` has type arguments:
```dart
void f(dynamic list) {
[!list.fold!]<int>;
}
```
#### Common fixes
If you can use a more specific type than `dynamic`, then change the type of
the receiver:
```dart
void f(List<Object> list) {
list.fold<int>;
}
```
If you can't use a more specific type, then remove the type arguments:
```dart
void f(dynamic list) {
list.cast;
}
```
GETTER_NOT_ASSIGNABLE_SETTER_TYPES:
problemMessage: "The return type of getter '{0}' is '{1}' which isn't assignable to the type '{2}' of its setter '{3}'."
correctionMessage: Try changing the types so that they are compatible.
comment: |-
Parameters:
0: the name of the getter
1: the type of the getter
2: the type of the setter
3: the name of the setter
GETTER_NOT_SUBTYPE_SETTER_TYPES:
problemMessage: "The return type of getter '{0}' is '{1}' which isn't a subtype of the type '{2}' of its setter '{3}'."
correctionMessage: Try changing the types so that they are compatible.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the getter
1: the type of the getter
2: the type of the setter
3: the name of the setter
documentation: |-
#### Description
The analyzer produces this diagnostic when the return type of a getter
isn't a subtype of the type of the parameter of a setter with the same
name.
The subtype relationship is a requirement whether the getter and setter are
in the same class or whether one of them is in a superclass of the other.
#### Example
The following code produces this diagnostic because the return type of the
getter `x` is `num`, the parameter type of the setter `x` is `int`, and
`num` isn't a subtype of `int`:
```dart
class C {
num get [!x!] => 0;
set x(int y) {}
}
```
#### Common fixes
If the type of the getter is correct, then change the type of the setter:
```dart
class C {
num get x => 0;
set x(num y) {}
}
```
If the type of the setter is correct, then change the type of the getter:
```dart
class C {
int get x => 0;
set x(int y) {}
}
```
IF_ELEMENT_CONDITION_FROM_DEFERRED_LIBRARY:
problemMessage: "Constant values from a deferred library can't be used as values in an if condition inside a const collection literal."
correctionMessage: Try making the deferred import non-deferred.
ILLEGAL_ASYNC_GENERATOR_RETURN_TYPE:
problemMessage: "Functions marked 'async*' must have a return type that is a supertype of 'Stream<T>' for some type 'T'."
correctionMessage: "Try fixing the return type of the function, or removing the modifier 'async*' from the function body."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the body of a function has the
`async*` modifier even though the return type of the function isn't either
`Stream` or a supertype of `Stream`.
#### Example
The following code produces this diagnostic because the body of the
function `f` has the 'async*' modifier even though the return type `int`
isn't a supertype of `Stream`:
```dart
[!int!] f() async* {}
```
#### Common fixes
If the function should be asynchronous, then change the return type to be
either `Stream` or a supertype of `Stream`:
```dart
Stream<int> f() async* {}
```
If the function should be synchronous, then remove the `async*` modifier:
```dart
int f() => 0;
```
ILLEGAL_ASYNC_RETURN_TYPE:
problemMessage: "Functions marked 'async' must have a return type which is a supertype of 'Future'."
correctionMessage: "Try fixing the return type of the function, or removing the modifier 'async' from the function body."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the body of a function has the
`async` modifier even though the return type of the function isn't
assignable to `Future`.
#### Example
The following code produces this diagnostic because the body of the
function `f` has the `async` modifier even though the return type isn't
assignable to `Future`:
```dart
[!int!] f() async {
return 0;
}
```
#### Common fixes
If the function should be asynchronous, then change the return type to be
assignable to `Future`:
```dart
Future<int> f() async {
return 0;
}
```
If the function should be synchronous, then remove the `async` modifier:
```dart
int f() => 0;
```
ILLEGAL_ENUM_VALUES_DECLARATION:
sharedName: ILLEGAL_ENUM_VALUES
problemMessage: An instance member named 'values' can't be declared in a class that implements 'Enum'.
correctionMessage: Try using a different name.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when either a class that implements
`Enum` or a mixin with a superclass constraint of `Enum` has an instance
member named `values`.
#### Examples
The following code produces this diagnostic because the class `C`, which
implements `Enum`, declares an instance field named `values`:
```dart
abstract class C implements Enum {
int get [!values!] => 0;
}
```
The following code produces this diagnostic because the class `B`, which
implements `Enum`, inherits an instance method named `values` from `A`:
```dart
abstract class A {
int values() => 0;
}
abstract class [!B!] extends A implements Enum {}
```
#### Common fixes
Change the name of the conflicting member:
```dart
abstract class C implements Enum {
int get value => 0;
}
```
ILLEGAL_ENUM_VALUES_INHERITANCE:
sharedName: ILLEGAL_ENUM_VALUES
problemMessage: An instance member named 'values' can't be inherited from '{0}' in a class that implements 'Enum'.
correctionMessage: Try using a different name.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the class that declares 'values'
ILLEGAL_LANGUAGE_VERSION_OVERRIDE:
problemMessage: The language version must be {0}.
correctionMessage: Try removing the language version override and migrating the code.
comment: |-
Parameters:
0: the required language version
ILLEGAL_CONCRETE_ENUM_MEMBER_DECLARATION:
sharedName: ILLEGAL_CONCRETE_ENUM_MEMBER
problemMessage: A concrete instance member named '{0}' can't be declared in a class that implements 'Enum'.
correctionMessage: Try using a different name.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of member that cannot be declared
documentation: |-
#### Description
The analyzer produces this diagnostic when either an enum declaration, a
class that implements `Enum`, or a mixin with a superclass constraint of
`Enum`, declares or inherits a concrete instance member named either
`index`, `hashCode`, or `==`.
#### Examples
The following code produces this diagnostic because the enum `E` declares
an instance getter named `index`:
```dart
enum E {
v;
int get [!index!] => 0;
}
```
The following code produces this diagnostic because the class `C`, which
implements `Enum`, declares an instance field named `hashCode`:
```dart
abstract class C implements Enum {
int [!hashCode!] = 0;
}
```
The following code produces this diagnostic because the class `C`, which
indirectly implements `Enum` through the class `A`, declares an instance
getter named `hashCode`:
```dart
abstract class A implements Enum {}
abstract class C implements A {
int get [!hashCode!] => 0;
}
```
The following code produces this diagnostic because the mixin `M`, which
has `Enum` in the `on` clause, declares an explicit operator named `==`:
```dart
mixin M on Enum {
bool operator [!==!](Object? other) => false;
}
```
#### Common fixes
Rename the conflicting member:
```dart
enum E {
v;
int get getIndex => 0;
}
```
ILLEGAL_CONCRETE_ENUM_MEMBER_INHERITANCE:
sharedName: ILLEGAL_CONCRETE_ENUM_MEMBER
problemMessage: A concrete instance member named '{0}' can't be inherited from '{1}' in a class that implements 'Enum'.
correctionMessage: Try using a different name.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of member that cannot be inherited
1: the name of the class that declares the member
ILLEGAL_SYNC_GENERATOR_RETURN_TYPE:
problemMessage: "Functions marked 'sync*' must have a return type that is a supertype of 'Iterable<T>' for some type 'T'."
correctionMessage: "Try fixing the return type of the function, or removing the modifier 'sync*' from the function body."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the body of a function has the
`sync*` modifier even though the return type of the function isn't either
`Iterable` or a supertype of `Iterable`.
#### Example
The following code produces this diagnostic because the body of the
function `f` has the 'sync*' modifier even though the return type `int`
isn't a supertype of `Iterable`:
```dart
[!int!] f() sync* {}
```
#### Common fixes
If the function should return an iterable, then change the return type to
be either `Iterable` or a supertype of `Iterable`:
```dart
Iterable<int> f() sync* {}
```
If the function should return a single value, then remove the `sync*`
modifier:
```dart
int f() => 0;
```
IMPLEMENTS_NON_CLASS:
problemMessage: Classes and mixins can only implement other classes and mixins.
correctionMessage: Try specifying a class or mixin, or remove the name from the list.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a name used in the `implements`
clause of a class or mixin declaration is defined to be something other
than a class or mixin.
#### Example
The following code produces this diagnostic because `x` is a variable
rather than a class or mixin:
```dart
var x;
class C implements [!x!] {}
```
#### Common fixes
If the name is the name of an existing class or mixin that's already being
imported, then add a prefix to the import so that the local definition of
the name doesn't shadow the imported name.
If the name is the name of an existing class or mixin that isn't being
imported, then add an import, with a prefix, for the library in which it's
declared.
Otherwise, either replace the name in the `implements` clause with the name
of an existing class or mixin, or remove the name from the `implements`
clause.
IMPLEMENTS_REPEATED:
problemMessage: "'{0}' can only be implemented once."
correctionMessage: Try removing all but one occurrence of the class name.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the interface that is implemented more than once
documentation: |-
#### Description
The analyzer produces this diagnostic when a single class is specified more
than once in an `implements` clause.
#### Example
The following code produces this diagnostic because `A` is in the list
twice:
```dart
class A {}
class B implements A, [!A!] {}
```
#### Common fixes
Remove all except one occurrence of the class name:
```dart
class A {}
class B implements A {}
```
IMPLEMENTS_SUPER_CLASS:
problemMessage: "'{0}' can't be used in both the 'extends' and 'implements' clauses."
correctionMessage: Try removing one of the occurrences.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the class that appears in both "extends" and "implements"
clauses
documentation: |-
#### Description
The analyzer produces this diagnostic when a class is listed in the
`extends` clause of a class declaration and also in either the
`implements` or `with` clause of the same declaration.
#### Example
The following code produces this diagnostic because the class `A` is used
in both the `extends` and `implements` clauses for the class `B`:
```dart
class A {}
class B extends A implements [!A!] {}
```
The following code produces this diagnostic because the class `A` is used
in both the `extends` and `with` clauses for the class `B`:
```dart
mixin class A {}
class B extends A with [!A!] {}
```
#### Common fixes
If you want to inherit the implementation from the class, then remove the
class from the `implements` clause:
```dart
class A {}
class B extends A {}
```
If you don't want to inherit the implementation from the class, then remove
the `extends` clause:
```dart
class A {}
class B implements A {}
```
IMPLICIT_THIS_REFERENCE_IN_INITIALIZER:
problemMessage: "The instance member '{0}' can't be accessed in an initializer."
correctionMessage: Try replacing the reference to the instance member with a different expression
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the instance member
documentation: |-
#### Description
The analyzer produces this diagnostic when it finds a reference to an
instance member in a constructor's initializer list.
#### Example
The following code produces this diagnostic because `defaultX` is an
instance member:
```dart
class C {
int x;
C() : x = [!defaultX!];
int get defaultX => 0;
}
```
#### Common fixes
If the member can be made static, then do so:
```dart
class C {
int x;
C() : x = defaultX;
static int get defaultX => 0;
}
```
If not, then replace the reference in the initializer with a different
expression that doesn't use an instance member:
```dart
class C {
int x;
C() : x = 0;
int get defaultX => 0;
}
```
IMPLICIT_SUPER_INITIALIZER_MISSING_ARGUMENTS:
problemMessage: The implicitly invoked unnamed constructor from '{0}' has required parameters.
correctionMessage: Try adding an explicit super parameter with the required arguments.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the superclass
documentation: |-
#### Description
The analyzer produces this diagnostic when a constructor implicitly
invokes the unnamed constructor from the superclass, the unnamed
constructor of the superclass has a required parameter, and there's no
super parameter corresponding to the required parameter.
#### Examples
The following code produces this diagnostic because the unnamed
constructor in the class `B` implicitly invokes the unnamed constructor in
the class `A`, but the constructor in `A` has a required positional
parameter named `x`:
```dart
class A {
A(int x);
}
class B extends A {
[!B!]();
}
```
The following code produces this diagnostic because the unnamed
constructor in the class `B` implicitly invokes the unnamed constructor in
the class `A`, but the constructor in `A` has a required named parameter
named `x`:
```dart
class A {
A({required int x});
}
class B extends A {
[!B!]();
}
```
#### Common fixes
If you can add a parameter to the constructor in the subclass, then add a
super parameter corresponding to the required parameter in the superclass'
constructor. The new parameter can either be required:
```dart
class A {
A({required int x});
}
class B extends A {
B({required super.x});
}
```
or it can be optional:
```dart
class A {
A({required int x});
}
class B extends A {
B({super.x = 0});
}
```
If you can't add a parameter to the constructor in the subclass, then add
an explicit super constructor invocation with the required argument:
```dart
class A {
A(int x);
}
class B extends A {
B() : super(0);
}
```
IMPORT_INTERNAL_LIBRARY:
problemMessage: "The library '{0}' is internal and can't be imported."
hasPublishedDocs: true
comment: |-
Parameters:
0: the URI pointing to a library
documentation: |-
#### Description
The analyzer produces this diagnostic when it finds an import whose `dart:`
URI references an internal library.
#### Example
The following code produces this diagnostic because `_interceptors` is an
internal library:
```dart
import [!'dart:_interceptors'!];
```
#### Common fixes
Remove the import directive.
IMPORT_OF_NON_LIBRARY:
problemMessage: "The imported library '{0}' can't have a part-of directive."
correctionMessage: Try importing the library that the part is a part of.
comment: |-
Parameters:
0: the URI pointing to a non-library declaration
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a [part file][] is imported
into a library.
#### Example
Given a [part file][] named `part.dart` containing the following:
```dart
%uri="lib/part.dart"
part of lib;
```
The following code produces this diagnostic because imported files can't
have a part-of directive:
```dart
library lib;
import [!'part.dart'!];
```
#### Common fixes
Import the library that contains the [part file][] rather than the
[part file][] itself.
IMPORT_OF_NOT_AUGMENTATION:
problemMessage: "The imported file '{0}' isn't an augmentation of this library."
correctionMessage: Try adding a 'library augment' directive referencing this library to the imported file.
comment: |-
Parameters:
0: the URI of the imported file
INCONSISTENT_CASE_EXPRESSION_TYPES:
problemMessage: "Case expressions must have the same types, '{0}' isn't a '{1}'."
comment: |-
13.9 Switch: It is a compile-time error if values of the expressions
<i>e<sub>k</sub></i> are not instances of the same class <i>C</i>, for all
<i>1 &lt;= k &lt;= n</i>.
Parameters:
0: the expression source code that is the unexpected type
1: the name of the expected type
INCONSISTENT_INHERITANCE:
problemMessage: "Superinterfaces don't have a valid override for '{0}': {1}."
correctionMessage: Try adding an explicit override that is consistent with all of the inherited members.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the instance member with inconsistent inheritance.
1: the list of all inherited signatures for this member.
documentation: |-
#### Description
The analyzer produces this diagnostic when a class inherits two or more
conflicting signatures for a member and doesn't provide an implementation
that satisfies all the inherited signatures.
#### Example
The following code produces this diagnostic because `C` is inheriting the
declaration of `m` from `A`, and that implementation isn't consistent with
the signature of `m` that's inherited from `B`:
```dart
%language=2.9
class A {
void m({int a}) {}
}
class B {
void m({int b}) {}
}
class [!C!] extends A implements B {
}
```
#### Common fixes
Add an implementation of the method that satisfies all the inherited
signatures:
```dart
%language=2.9
class A {
void m({int a}) {}
}
class B {
void m({int b}) {}
}
class C extends A implements B {
void m({int a, int b}) {}
}
```
INCONSISTENT_INHERITANCE_GETTER_AND_METHOD:
problemMessage: "'{0}' is inherited as a getter (from '{1}') and also a method (from '{2}')."
correctionMessage: Try adjusting the supertypes of this class to remove the inconsistency.
comment: |-
11.1.1 Inheritance and Overriding. Let `I` be the implicit interface of a
class `C` declared in library `L`. `I` inherits all members of
`inherited(I, L)` and `I` overrides `m'` if `m' ∈ overrides(I, L)`. It is
a compile-time error if `m` is a method and `m'` is a getter, or if `m`
is a getter and `m'` is a method.
Parameters:
0: the name of the instance member with inconsistent inheritance.
1: the name of the superinterface that declares the name as a getter.
2: the name of the superinterface that declares the name as a method.
INCONSISTENT_LANGUAGE_VERSION_OVERRIDE:
problemMessage: Parts must have exactly the same language version override as the library.
comment: |-
No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a [part file][] has a language
version override comment that specifies a different language version than
the one being used for the library to which the part belongs.
#### Example
Given a [part file][] named `part.dart` that contains the following:
```dart
%uri="lib/part.dart"
// @dart = 2.14
part of 'test.dart';
```
The following code produces this diagnostic because the parts of a library
must have the same language version as the defining compilation unit:
```dart
// @dart = 2.15
part [!'part.dart'!];
```
#### Common fixes
Remove the language version override from the [part file][], so that it
implicitly uses the same version as the defining compilation unit:
```dart
%uri="lib/part.dart"
part of 'test.dart';
```
If necessary, either adjust the language version override in the defining
compilation unit to be appropriate for the code in the part, or migrate
the code in the [part file][] to be consistent with the new language
version.
INCONSISTENT_PATTERN_VARIABLE_LOGICAL_OR:
problemMessage: "The variable '{0}' has a different type and/or finality in this branch of the logical-or pattern."
correctionMessage: Try declaring the variable pattern with the same type and finality in both branches.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the pattern variable
documentation: |-
#### Description
The analyzer produces this diagnostic when a pattern variable that is
declared on all branches of a logical-or pattern doesn't have the same
type on every branch. It is also produced when the variable has a
different finality on different branches. A pattern variable declared on
multiple branches of a logical-or pattern is required to have the same
type and finality in each branch, so that the type and finality of the
variable can be known in code that's guarded by the logical-or pattern.
#### Examples
The following code produces this diagnostic because the variable `a` is
defined to be an `int` on one branch and a `double` on the other:
```dart
void f(Object? x) {
if (x case (int a) || (double [!a!])) {
print(a);
}
}
```
The following code produces this diagnostic because the variable `a` is
`final` in the first branch and isn't `final` in the second branch:
```dart
void f(Object? x) {
if (x case (final int a) || (int [!a!])) {
print(a);
}
}
```
#### Common fixes
If the finality of the variable is different, decide whether it should be
`final` or not `final` and make the cases consistent:
```dart
void f(Object? x) {
if (x case (int a) || (int a)) {
print(a);
}
}
```
If the type of the variable is different and the type isn't critical to
the condition being matched, then ensure that the variable has the same
type on both branches:
```dart
void f(Object? x) {
if (x case (num a) || (num a)) {
print(a);
}
}
```
If the type of the variable is different and the type is critical to the
condition being matched, then consider breaking the condition into
multiple `if` statements or `case` clauses:
```dart
void f(Object? x) {
if (x case int a) {
print(a);
} else if (x case double a) {
print(a);
}
}
```
INITIALIZER_FOR_NON_EXISTENT_FIELD:
problemMessage: "'{0}' isn't a field in the enclosing class."
correctionMessage: "Try correcting the name to match an existing field, or defining a field named '{0}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the initializing formal that is not an instance variable in
the immediately enclosing class
documentation: |-
#### Description
The analyzer produces this diagnostic when a constructor initializes a
field that isn't declared in the class containing the constructor.
Constructors can't initialize fields that aren't declared and fields that
are inherited from superclasses.
#### Example
The following code produces this diagnostic because the initializer is
initializing `x`, but `x` isn't a field in the class:
```dart
%language=2.9
class C {
int y;
C() : [!x = 0!];
}
```
#### Common fixes
If a different field should be initialized, then change the name to the
name of the field:
```dart
%language=2.9
class C {
int y;
C() : y = 0;
}
```
If the field must be declared, then add a declaration:
```dart
%language=2.9
class C {
int x;
int y;
C() : x = 0;
}
```
INITIALIZER_FOR_STATIC_FIELD:
problemMessage: "'{0}' is a static field in the enclosing class. Fields initialized in a constructor can't be static."
correctionMessage: Try removing the initialization.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the initializing formal that is a static variable in the
immediately enclosing class
documentation: |-
#### Description
The analyzer produces this diagnostic when a static field is initialized
in a constructor using either an initializing formal parameter or an
assignment in the initializer list.
#### Example
The following code produces this diagnostic because the static field `a`
is being initialized by the initializing formal parameter `this.a`:
```dart
class C {
static int? a;
C([!this.a!]);
}
```
#### Common fixes
If the field should be an instance field, then remove the keyword `static`:
```dart
class C {
int? a;
C(this.a);
}
```
If you intended to initialize an instance field and typed the wrong name,
then correct the name of the field being initialized:
```dart
class C {
static int? a;
int? b;
C(this.b);
}
```
If you really want to initialize the static field, then move the
initialization into the constructor body:
```dart
class C {
static int? a;
C(int? c) {
a = c;
}
}
```
INITIALIZING_FORMAL_FOR_NON_EXISTENT_FIELD:
problemMessage: "'{0}' isn't a field in the enclosing class."
correctionMessage: "Try correcting the name to match an existing field, or defining a field named '{0}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the initializing formal that is not an instance variable in
the immediately enclosing class
documentation: |-
#### Description
The analyzer produces this diagnostic when an initializing formal
parameter is found in a constructor in a class that doesn't declare the
field being initialized. Constructors can't initialize fields that aren't
declared and fields that are inherited from superclasses.
#### Example
The following code produces this diagnostic because the field `x` isn't
defined:
```dart
%language=2.9
class C {
int y;
C([!this.x!]);
}
```
#### Common fixes
If the field name was wrong, then change it to the name of an existing
field:
```dart
%language=2.9
class C {
int y;
C(this.y);
}
```
If the field name is correct but hasn't yet been defined, then declare the
field:
```dart
%language=2.9
class C {
int x;
int y;
C(this.x);
}
```
If the parameter is needed but shouldn't initialize a field, then convert
it to a normal parameter and use it:
```dart
%language=2.9
class C {
int y;
C(int x) : y = x * 2;
}
```
If the parameter isn't needed, then remove it:
```dart
%language=2.9
class C {
int y;
C();
}
```
INSTANCE_ACCESS_TO_STATIC_MEMBER:
problemMessage: "The static {1} '{0}' can't be accessed through an instance."
correctionMessage: "Try using the {3} '{2}' to access the {1}."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the static member
1: the kind of the static member (field, getter, setter, or method)
2: the name of the static member's enclosing element
3: the kind of the static member's enclosing element (class, mixin, or extension)
documentation: |-
#### Description
The analyzer produces this diagnostic when an access operator is used to
access a static member through an instance of the class.
#### Example
The following code produces this diagnostic because `zero` is a static
field, but it's being accessed as if it were an instance field:
```dart
void f(C c) {
c.[!zero!];
}
class C {
static int zero = 0;
}
```
#### Common fixes
Use the class to access the static member:
```dart
void f(C c) {
C.zero;
}
class C {
static int zero = 0;
}
```
INSTANCE_ACCESS_TO_STATIC_MEMBER_OF_UNNAMED_EXTENSION:
sharedName: INSTANCE_ACCESS_TO_STATIC_MEMBER
problemMessage: "The static {1} '{0}' can't be accessed through an instance."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the static member
1: the kind of the static member (field, getter, setter, or method)
INSTANCE_MEMBER_ACCESS_FROM_FACTORY:
problemMessage: "Instance members can't be accessed from a factory constructor."
correctionMessage: Try removing the reference to the instance member.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a factory constructor contains
an unqualified reference to an instance member. In a generative
constructor, the instance of the class is created and initialized before
the body of the constructor is executed, so the instance can be bound to
`this` and accessed just like it would be in an instance method. But, in a
factory constructor, the instance isn't created before executing the body,
so `this` can't be used to reference it.
#### Example
The following code produces this diagnostic because `x` isn't in scope in
the factory constructor:
```dart
class C {
int x;
factory C() {
return C._([!x!]);
}
C._(this.x);
}
```
#### Common fixes
Rewrite the code so that it doesn't reference the instance member:
```dart
class C {
int x;
factory C() {
return C._(0);
}
C._(this.x);
}
```
INSTANCE_MEMBER_ACCESS_FROM_STATIC:
problemMessage: "Instance members can't be accessed from a static method."
correctionMessage: "Try removing the reference to the instance member, or removing the keyword 'static' from the method."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a static method contains an
unqualified reference to an instance member.
#### Example
The following code produces this diagnostic because the instance field `x`
is being referenced in a static method:
```dart
%language=2.9
class C {
int x;
static int m() {
return [!x!];
}
}
```
#### Common fixes
If the method must reference the instance member, then it can't be static,
so remove the keyword:
```dart
%language=2.9
class C {
int x;
int m() {
return x;
}
}
```
If the method can't be made an instance method, then add a parameter so
that an instance of the class can be passed in:
```dart
%language=2.9
class C {
int x;
static int m(C c) {
return c.x;
}
}
```
INSTANTIATE_ABSTRACT_CLASS:
problemMessage: "Abstract classes can't be instantiated."
correctionMessage: Try creating an instance of a concrete subtype.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when it finds a constructor
invocation and the constructor is declared in an abstract class. Even
though you can't create an instance of an abstract class, abstract classes
can declare constructors that can be invoked by subclasses.
#### Example
The following code produces this diagnostic because `C` is an abstract
class:
```dart
abstract class C {}
var c = new [!C!]();
```
#### Common fixes
If there's a concrete subclass of the abstract class that can be used, then
create an instance of the concrete subclass.
INSTANTIATE_ENUM:
problemMessage: "Enums can't be instantiated."
correctionMessage: Try using one of the defined constants.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when an enum is instantiated. It's
invalid to create an instance of an enum by invoking a constructor; only
the instances named in the declaration of the enum can exist.
#### Example
The following code produces this diagnostic because the enum `E` is being
instantiated:
```dart
// @dart = 2.16
enum E {a}
var e = [!E!]();
```
#### Common fixes
If you intend to use an instance of the enum, then reference one of the
constants defined in the enum:
```dart
// @dart = 2.16
enum E {a}
var e = E.a;
```
If you intend to use an instance of a class, then use the name of that class in place of the name of the enum.
INSTANTIATE_TYPE_ALIAS_EXPANDS_TO_TYPE_PARAMETER:
problemMessage: "Type aliases that expand to a type parameter can't be instantiated."
correctionMessage: Try replacing it with a class.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a constructor invocation is
found where the type being instantiated is a type alias for one of the type
parameters of the type alias. This isn't allowed because the value of the
type parameter is a type rather than a class.
#### Example
The following code produces this diagnostic because it creates an instance
of `A`, even though `A` is a type alias that is defined to be equivalent to
a type parameter:
```dart
typedef A<T> = T;
void f() {
const [!A!]<int>();
}
```
#### Common fixes
Use either a class name or a type alias defined to be a class, rather than
a type alias defined to be a type parameter:
```dart
typedef A<T> = C<T>;
void f() {
const A<int>();
}
class C<T> {
const C();
}
```
INTEGER_LITERAL_IMPRECISE_AS_DOUBLE:
problemMessage: "The integer literal is being used as a double, but can't be represented as a 64-bit double without overflow or loss of precision: '{0}'."
correctionMessage: "Try using the class 'BigInt', or switch to the closest valid double: '{1}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the lexeme of the integer
1: the closest valid double
documentation: |-
#### Description
The analyzer produces this diagnostic when an integer literal is being
implicitly converted to a double, but can't be represented as a 64-bit
double without overflow or loss of precision. Integer literals are
implicitly converted to a double if the context requires the type `double`.
#### Example
The following code produces this diagnostic because the integer value
`9223372036854775807` can't be represented exactly as a double:
```dart
double x = [!9223372036854775807!];
```
#### Common fixes
If you need to use the exact value, then use the class `BigInt` to
represent the value:
```dart
var x = BigInt.parse('9223372036854775807');
```
If you need to use a double, then change the value to one that can be
represented exactly:
```dart
double x = 9223372036854775808;
```
INTEGER_LITERAL_OUT_OF_RANGE:
problemMessage: "The integer literal {0} can't be represented in 64 bits."
correctionMessage: "Try using the 'BigInt' class if you need an integer larger than 9,223,372,036,854,775,807 or less than -9,223,372,036,854,775,808."
hasPublishedDocs: true
comment: |-
Parameters:
0: the value of the literal
documentation: |-
#### Description
The analyzer produces this diagnostic when an integer literal has a value
that is too large (positive) or too small (negative) to be represented in a
64-bit word.
#### Example
The following code produces this diagnostic because the value can't be
represented in 64 bits:
```dart
var x = [!9223372036854775810!];
```
#### Common fixes
If you need to represent the current value, then wrap it in an instance of
the class `BigInt`:
```dart
var x = BigInt.parse('9223372036854775810');
```
INTERFACE_CLASS_EXTENDED_OUTSIDE_OF_LIBRARY:
sharedName: INVALID_USE_OF_TYPE_OUTSIDE_LIBRARY
problemMessage: "The class '{0}' can't be extended outside of its library because it's an interface class."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the interface class being extended.
INVALID_ANNOTATION:
problemMessage: Annotation must be either a const variable reference or const constructor invocation.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when an annotation is found that is
using something that is neither a variable marked as `const` or the
invocation of a `const` constructor.
Getters can't be used as annotations.
#### Examples
The following code produces this diagnostic because the variable `v` isn't
a `const` variable:
```dart
var v = 0;
[!@v!]
void f() {
}
```
The following code produces this diagnostic because `f` isn't a variable:
```dart
[!@f!]
void f() {
}
```
The following code produces this diagnostic because `f` isn't a
constructor:
```dart
[!@f()!]
void f() {
}
```
The following code produces this diagnostic because `g` is a getter:
```dart
[!@g!]
int get g => 0;
```
#### Common fixes
If the annotation is referencing a variable that isn't a `const`
constructor, add the keyword `const` to the variable's declaration:
```dart
const v = 0;
@v
void f() {
}
```
If the annotation isn't referencing a variable, then remove it:
```dart
int v = 0;
void f() {
}
```
INVALID_ANNOTATION_CONSTANT_VALUE_FROM_DEFERRED_LIBRARY:
problemMessage: "Constant values from a deferred library can't be used in annotations."
correctionMessage: "Try moving the constant from the deferred library, or removing 'deferred' from the import."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a constant defined in a library
that is imported as a deferred library is referenced in the argument list
of an annotation. Annotations are evaluated at compile time, and values
from deferred libraries aren't available at compile time.
For more information, check out
[Lazily loading a library](https://dart.dev/language/libraries#lazily-loading-a-library).
#### Example
The following code produces this diagnostic because the constant `pi` is
being referenced in the argument list of an annotation, even though the
library that defines it is being imported as a deferred library:
```dart
import 'dart:math' deferred as math;
class C {
const C(double d);
}
@C(math.[!pi!])
void f () {}
```
#### Common fixes
If you need to reference the imported constant, then remove the `deferred`
keyword:
```dart
import 'dart:math' as math;
class C {
const C(double d);
}
@C(math.pi)
void f () {}
```
If the import is required to be deferred and there's another constant that
is appropriate, then use that constant in place of the constant from the
deferred library.
INVALID_ANNOTATION_FROM_DEFERRED_LIBRARY:
problemMessage: "Constant values from a deferred library can't be used as annotations."
correctionMessage: Try removing the annotation, or changing the import to not be deferred.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a constant from a library that
is imported using a deferred import is used as an annotation. Annotations
are evaluated at compile time, and constants from deferred libraries aren't
available at compile time.
For more information, check out
[Lazily loading a library](https://dart.dev/language/libraries#lazily-loading-a-library).
#### Example
The following code produces this diagnostic because the constant `pi` is
being used as an annotation when the library `dart:math` is imported as
`deferred`:
```dart
import 'dart:math' deferred as math;
@[!math.pi!]
void f() {}
```
#### Common fixes
If you need to reference the constant as an annotation, then remove the
keyword `deferred` from the import:
```dart
import 'dart:math' as math;
@math.pi
void f() {}
```
If you can use a different constant as an annotation, then replace the
annotation with a different constant:
```dart
@deprecated
void f() {}
```
INVALID_ASSIGNMENT:
problemMessage: "A value of type '{0}' can't be assigned to a variable of type '{1}'."
correctionMessage: "Try changing the type of the variable, or casting the right-hand type to '{1}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the right hand side type
1: the name of the left hand side type
documentation: |-
#### Description
The analyzer produces this diagnostic when the static type of an expression
that is assigned to a variable isn't assignable to the type of the
variable.
#### Example
The following code produces this diagnostic because the type of the
initializer (`int`) isn't assignable to the type of the variable
(`String`):
```dart
int i = 0;
String s = [!i!];
```
#### Common fixes
If the value being assigned is always assignable at runtime, even though
the static types don't reflect that, then add an explicit cast.
Otherwise, change the value being assigned so that it has the expected
type. In the previous example, this might look like:
```dart
int i = 0;
String s = i.toString();
```
If you can't change the value, then change the type of the variable to be
compatible with the type of the value being assigned:
```dart
int i = 0;
int s = i;
```
INVALID_CAST_FUNCTION:
problemMessage: "The function '{0}' has type '{1}' that isn't of expected type '{2}'. This means its parameter or return type doesn't match what is expected."
comment: |-
Parameters:
0: the name of the function
1: the type of the function
2: the expected function type
This error is only reported in libraries which are not null safe.
INVALID_CAST_FUNCTION_EXPR:
problemMessage: The function expression type '{0}' isn't of type '{1}'. This means its parameter or return type doesn't match what is expected. Consider changing parameter type(s) or the returned type(s).
comment: |-
Parameters:
0: the type of the torn-off function expression
1: the expected function type
This error is only reported in libraries which are not null safe.
INVALID_CAST_LITERAL:
problemMessage: "The literal '{0}' with type '{1}' isn't of expected type '{2}'."
comment: |-
Parameters:
0: the lexeme of the literal
1: the type of the literal
2: the expected type
This error is only reported in libraries which are not null safe.
INVALID_CAST_LITERAL_LIST:
problemMessage: "The list literal type '{0}' isn't of expected type '{1}'. The list's type can be changed with an explicit generic type argument or by changing the element types."
comment: |-
Parameters:
0: the type of the list literal
1: the expected type
This error is only reported in libraries which are not null safe.
INVALID_CAST_LITERAL_MAP:
problemMessage: "The map literal type '{0}' isn't of expected type '{1}'. The map's type can be changed with an explicit generic type arguments or by changing the key and value types."
comment: |-
Parameters:
0: the type of the map literal
1: the expected type
This error is only reported in libraries which are not null safe.
INVALID_CAST_LITERAL_SET:
problemMessage: "The set literal type '{0}' isn't of expected type '{1}'. The set's type can be changed with an explicit generic type argument or by changing the element types."
comment: |-
Parameters:
0: the type of the set literal
1: the expected type
This error is only reported in libraries which are not null safe.
INVALID_CAST_METHOD:
problemMessage: "The method tear-off '{0}' has type '{1}' that isn't of expected type '{2}'. This means its parameter or return type doesn't match what is expected."
comment: |-
Parameters:
0: the name of the torn-off method
1: the type of the torn-off method
2: the expected function type
This error is only reported in libraries which are not null safe.
INVALID_CAST_NEW_EXPR:
problemMessage: "The constructor returns type '{0}' that isn't of expected type '{1}'."
comment: |-
Parameters:
0: the type of the instantiated object
1: the expected type
This error is only reported in libraries which are not null safe.
INVALID_CONSTANT:
problemMessage: Invalid constant value.
comment: |-
TODO(brianwilkerson) Remove this when we have decided on how to report
errors in compile-time constants. Until then, this acts as a placeholder
for more informative errors.
See TODOs in ConstantVisitor
INVALID_EXTENSION_ARGUMENT_COUNT:
problemMessage: "Extension overrides must have exactly one argument: the value of 'this' in the extension method."
correctionMessage: Try specifying exactly one argument.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when an extension override doesn't
have exactly one argument. The argument is the expression used to compute
the value of `this` within the extension method, so there must be one
argument.
#### Examples
The following code produces this diagnostic because there are no arguments:
```dart
extension E on String {
String join(String other) => '$this $other';
}
void f() {
E[!()!].join('b');
}
```
And, the following code produces this diagnostic because there's more than
one argument:
```dart
extension E on String {
String join(String other) => '$this $other';
}
void f() {
E[!('a', 'b')!].join('c');
}
```
#### Common fixes
Provide one argument for the extension override:
```dart
extension E on String {
String join(String other) => '$this $other';
}
void f() {
E('a').join('b');
}
```
INVALID_FACTORY_NAME_NOT_A_CLASS:
problemMessage: The name of a factory constructor must be the same as the name of the immediately enclosing class.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the name of a factory
constructor isn't the same as the name of the surrounding class.
#### Example
The following code produces this diagnostic because the name of the factory
constructor (`A`) isn't the same as the surrounding class (`C`):
```dart
class A {}
class C {
factory [!A!]() => throw 0;
}
```
#### Common fixes
If the factory returns an instance of the surrounding class, and you
intend it to be an unnamed factory constructor, then rename the factory:
```dart
class A {}
class C {
factory C() => throw 0;
}
```
If the factory returns an instance of the surrounding class, and you
intend it to be a named factory constructor, then prefix the name of the
factory constructor with the name of the surrounding class:
```dart
class A {}
class C {
factory C.a() => throw 0;
}
```
If the factory returns an instance of a different class, then move the
factory to that class:
```dart
class A {
factory A() => throw 0;
}
class C {}
```
If the factory returns an instance of a different class, but you can't
modify that class or don't want to move the factory, then convert it to be
a static method:
```dart
class A {}
class C {
static A a() => throw 0;
}
```
INVALID_FIELD_NAME_FROM_OBJECT:
sharedName: INVALID_FIELD_NAME
problemMessage: Record field names can't be the same as a member from 'Object'.
correctionMessage: Try using a different name for the field.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when either a record literal or a
record type annotation has a field whose name is invalid. The name is
invalid if it is:
- private (starts with `_`)
- the same as one of the members defined on `Object`
- the same as the name of a positional field (an exception is made if the
field is a positional field with the specified name)
#### Examples
The following code produces this diagnostic because the record literal has
a field named `toString`, which is a method defined on `Object`:
```dart
var r = (a: 1, [!toString!]: 4);
```
The following code produces this diagnostic because the record type
annotation has a field named `hashCode`, which is a getter defined on
`Object`:
```dart
void f(({int a, int [!hashCode!]}) r) {}
```
The following code produces this diagnostic because the record literal has
a private field named `_a`:
```dart
var r = ([!_a!]: 1, b: 2);
```
The following code produces this diagnostic because the record type
annotation has a private field named `_a`:
```dart
void f(({int [!_a!], int b}) r) {}
```
The following code produces this diagnostic because the record literal has
a field named `$1`, which is also the name of a different positional
parameter:
```dart
var r = (2, [!$1!]: 1);
```
The following code produces this diagnostic because the record type
annotation has a field named `$1`, which is also the name of a different
positional parameter:
```dart
void f((int, String, {int [!$1!]}) r) {}
```
#### Common fixes
Rename the field:
```dart
var r = (a: 1, d: 4);
```
INVALID_FIELD_NAME_PRIVATE:
sharedName: INVALID_FIELD_NAME
problemMessage: Record field names can't be private.
correctionMessage: Try removing the leading underscore.
hasPublishedDocs: true
comment: No parameters.
INVALID_FIELD_NAME_POSITIONAL:
sharedName: INVALID_FIELD_NAME
problemMessage: Record field names can't be a dollar sign followed by an integer when the integer is the index of a positional field.
correctionMessage: Try using a different name for the field.
hasPublishedDocs: true
comment: No parameters.
INVALID_IMPLEMENTATION_OVERRIDE:
problemMessage: "'{1}.{0}' ('{2}') isn't a valid concrete implementation of '{3}.{0}' ('{4}')."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the declared member that is not a valid override.
1: the name of the interface that declares the member.
2: the type of the declared member in the interface.
3: the name of the interface with the overridden member.
4: the type of the overridden member.
These parameters must be kept in sync with those of
[CompileTimeErrorCode.INVALID_OVERRIDE].
documentation: |-
#### Description
The analyzer produces this diagnostic when all of the following are true:
- A class defines an abstract member.
- There is a concrete implementation of that member in a superclass.
- The concrete implementation isn't a valid implementation of the abstract
method.
The concrete implementation can be invalid because of incompatibilities in
either the return type, the types of parameters, or the type variables.
#### Example
The following code produces this diagnostic because the method `A.add` has
a parameter of type `int`, and the overriding method `B.add` has a
corresponding parameter of type `num`:
```dart
class A {
int add(int a) => a;
}
class [!B!] extends A {
int add(num a);
}
```
This is a problem because in an invocation of `B.add` like the following:
```dart
void f(B b) {
b.add(3.4);
}
```
`B.add` is expecting to be able to take, for example, a `double`, but when
the method `A.add` is executed (because it's the only concrete
implementation of `add`), a runtime exception will be thrown because a
`double` can't be assigned to a parameter of type `int`.
#### Common fixes
If the method in the subclass can conform to the implementation in the
superclass, then change the declaration in the subclass (or remove it if
it's the same):
```dart
class A {
int add(int a) => a;
}
class B extends A {
int add(int a);
}
```
If the method in the superclass can be generalized to be a valid
implementation of the method in the subclass, then change the superclass
method:
```dart
class A {
int add(num a) => a.floor();
}
class B extends A {
int add(num a);
}
```
If neither the method in the superclass nor the method in the subclass can
be changed, then provide a concrete implementation of the method in the
subclass:
```dart
class A {
int add(int a) => a;
}
class B extends A {
int add(num a) => a.floor();
}
```
INVALID_IMPLEMENTATION_OVERRIDE_SETTER:
sharedName: INVALID_IMPLEMENTATION_OVERRIDE
problemMessage: "The setter '{1}.{0}' ('{2}') isn't a valid concrete implementation of '{3}.{0}' ('{4}')."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the declared setter that is not a valid override.
1: the name of the interface that declares the setter.
2: the type of the declared setter in the interface.
3: the name of the interface with the overridden setter.
4: the type of the overridden setter.
These parameters must be kept in sync with those of
[CompileTimeErrorCode.INVALID_OVERRIDE].
INVALID_INLINE_FUNCTION_TYPE:
problemMessage: "Inline function types can't be used for parameters in a generic function type."
correctionMessage: "Try using a generic function type (returnType 'Function(' parameters ')')."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a generic function type has a
function-valued parameter that is written using the older inline function
type syntax.
#### Example
The following code produces this diagnostic because the parameter `f`, in
the generic function type used to define `F`, uses the inline function
type syntax:
```dart
typedef F = int Function(int f[!(!]String s));
```
#### Common fixes
Use the generic function syntax for the parameter's type:
```dart
typedef F = int Function(int Function(String));
```
INVALID_MODIFIER_ON_CONSTRUCTOR:
problemMessage: "The modifier '{0}' can't be applied to the body of a constructor."
correctionMessage: Try removing the modifier.
hasPublishedDocs: true
comment: |-
Parameters:
0: the invalid modifier
documentation: |-
#### Description
The analyzer produces this diagnostic when the body of a constructor is
prefixed by one of the following modifiers: `async`, `async*`, or `sync*`.
Constructor bodies must be synchronous.
#### Example
The following code produces this diagnostic because the body of the
constructor for `C` is marked as being `async`:
```dart
class C {
C() [!async!] {}
}
```
#### Common fixes
If the constructor can be synchronous, then remove the modifier:
```dart
class C {
C();
}
```
If the constructor can't be synchronous, then use a static method to create
the instance instead:
```dart
class C {
C();
static Future<C> c() async {
return C();
}
}
```
INVALID_MODIFIER_ON_SETTER:
problemMessage: "Setters can't use 'async', 'async*', or 'sync*'."
correctionMessage: Try removing the modifier.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the body of a setter is prefixed
by one of the following modifiers: `async`, `async*`, or `sync*`. Setter
bodies must be synchronous.
#### Example
The following code produces this diagnostic because the body of the setter
`x` is marked as being `async`:
```dart
class C {
set x(int i) [!async!] {}
}
```
#### Common fixes
If the setter can be synchronous, then remove the modifier:
```dart
class C {
set x(int i) {}
}
```
If the setter can't be synchronous, then use a method to set the value
instead:
```dart
class C {
void x(int i) async {}
}
```
INVALID_OVERRIDE:
problemMessage: "'{1}.{0}' ('{2}') isn't a valid override of '{3}.{0}' ('{4}')."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the declared member that is not a valid override.
1: the name of the interface that declares the member.
2: the type of the declared member in the interface.
3: the name of the interface with the overridden member.
4: the type of the overridden member.
documentation: |-
#### Description
The analyzer produces this diagnostic when a member of a class is found
that overrides a member from a supertype and the override isn't valid. An
override is valid if all of these are true:
* It allows all of the arguments allowed by the overridden member.
* It doesn't require any arguments that aren't required by the overridden
member.
* The type of every parameter of the overridden member is assignable to the
corresponding parameter of the override.
* The return type of the override is assignable to the return type of the
overridden member.
#### Example
The following code produces this diagnostic because the type of the
parameter `s` (`String`) isn't assignable to the type of the parameter `i`
(`int`):
```dart
class A {
void m(int i) {}
}
class B extends A {
void [!m!](String s) {}
}
```
#### Common fixes
If the invalid method is intended to override the method from the
superclass, then change it to conform:
```dart
class A {
void m(int i) {}
}
class B extends A {
void m(int i) {}
}
```
If it isn't intended to override the method from the superclass, then
rename it:
```dart
class A {
void m(int i) {}
}
class B extends A {
void m2(String s) {}
}
```
INVALID_OVERRIDE_SETTER:
sharedName: INVALID_OVERRIDE
problemMessage: "The setter '{1}.{0}' ('{2}') isn't a valid override of '{3}.{0}' ('{4}')."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the declared setter that is not a valid override.
1: the name of the interface that declares the setter.
2: the type of the declared setter in the interface.
3: the name of the interface with the overridden setter.
4: the type of the overridden setter.
INVALID_REFERENCE_TO_GENERATIVE_ENUM_CONSTRUCTOR:
problemMessage: Generative enum constructors can only be used as targets of redirection.
correctionMessage: Try using an enum constant, or a factory constructor.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a generative constructor
defined on an enum is used anywhere other than to create one of the enum
constants or as the target of a redirection from another constructor in
the same enum.
#### Example
The following code produces this diagnostic because the constructor for
`E` is being used to create an instance in the function `f`:
```dart
enum E {
a(0);
const E(int x);
}
E f() => const [!E!](2);
```
#### Common fixes
If there's an enum constant with the same value, or if you add such a
constant, then reference the constant directly:
```dart
enum E {
a(0), b(2);
const E(int x);
}
E f() => E.b;
```
If you need to use a constructor invocation, then use a factory
constructor:
```dart
enum E {
a(0);
const E(int x);
factory E.c(int x) => a;
}
E f() => E.c(2);
```
INVALID_REFERENCE_TO_THIS:
problemMessage: "Invalid reference to 'this' expression."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when `this` is used outside of an
instance method or a generative constructor. The reserved word `this` is
only defined in the context of an instance method or a generative
constructor.
#### Example
The following code produces this diagnostic because `v` is a top-level
variable:
```dart
C f() => [!this!];
class C {}
```
#### Common fixes
Use a variable of the appropriate type in place of `this`, declaring it if
necessary:
```dart
C f(C c) => c;
class C {}
```
INVALID_SUPER_FORMAL_PARAMETER_LOCATION:
problemMessage: Super parameters can only be used in non-redirecting generative constructors.
correctionMessage: Try removing the 'super' modifier, or changing the constructor to be non-redirecting and generative.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a super parameter is used
anywhere other than a non-redirecting generative constructor.
#### Examples
The following code produces this diagnostic because the super parameter
`x` is in a redirecting generative constructor:
```dart
class A {
A(int x);
}
class B extends A {
B.b([!super!].x) : this._();
B._() : super(0);
}
```
The following code produces this diagnostic because the super parameter
`x` isn't in a generative constructor:
```dart
class A {
A(int x);
}
class C extends A {
factory C.c([!super!].x) => C._();
C._() : super(0);
}
```
The following code produces this diagnostic because the super parameter
`x` is in a method:
```dart
class A {
A(int x);
}
class D extends A {
D() : super(0);
void m([!super!].x) {}
}
```
#### Common fixes
If the function containing the super parameter can be changed to be a
non-redirecting generative constructor, then do so:
```dart
class A {
A(int x);
}
class B extends A {
B.b(super.x);
}
```
If the function containing the super parameter can't be changed to be a
non-redirecting generative constructor, then remove the `super`:
```dart
class A {
A(int x);
}
class D extends A {
D() : super(0);
void m(int x) {}
}
```
INVALID_TYPE_ARGUMENT_IN_CONST_LIST:
sharedName: INVALID_TYPE_ARGUMENT_IN_CONST_LITERAL
problemMessage: "Constant list literals can't include a type parameter as a type argument, such as '{0}'."
correctionMessage: Try replacing the type parameter with a different type.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the type parameter
documentation: |-
#### Description
The analyzer produces this diagnostic when a type parameter is used as a
type argument in a list, map, or set literal that is prefixed by `const`.
This isn't allowed because the value of the type parameter (the actual type
that will be used at runtime) can't be known at compile time.
#### Examples
The following code produces this diagnostic because the type parameter `T`
is being used as a type argument when creating a constant list:
```dart
List<T> newList<T>() => const <[!T!]>[];
```
The following code produces this diagnostic because the type parameter `T`
is being used as a type argument when creating a constant map:
```dart
Map<String, T> newSet<T>() => const <String, [!T!]>{};
```
The following code produces this diagnostic because the type parameter `T`
is being used as a type argument when creating a constant set:
```dart
Set<T> newSet<T>() => const <[!T!]>{};
```
#### Common fixes
If the type that will be used for the type parameter can be known at
compile time, then remove the type parameter:
```dart
List<int> newList() => const <int>[];
```
If the type that will be used for the type parameter can't be known until
runtime, then remove the keyword `const`:
```dart
List<T> newList<T>() => <T>[];
```
INVALID_TYPE_ARGUMENT_IN_CONST_MAP:
sharedName: INVALID_TYPE_ARGUMENT_IN_CONST_LITERAL
problemMessage: "Constant map literals can't include a type parameter as a type argument, such as '{0}'."
correctionMessage: Try replacing the type parameter with a different type.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the type parameter
INVALID_TYPE_ARGUMENT_IN_CONST_SET:
sharedName: INVALID_TYPE_ARGUMENT_IN_CONST_LITERAL
problemMessage: "Constant set literals can't include a type parameter as a type argument, such as '{0}'."
correctionMessage: Try replacing the type parameter with a different type.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the type parameter
INVALID_URI:
problemMessage: "Invalid URI syntax: '{0}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the URI that is invalid
documentation: |-
#### Description
The analyzer produces this diagnostic when a URI in a directive doesn't
conform to the syntax of a valid URI.
#### Example
The following code produces this diagnostic because `'#'` isn't a valid
URI:
```dart
import [!'#'!];
```
#### Common fixes
Replace the invalid URI with a valid URI.
INVALID_USE_OF_COVARIANT:
problemMessage: "The 'covariant' keyword can only be used for parameters in instance methods or before non-final instance fields."
correctionMessage: "Try removing the 'covariant' keyword."
comment: "The 'covariant' keyword was found in an inappropriate location."
INVALID_USE_OF_NULL_VALUE:
problemMessage: "An expression whose value is always 'null' can't be dereferenced."
correctionMessage: Try changing the type of the expression.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when an expression whose value will
always be `null` is dereferenced.
#### Example
The following code produces this diagnostic because `x` will always be
`null`:
```dart
int f(Null x) {
return [!x!].length;
}
```
#### Common fixes
If the value is allowed to be something other than `null`, then change the
type of the expression:
```dart
int f(String? x) {
return x!.length;
}
```
INVOCATION_OF_EXTENSION_WITHOUT_CALL:
problemMessage: "The extension '{0}' doesn't define a 'call' method so the override can't be used in an invocation."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the extension
documentation: |-
#### Description
The analyzer produces this diagnostic when an extension override is used to
invoke a function but the extension doesn't declare a `call` method.
#### Example
The following code produces this diagnostic because the extension `E`
doesn't define a `call` method:
```dart
extension E on String {}
void f() {
[!E('')!]();
}
```
#### Common fixes
If the extension is intended to define a `call` method, then declare it:
```dart
extension E on String {
int call() => 0;
}
void f() {
E('')();
}
```
If the extended type defines a `call` method, then remove the extension
override.
If the `call` method isn't defined, then rewrite the code so that it
doesn't invoke the `call` method.
INVOCATION_OF_NON_FUNCTION:
problemMessage: "'{0}' isn't a function."
correctionMessage: "Try correcting the name to match an existing function, or define a method or function named '{0}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the identifier that is not a function type
documentation: |-
#### Description
The analyzer produces this diagnostic when it finds a function invocation,
but the name of the function being invoked is defined to be something other
than a function.
#### Example
The following code produces this diagnostic because `Binary` is the name of
a function type, not a function:
```dart
typedef Binary = int Function(int, int);
int f() {
return [!Binary!](1, 2);
}
```
#### Common fixes
Replace the name with the name of a function.
INVOCATION_OF_NON_FUNCTION_EXPRESSION:
problemMessage: "The expression doesn't evaluate to a function, so it can't be invoked."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a function invocation is found,
but the name being referenced isn't the name of a function, or when the
expression computing the function doesn't compute a function.
#### Examples
The following code produces this diagnostic because `x` isn't a function:
```dart
int x = 0;
int f() => x;
var y = [!x!]();
```
The following code produces this diagnostic because `f()` doesn't return a
function:
```dart
int x = 0;
int f() => x;
var y = [!f()!]();
```
#### Common fixes
If you need to invoke a function, then replace the code before the argument
list with the name of a function or with an expression that computes a
function:
```dart
int x = 0;
int f() => x;
var y = f();
```
LABEL_IN_OUTER_SCOPE:
problemMessage: "Can't reference label '{0}' declared in an outer method."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the unresolvable label
documentation: |-
#### Description
The analyzer produces this diagnostic when a `break` or `continue`
statement references a label that is declared in a method or function
containing the function in which the `break` or `continue` statement
appears. The `break` and `continue` statements can't be used to transfer
control outside the function that contains them.
#### Example
The following code produces this diagnostic because the label `loop` is
declared outside the local function `g`:
```dart
void f() {
loop:
while (true) {
void g() {
break [!loop!];
}
g();
}
}
```
#### Common fixes
Try rewriting the code so that it isn't necessary to transfer control
outside the local function, possibly by inlining the local function:
```dart
void f() {
loop:
while (true) {
break loop;
}
}
```
If that isn't possible, then try rewriting the local function so that a
value returned by the function can be used to determine whether control is
transferred:
```dart
void f() {
loop:
while (true) {
bool g() {
return true;
}
if (g()) {
break loop;
}
}
}
```
LABEL_UNDEFINED:
problemMessage: "Can't reference an undefined label '{0}'."
correctionMessage: Try defining the label, or correcting the name to match an existing label.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the unresolvable label
documentation: |-
#### Description
The analyzer produces this diagnostic when it finds a reference to a label
that isn't defined in the scope of the `break` or `continue` statement that
is referencing it.
#### Example
The following code produces this diagnostic because the label `loop` isn't
defined anywhere:
```dart
void f() {
for (int i = 0; i < 10; i++) {
for (int j = 0; j < 10; j++) {
if (j != 0) {
break [!loop!];
}
}
}
}
```
#### Common fixes
If the label should be on the innermost enclosing `do`, `for`, `switch`, or
`while` statement, then remove the label:
```dart
void f() {
for (int i = 0; i < 10; i++) {
for (int j = 0; j < 10; j++) {
if (j != 0) {
break;
}
}
}
}
```
If the label should be on some other statement, then add the label:
```dart
void f() {
loop: for (int i = 0; i < 10; i++) {
for (int j = 0; j < 10; j++) {
if (j != 0) {
break loop;
}
}
}
}
```
LATE_FINAL_FIELD_WITH_CONST_CONSTRUCTOR:
problemMessage: "Can't have a late final field in a class with a generative const constructor."
correctionMessage: "Try removing the 'late' modifier, or don't declare 'const' constructors."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a class that has at least one
`const` constructor also has a field marked both `late` and `final`.
#### Example
The following code produces this diagnostic because the class `A` has a
`const` constructor and the `final` field `f` is marked as `late`:
```dart
class A {
[!late!] final int f;
const A();
}
```
#### Common fixes
If the field doesn't need to be marked `late`, then remove the `late`
modifier from the field:
```dart
class A {
final int f = 0;
const A();
}
```
If the field must be marked `late`, then remove the `const` modifier from
the constructors:
```dart
class A {
late final int f;
A();
}
```
LATE_FINAL_LOCAL_ALREADY_ASSIGNED:
problemMessage: The late final local variable is already assigned.
correctionMessage: "Try removing the 'final' modifier, or don't reassign the value."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the analyzer can prove that a
local variable marked as both `late` and `final` was already assigned a
value at the point where another assignment occurs.
Because `final` variables can only be assigned once, subsequent assignments
are guaranteed to fail, so they're flagged.
#### Example
The following code produces this diagnostic because the `final` variable
`v` is assigned a value in two places:
```dart
int f() {
late final int v;
v = 0;
[!v!] += 1;
return v;
}
```
#### Common fixes
If you need to be able to reassign the variable, then remove the `final`
keyword:
```dart
int f() {
late int v;
v = 0;
v += 1;
return v;
}
```
If you don't need to reassign the variable, then remove all except the
first of the assignments:
```dart
int f() {
late final int v;
v = 0;
return v;
}
```
LIST_ELEMENT_TYPE_NOT_ASSIGNABLE:
problemMessage: "The element type '{0}' can't be assigned to the list type '{1}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the actual type of the list element
1: the expected type of the list element
documentation: |-
#### Description
The analyzer produces this diagnostic when the type of an element in a list
literal isn't assignable to the element type of the list.
#### Example
The following code produces this diagnostic because `2.5` is a double, and
the list can hold only integers:
```dart
List<int> x = [1, [!2.5!], 3];
```
#### Common fixes
If you intended to add a different object to the list, then replace the
element with an expression that computes the intended object:
```dart
List<int> x = [1, 2, 3];
```
If the object shouldn't be in the list, then remove the element:
```dart
List<int> x = [1, 3];
```
If the object being computed is correct, then widen the element type of the
list to allow all of the different types of objects it needs to contain:
```dart
List<num> x = [1, 2.5, 3];
```
MACRO_EXECUTION_EXCEPTION:
problemMessage: "Exception during macro execution: {0}\n{1}"
correctionMessage: Re-install the Dart or Flutter SDK.
comment: |-
Parameters:
0: the message of the exception
1: the stack trace
MAIN_FIRST_POSITIONAL_PARAMETER_TYPE:
problemMessage: "The type of the first positional parameter of the 'main' function must be a supertype of 'List<String>'."
correctionMessage: Try changing the type of the parameter.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the first positional parameter
of a function named `main` isn't a supertype of `List<String>`.
#### Example
The following code produces this diagnostic because `List<int>` isn't a
supertype of `List<String>`:
```dart
void main([!List<int>!] args) {}
```
#### Common fixes
If the function is an entry point, then change the type of the first
positional parameter to be a supertype of `List<String>`:
```dart
void main(List<String> args) {}
```
If the function isn't an entry point, then change the name of the function:
```dart
void f(List<int> args) {}
```
MAIN_HAS_REQUIRED_NAMED_PARAMETERS:
problemMessage: "The function 'main' can't have any required named parameters."
correctionMessage: "Try using a different name for the function, or removing the 'required' modifier."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a function named `main` has one
or more required named parameters.
#### Example
The following code produces this diagnostic because the function named
`main` has a required named parameter (`x`):
```dart
void [!main!]({required int x}) {}
```
#### Common fixes
If the function is an entry point, then remove the `required` keyword:
```dart
void main({int? x}) {}
```
If the function isn't an entry point, then change the name of the function:
```dart
void f({required int x}) {}
```
MAIN_HAS_TOO_MANY_REQUIRED_POSITIONAL_PARAMETERS:
problemMessage: "The function 'main' can't have more than two required positional parameters."
correctionMessage: Try using a different name for the function, or removing extra parameters.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a function named `main` has more
than two required positional parameters.
#### Example
The following code produces this diagnostic because the function `main` has
three required positional parameters:
```dart
void [!main!](List<String> args, int x, int y) {}
```
#### Common fixes
If the function is an entry point and the extra parameters aren't used,
then remove them:
```dart
void main(List<String> args, int x) {}
```
If the function is an entry point, but the extra parameters used are for
when the function isn't being used as an entry point, then make the extra
parameters optional:
```dart
void main(List<String> args, int x, [int y = 0]) {}
```
If the function isn't an entry point, then change the name of the function:
```dart
void f(List<String> args, int x, int y) {}
```
MAIN_IS_NOT_FUNCTION:
problemMessage: "The declaration named 'main' must be a function."
correctionMessage: Try using a different name for this declaration.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a library contains a declaration
of the name `main` that isn't the declaration of a top-level function.
#### Example
The following code produces this diagnostic because the name `main` is
being used to declare a top-level variable:
```dart
var [!main!] = 3;
```
#### Common fixes
Use a different name for the declaration:
```dart
var mainIndex = 3;
```
MAP_ENTRY_NOT_IN_MAP:
problemMessage: Map entries can only be used in a map literal.
correctionMessage: Try converting the collection to a map or removing the map entry.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a map entry (a key/value pair)
is found in a set literal.
#### Example
The following code produces this diagnostic because the literal has a map
entry even though it's a set literal:
```dart
const collection = <String>{[!'a' : 'b'!]};
```
#### Common fixes
If you intended for the collection to be a map, then change the code so
that it is a map. In the previous example, you could do this by adding
another type argument:
```dart
const collection = <String, String>{'a' : 'b'};
```
In other cases, you might need to change the explicit type from `Set` to
`Map`.
If you intended for the collection to be a set, then remove the map entry,
possibly by replacing the colon with a comma if both values should be
included in the set:
```dart
const collection = <String>{'a', 'b'};
```
MAP_KEY_TYPE_NOT_ASSIGNABLE:
problemMessage: "The element type '{0}' can't be assigned to the map key type '{1}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the type of the expression being used as a key
1: the type of keys declared for the map
documentation: |-
#### Description
The analyzer produces this diagnostic when a key of a key-value pair in a
map literal has a type that isn't assignable to the key type of the map.
#### Example
The following code produces this diagnostic because `2` is an `int`, but
the keys of the map are required to be `String`s:
```dart
var m = <String, String>{[!2!] : 'a'};
```
#### Common fixes
If the type of the map is correct, then change the key to have the correct
type:
```dart
var m = <String, String>{'2' : 'a'};
```
If the type of the key is correct, then change the key type of the map:
```dart
var m = <int, String>{2 : 'a'};
```
MAP_VALUE_TYPE_NOT_ASSIGNABLE:
problemMessage: "The element type '{0}' can't be assigned to the map value type '{1}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the type of the expression being used as a value
1: the type of values declared for the map
documentation: |-
#### Description
The analyzer produces this diagnostic when a value of a key-value pair in a
map literal has a type that isn't assignable to the value type of the
map.
#### Example
The following code produces this diagnostic because `2` is an `int`, but/
the values of the map are required to be `String`s:
```dart
var m = <String, String>{'a' : [!2!]};
```
#### Common fixes
If the type of the map is correct, then change the value to have the
correct type:
```dart
var m = <String, String>{'a' : '2'};
```
If the type of the value is correct, then change the value type of the map:
```dart
var m = <String, int>{'a' : 2};
```
MISSING_CONST_IN_LIST_LITERAL:
problemMessage: Seeing this message constitutes a bug. Please report it.
comment: |-
12.1 Constants: A constant expression is ... a constant list literal.
Note: This diagnostic is never displayed to the user, so it doesn't need
to be documented.
MISSING_CONST_IN_MAP_LITERAL:
problemMessage: Seeing this message constitutes a bug. Please report it.
comment: |-
12.1 Constants: A constant expression is ... a constant map literal.
Note: This diagnostic is never displayed to the user, so it doesn't need
to be documented.
MISSING_CONST_IN_SET_LITERAL:
problemMessage: Seeing this message constitutes a bug. Please report it.
comment: |-
12.1 Constants: A constant expression is ... a constant set literal.
Note: This diagnostic is never displayed to the user, so it doesn't need
to be documented.
MISSING_DART_LIBRARY:
problemMessage: "Required library '{0}' is missing."
correctionMessage: Re-install the Dart or Flutter SDK.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the library
documentation: |-
#### Description
The analyzer produces this diagnostic when either the Dart or Flutter SDK
isn't installed correctly, and, as a result, one of the `dart:` libraries
can't be found.
#### Common fixes
Reinstall the Dart or Flutter SDK.
MISSING_DEFAULT_VALUE_FOR_PARAMETER:
problemMessage: "The parameter '{0}' can't have a value of 'null' because of its type, but the implicit default value is 'null'."
correctionMessage: "Try adding either an explicit non-'null' default value or the 'required' modifier."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the parameter
documentation: |-
#### Description
The analyzer produces this diagnostic when an optional parameter, whether
positional or named, has a [potentially non-nullable][] type and doesn't
specify a default value. Optional parameters that have no explicit default
value have an implicit default value of `null`. If the type of the
parameter doesn't allow the parameter to have a value of `null`, then the
implicit default value isn't valid.
#### Examples
The following code produces this diagnostic because `x` can't be `null`,
and no non-`null` default value is specified:
```dart
void f([int [!x!]]) {}
```
As does this:
```dart
void g({int [!x!]}) {}
```
#### Common fixes
If you want to use `null` to indicate that no value was provided, then you
need to make the type nullable:
```dart
void f([int? x]) {}
void g({int? x}) {}
```
If the parameter can't be null, then either provide a default value:
```dart
void f([int x = 1]) {}
void g({int x = 2}) {}
```
or make the parameter a required parameter:
```dart
void f(int x) {}
void g({required int x}) {}
```
MISSING_DEFAULT_VALUE_FOR_PARAMETER_POSITIONAL:
sharedName: MISSING_DEFAULT_VALUE_FOR_PARAMETER
problemMessage: "The parameter '{0}' can't have a value of 'null' because of its type, but the implicit default value is 'null'."
correctionMessage: "Try adding an explicit non-'null' default value."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the parameter
MISSING_DEFAULT_VALUE_FOR_PARAMETER_WITH_ANNOTATION:
sharedName: MISSING_DEFAULT_VALUE_FOR_PARAMETER
problemMessage: "With null safety, use the 'required' keyword, not the '@required' annotation."
correctionMessage: "Try removing the '@'."
hasPublishedDocs: true
comment: No parameters.
MISSING_NAMED_PATTERN_FIELD_NAME:
problemMessage: The getter name is not specified explicitly, and the pattern is not a variable.
correctionMessage: Try specifying the getter name explicitly, or using a variable pattern.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when, within an object pattern, the
specification of a property and the pattern used to match the property's
value doesn't have either:
- a getter name before the colon
- a variable pattern from which the getter name can be inferred
#### Example
The following code produces this diagnostic because there is no getter
name before the colon and no variable pattern after the colon in the
object pattern (`C(:0)`):
```dart
abstract class C {
int get f;
}
void f(C c) {
switch (c) {
case C([!:0!]):
break;
}
}
```
#### Common fixes
If you need to use the actual value of the property within the pattern's
scope, then add a variable pattern where the name of the variable is the
same as the name of the property being matched:
```dart
abstract class C {
int get f;
}
void f(C c) {
switch (c) {
case C(:var f) when f == 0:
print(f);
}
}
```
If you don't need to use the actual value of the property within the
pattern's scope, then add the name of the property being matched before
the colon:
```dart
abstract class C {
int get f;
}
void f(C c) {
switch (c) {
case C(f: 0):
break;
}
}
```
MISSING_REQUIRED_ARGUMENT:
problemMessage: "The named parameter '{0}' is required, but there's no corresponding argument."
correctionMessage: Try adding the required argument.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the parameter
documentation: |-
#### Description
The analyzer produces this diagnostic when an invocation of a function is
missing a required named parameter.
#### Example
The following code produces this diagnostic because the invocation of `f`
doesn't include a value for the required named parameter `end`:
```dart
void f(int start, {required int end}) {}
void g() {
[!f!](3);
}
```
#### Common fixes
Add a named argument corresponding to the missing required parameter:
```dart
void f(int start, {required int end}) {}
void g() {
f(3, end: 5);
}
```
MISSING_VARIABLE_PATTERN:
problemMessage: "Variable pattern '{0}' is missing in this branch of the logical-or pattern."
correctionMessage: "Try declaring this variable pattern in the branch."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the variable pattern
documentation: |-
#### Description
The analyzer produces this diagnostic when one branch of a logical-or
pattern doesn't declare a variable that is declared on the other branch of
the same pattern.
#### Example
The following code produces this diagnostic because the right-hand side of
the logical-or pattern doesn't declare the variable `a`:
```dart
void f((int, int) r) {
if (r case (var a, 0) || [!(0, _)!]) {
print(a);
}
}
```
#### Common fixes
If the variable needs to be referenced in the controlled statements, then
add a declaration of the variable to every branch of the logical-or
pattern:
```dart
void f((int, int) r) {
if (r case (var a, 0) || (0, var a)) {
print(a);
}
}
```
If the variable doesn't need to be referenced in the controlled
statements, then remove the declaration of the variable from every branch
of the logical-or pattern:
```dart
void f((int, int) r) {
if (r case (_, 0) || (0, _)) {
print('found a zero');
}
}
```
If the variable needs to be referenced if one branch of the pattern
matches but not when the other matches, then break the pattern into two
pieces:
```dart
void f((int, int) r) {
switch (r) {
case (var a, 0):
print(a);
case (0, _):
print('found a zero');
}
}
```
MIXINS_SUPER_CLASS:
sharedName: IMPLEMENTS_SUPER_CLASS
problemMessage: "'{0}' can't be used in both the 'extends' and 'with' clauses."
correctionMessage: Try removing one of the occurrences.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the class that appears in both "extends" and "with" clauses
MIXIN_APPLICATION_CONCRETE_SUPER_INVOKED_MEMBER_TYPE:
problemMessage: "The super-invoked member '{0}' has the type '{1}', and the concrete member in the class has the type '{2}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the super-invoked member
1: the display name of the type of the super-invoked member in the mixin
2: the display name of the type of the concrete member in the class
documentation: |-
#### Description
The analyzer produces this diagnostic when a mixin that invokes a method
using `super` is used in a class where the concrete implementation of that
method has a different signature than the signature defined for that method
by the mixin's `on` type. The reason this is an error is because the
invocation in the mixin might invoke the method in a way that's
incompatible with the method that will actually be executed.
#### Example
The following code produces this diagnostic because the class `C` uses the
mixin `M`, the mixin `M` invokes `foo` using `super`, and the abstract
version of `foo` declared in `I` (the mixin's `on` type) doesn't have the
same signature as the concrete version of `foo` declared in `A`:
```dart
class I {
void foo([int? p]) {}
}
class A {
void foo(int p) {}
}
abstract class B extends A implements I {
@override
void foo([int? p]);
}
mixin M on I {
void bar() {
super.foo(42);
}
}
abstract class C extends B with [!M!] {}
```
#### Common fixes
If the class doesn't need to use the mixin, then remove it from the `with`
clause:
```dart
class I {
void foo([int? p]) {}
}
class A {
void foo(int? p) {}
}
abstract class B extends A implements I {
@override
void foo([int? p]);
}
mixin M on I {
void bar() {
super.foo(42);
}
}
abstract class C extends B {}
```
If the class needs to use the mixin, then ensure that there's a concrete
implementation of the method that conforms to the signature expected by the
mixin:
```dart
class I {
void foo([int? p]) {}
}
class A {
void foo(int? p) {}
}
abstract class B extends A implements I {
@override
void foo([int? p]) {
super.foo(p);
}
}
mixin M on I {
void bar() {
super.foo(42);
}
}
abstract class C extends B with M {}
```
MIXIN_APPLICATION_NOT_IMPLEMENTED_INTERFACE:
problemMessage: "'{0}' can't be mixed onto '{1}' because '{1}' doesn't implement '{2}'."
correctionMessage: "Try extending the class '{0}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the display name of the mixin
1: the display name of the superclass
2: the display name of the type that is not implemented
documentation: |-
#### Description
The analyzer produces this diagnostic when a mixin that has a superclass
constraint is used in a [mixin application][] with a superclass that
doesn't implement the required constraint.
#### Example
The following code produces this diagnostic because the mixin `M` requires
that the class to which it's applied be a subclass of `A`, but `Object`
isn't a subclass of `A`:
```dart
class A {}
mixin M on A {}
class X = Object with [!M!];
```
#### Common fixes
If you need to use the mixin, then change the superclass to be either the
same as or a subclass of the superclass constraint:
```dart
class A {}
mixin M on A {}
class X = A with M;
```
MIXIN_APPLICATION_NO_CONCRETE_SUPER_INVOKED_SETTER:
sharedName: MIXIN_APPLICATION_NO_CONCRETE_SUPER_INVOKED_MEMBER
problemMessage: "The class doesn't have a concrete implementation of the super-invoked setter '{0}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the display name of the setter without a concrete implementation
MIXIN_APPLICATION_NO_CONCRETE_SUPER_INVOKED_MEMBER:
problemMessage: "The class doesn't have a concrete implementation of the super-invoked member '{0}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the display name of the member without a concrete implementation
documentation: |-
#### Description
The analyzer produces this diagnostic when a [mixin application][] contains
an invocation of a member from its superclass, and there's no concrete
member of that name in the mixin application's superclass.
#### Example
The following code produces this diagnostic because the mixin `M` contains
the invocation `super.m()`, and the class `A`, which is the superclass of
the [mixin application][] `A+M`, doesn't define a concrete implementation
of `m`:
```dart
abstract class A {
void m();
}
mixin M on A {
void bar() {
super.m();
}
}
abstract class B extends A with [!M!] {}
```
#### Common fixes
If you intended to apply the mixin `M` to a different class, one that has a
concrete implementation of `m`, then change the superclass of `B` to that
class:
```dart
abstract class A {
void m();
}
mixin M on A {
void bar() {
super.m();
}
}
class C implements A {
void m() {}
}
abstract class B extends C with M {}
```
If you need to make `B` a subclass of `A`, then add a concrete
implementation of `m` in `A`:
```dart
abstract class A {
void m() {}
}
mixin M on A {
void bar() {
super.m();
}
}
abstract class B extends A with M {}
```
MIXIN_CLASS_DECLARATION_EXTENDS_NOT_OBJECT:
problemMessage: "The class '{0}' can't be declared a mixin because it extends a class other than 'Object'."
correctionMessage: Try removing the 'mixin' modifier or changing the superclass to 'Object'.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the mixin class that is invalid
documentation: |-
#### Description
The analyzer produces this diagnostic when a class that is marked with
the `mixin` modifier extends a class other than `Object`. A mixin class
can't have a superclass other than `Object`.
#### Example
The following code produces this diagnostic because the class `B`, which
has the modifier `mixin`, extends `A`:
```dart
class A {}
mixin class B extends [!A!] {}
```
#### Common fixes
If you want the class to be used as a mixin, then change the superclass to
`Object`, either explicitly or by removing the extends clause:
```dart
class A {}
mixin class B {}
```
If the class needs to have a superclass other than `Object`, then remove
the `mixin` modifier:
```dart
class A {}
class B extends A {}
```
If you need both a mixin and a subclass of a class other than `Object`,
then move the members of the subclass to a new mixin, remove the `mixin`
modifier from the subclass, and apply the new mixin to the subclass:
```dart
class A {}
class B extends A with M {}
mixin M {}
```
Depending on the members of the subclass this might require adding an `on`
clause to the mixin.
MIXIN_CLASS_DECLARES_CONSTRUCTOR:
problemMessage: "The class '{0}' can't be used as a mixin because it declares a constructor."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the mixin that is invalid
documentation: |-
#### Description
The analyzer produces this diagnostic when a class is used as a mixin and
the mixed-in class defines a constructor.
#### Example
The following code produces this diagnostic because the class `A`, which
defines a constructor, is being used as a mixin:
```dart
//@dart=2.19
class A {
A();
}
class B with [!A!] {}
```
#### Common fixes
If it's possible to convert the class to a mixin, then do so:
```dart
mixin A {
}
class B with A {}
```
If the class can't be a mixin and it's possible to remove the constructor,
then do so:
```dart
//@dart=2.19
class A {
}
class B with A {}
```
If the class can't be a mixin and you can't remove the constructor, then
try extending or implementing the class rather than mixing it in:
```dart
class A {
A();
}
class B extends A {}
```
MIXIN_INHERITS_FROM_NOT_OBJECT:
problemMessage: "The class '{0}' can't be used as a mixin because it extends a class other than 'Object'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the mixin that is invalid
documentation: |-
#### Description
The analyzer produces this diagnostic when a class that extends a class
other than `Object` is used as a mixin.
#### Example
The following code produces this diagnostic because the class `B`, which
extends `A`, is being used as a mixin by `C`:
```dart
//@dart=2.19
class A {}
class B extends A {}
class C with [!B!] {}
```
#### Common fixes
If the class being used as a mixin can be changed to extend `Object`, then
change it:
```dart
//@dart=2.19
class A {}
class B {}
class C with B {}
```
If the class being used as a mixin can't be changed and the class that's
using it extends `Object`, then extend the class being used as a mixin:
```dart
class A {}
class B extends A {}
class C extends B {}
```
If the class doesn't extend `Object` or if you want to be able to mix in
the behavior from `B` in other places, then create a real mixin:
```dart
class A {}
mixin M on A {}
class B extends A with M {}
class C extends A with M {}
```
MIXIN_INSTANTIATE:
problemMessage: "Mixins can't be instantiated."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a mixin is instantiated.
#### Example
The following code produces this diagnostic because the mixin `M` is being
instantiated:
```dart
mixin M {}
var m = [!M!]();
```
#### Common fixes
If you intend to use an instance of a class, then use the name of that
class in place of the name of the mixin.
MIXIN_OF_NON_CLASS:
problemMessage: Classes can only mix in mixins and classes.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a name in a `with` clause is
defined to be something other than a mixin or a class.
#### Example
The following code produces this diagnostic because `F` is defined to be a
function type:
```dart
typedef F = int Function(String);
class C with [!F!] {}
```
#### Common fixes
Remove the invalid name from the list, possibly replacing it with the name
of the intended mixin or class:
```dart
typedef F = int Function(String);
class C {}
```
MIXIN_SUBTYPE_OF_BASE_IS_NOT_BASE:
sharedName: SUBTYPE_OF_BASE_OR_FINAL_IS_NOT_BASE_FINAL_OR_SEALED
problemMessage: "The mixin '{0}' must be 'base' because the supertype '{1}' is 'base'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the mixin that is not 'base'
1: the name of the 'base' supertype
MIXIN_SUBTYPE_OF_FINAL_IS_NOT_BASE:
sharedName: SUBTYPE_OF_BASE_OR_FINAL_IS_NOT_BASE_FINAL_OR_SEALED
problemMessage: "The mixin '{0}' must be 'base' because the supertype '{1}' is 'final'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the mixin that is not 'final'
1: the name of the 'final' supertype
MIXIN_SUPER_CLASS_CONSTRAINT_DEFERRED_CLASS:
problemMessage: "Deferred classes can't be used as superclass constraints."
correctionMessage: Try changing the import to not be deferred.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a superclass constraint of a
mixin is imported from a deferred library.
#### Example
The following code produces this diagnostic because the superclass
constraint of `math.Random` is imported from a deferred library:
```dart
import 'dart:async' deferred as async;
mixin M<T> on [!async.Stream<T>!] {}
```
#### Common fixes
If the import doesn't need to be deferred, then remove the `deferred`
keyword:
```dart
import 'dart:async' as async;
mixin M<T> on async.Stream<T> {}
```
If the import does need to be deferred, then remove the superclass
constraint:
```dart
mixin M<T> {}
```
MIXIN_SUPER_CLASS_CONSTRAINT_NON_INTERFACE:
problemMessage: Only classes and mixins can be used as superclass constraints.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a type following the `on`
keyword in a mixin declaration is neither a class nor a mixin.
#### Example
The following code produces this diagnostic because `F` is neither a class
nor a mixin:
```dart
typedef F = void Function();
mixin M on [!F!] {}
```
#### Common fixes
If the type was intended to be a class but was mistyped, then replace the
name.
Otherwise, remove the type from the `on` clause.
MIXIN_WITH_NON_CLASS_SUPERCLASS:
problemMessage: Mixin can only be applied to class.
comment: |-
9.1 Mixin Application: It is a compile-time error if <i>S</i> does not
denote a class available in the immediately enclosing scope.
MULTIPLE_REDIRECTING_CONSTRUCTOR_INVOCATIONS:
problemMessage: Constructors can have only one 'this' redirection, at most.
correctionMessage: Try removing all but one of the redirections.
comment: |-
No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a constructor redirects to more
than one other constructor in the same class (using `this`).
#### Example
The following code produces this diagnostic because the unnamed
constructor in `C` is redirecting to both `this.a` and `this.b`:
```dart
class C {
C() : this.a(), [!this.b()!];
C.a();
C.b();
}
```
#### Common fixes
Remove all but one of the redirections:
```dart
class C {
C() : this.a();
C.a();
C.b();
}
```
MULTIPLE_SUPER_INITIALIZERS:
problemMessage: "A constructor can have at most one 'super' initializer."
correctionMessage: "Try removing all but one of the 'super' initializers."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the initializer list of a
constructor contains more than one invocation of a constructor from the
superclass. The initializer list is required to have exactly one such call,
which can either be explicit or implicit.
#### Example
The following code produces this diagnostic because the initializer list
for `B`'s constructor invokes both the constructor `one` and the
constructor `two` from the superclass `A`:
```dart
class A {
int? x;
String? s;
A.one(this.x);
A.two(this.s);
}
class B extends A {
B() : super.one(0), [!super.two('')!];
}
```
#### Common fixes
If one of the super constructors will initialize the instance fully, then
remove the other:
```dart
class A {
int? x;
String? s;
A.one(this.x);
A.two(this.s);
}
class B extends A {
B() : super.one(0);
}
```
If the initialization achieved by one of the super constructors can be
performed in the body of the constructor, then remove its super invocation
and perform the initialization in the body:
```dart
class A {
int? x;
String? s;
A.one(this.x);
A.two(this.s);
}
class B extends A {
B() : super.one(0) {
s = '';
}
}
```
If the initialization can only be performed in a constructor in the
superclass, then either add a new constructor or modify one of the existing
constructors so there's a constructor that allows all the required
initialization to occur in a single call:
```dart
class A {
int? x;
String? s;
A.one(this.x);
A.two(this.s);
A.three(this.x, this.s);
}
class B extends A {
B() : super.three(0, '');
}
```
NEW_WITH_UNDEFINED_CONSTRUCTOR:
problemMessage: "The class '{0}' doesn't have a constructor named '{1}'."
correctionMessage: "Try invoking a different constructor, or define a constructor named '{1}'."
comment: |-
12.11.1 New: If <i>T</i> is a class or parameterized type accessible in the
current scope then:
1. If <i>e</i> is of the form <i>new T.id(a<sub>1</sub>, &hellip;,
a<sub>n</sub>, x<sub>n+1</sub>: a<sub>n+1</sub>, &hellip;,
x<sub>n+k</sub>: a<sub>n+k</sub>)</i> it is a static warning if
<i>T.id</i> is not the name of a constructor declared by the type
<i>T</i>.
If <i>e</i> of the form <i>new T(a<sub>1</sub>, &hellip;, a<sub>n</sub>,
x<sub>n+1</sub>: a<sub>n+1</sub>, &hellip;, x<sub>n+k</sub>:
a<sub>n+kM/sub>)</i> it is a static warning if the type <i>T</i> does not
declare a constructor with the same name as the declaration of <i>T</i>.
Parameters:
0: the name of the class being instantiated
1: the name of the constructor
NEW_WITH_UNDEFINED_CONSTRUCTOR_DEFAULT:
problemMessage: "The class '{0}' doesn't have an unnamed constructor."
correctionMessage: "Try using one of the named constructors defined in '{0}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the class being instantiated
documentation: |-
#### Description
The analyzer produces this diagnostic when an unnamed constructor is
invoked on a class that defines named constructors but the class doesn't
have an unnamed constructor.
#### Example
The following code produces this diagnostic because `A` doesn't define an
unnamed constructor:
```dart
class A {
A.a();
}
A f() => [!A!]();
```
#### Common fixes
If one of the named constructors does what you need, then use it:
```dart
class A {
A.a();
}
A f() => A.a();
```
If none of the named constructors does what you need, and you're able to
add an unnamed constructor, then add the constructor:
```dart
class A {
A();
A.a();
}
A f() => A();
```
NON_ABSTRACT_CLASS_INHERITS_ABSTRACT_MEMBER_FIVE_PLUS:
sharedName: NON_ABSTRACT_CLASS_INHERITS_ABSTRACT_MEMBER
problemMessage: "Missing concrete implementations of '{0}', '{1}', '{2}', '{3}', and {4} more."
correctionMessage: Try implementing the missing methods, or make the class abstract.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the first member
1: the name of the second member
2: the name of the third member
3: the name of the fourth member
4: the number of additional missing members that aren't listed
NON_ABSTRACT_CLASS_INHERITS_ABSTRACT_MEMBER_FOUR:
sharedName: NON_ABSTRACT_CLASS_INHERITS_ABSTRACT_MEMBER
problemMessage: "Missing concrete implementations of '{0}', '{1}', '{2}', and '{3}'."
correctionMessage: Try implementing the missing methods, or make the class abstract.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the first member
1: the name of the second member
2: the name of the third member
3: the name of the fourth member
NON_ABSTRACT_CLASS_INHERITS_ABSTRACT_MEMBER_ONE:
sharedName: NON_ABSTRACT_CLASS_INHERITS_ABSTRACT_MEMBER
problemMessage: "Missing concrete implementation of '{0}'."
correctionMessage: Try implementing the missing method, or make the class abstract.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the member
documentation: |-
#### Description
The analyzer produces this diagnostic when a concrete class inherits one or
more abstract members, and doesn't provide or inherit an implementation for
at least one of those abstract members.
#### Example
The following code produces this diagnostic because the class `B` doesn't
have a concrete implementation of `m`:
```dart
abstract class A {
void m();
}
class [!B!] extends A {}
```
#### Common fixes
If the subclass can provide a concrete implementation for some or all of
the abstract inherited members, then add the concrete implementations:
```dart
abstract class A {
void m();
}
class B extends A {
void m() {}
}
```
If there is a mixin that provides an implementation of the inherited
methods, then apply the mixin to the subclass:
```dart
abstract class A {
void m();
}
class B extends A with M {}
mixin M {
void m() {}
}
```
If the subclass can't provide a concrete implementation for all of the
abstract inherited members, then mark the subclass as being abstract:
```dart
abstract class A {
void m();
}
abstract class B extends A {}
```
NON_ABSTRACT_CLASS_INHERITS_ABSTRACT_MEMBER_THREE:
sharedName: NON_ABSTRACT_CLASS_INHERITS_ABSTRACT_MEMBER
problemMessage: "Missing concrete implementations of '{0}', '{1}', and '{2}'."
correctionMessage: Try implementing the missing methods, or make the class abstract.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the first member
1: the name of the second member
2: the name of the third member
NON_ABSTRACT_CLASS_INHERITS_ABSTRACT_MEMBER_TWO:
sharedName: NON_ABSTRACT_CLASS_INHERITS_ABSTRACT_MEMBER
problemMessage: "Missing concrete implementations of '{0}' and '{1}'."
correctionMessage: Try implementing the missing methods, or make the class abstract.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the first member
1: the name of the second member
NON_BOOL_CONDITION:
problemMessage: "Conditions must have a static type of 'bool'."
correctionMessage: Try changing the condition.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a condition, such as an `if` or
`while` loop, doesn't have the static type `bool`.
#### Example
The following code produces this diagnostic because `x` has the static type
`int`:
```dart
void f(int x) {
if ([!x!]) {
// ...
}
}
```
#### Common fixes
Change the condition so that it produces a Boolean value:
```dart
void f(int x) {
if (x == 0) {
// ...
}
}
```
NON_BOOL_EXPRESSION:
problemMessage: "The expression in an assert must be of type 'bool'."
correctionMessage: Try changing the expression.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the first expression in an
assert has a type other than `bool`.
#### Example
The following code produces this diagnostic because the type of `p` is
`int`, but a `bool` is required:
```dart
void f(int p) {
assert([!p!]);
}
```
#### Common fixes
Change the expression so that it has the type `bool`:
```dart
void f(int p) {
assert(p > 0);
}
```
NON_BOOL_NEGATION_EXPRESSION:
problemMessage: "A negation operand must have a static type of 'bool'."
correctionMessage: "Try changing the operand to the '!' operator."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the operand of the unary
negation operator (`!`) doesn't have the type `bool`.
#### Example
The following code produces this diagnostic because `x` is an `int` when it
must be a `bool`:
```dart
int x = 0;
bool y = ![!x!];
```
#### Common fixes
Replace the operand with an expression that has the type `bool`:
```dart
int x = 0;
bool y = !(x > 0);
```
NON_BOOL_OPERAND:
problemMessage: "The operands of the operator '{0}' must be assignable to 'bool'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the lexeme of the logical operator
documentation: |-
#### Description
The analyzer produces this diagnostic when one of the operands of either
the `&&` or `||` operator doesn't have the type `bool`.
#### Example
The following code produces this diagnostic because `a` isn't a Boolean
value:
```dart
int a = 3;
bool b = [!a!] || a > 1;
```
#### Common fixes
Change the operand to a Boolean value:
```dart
int a = 3;
bool b = a == 0 || a > 1;
```
NON_CONSTANT_ANNOTATION_CONSTRUCTOR:
problemMessage: Annotation creation can only call a const constructor.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when an annotation is the invocation
of an existing constructor even though the invoked constructor isn't a
const constructor.
#### Example
The following code produces this diagnostic because the constructor for `C`
isn't a const constructor:
```dart
[!@C()!]
void f() {
}
class C {
C();
}
```
#### Common fixes
If it's valid for the class to have a const constructor, then create a
const constructor that can be used for the annotation:
```dart
@C()
void f() {
}
class C {
const C();
}
```
If it isn't valid for the class to have a const constructor, then either
remove the annotation or use a different class for the annotation.
NON_CONSTANT_CASE_EXPRESSION:
problemMessage: Case expressions must be constant.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the expression in a `case`
clause isn't a constant expression.
#### Example
The following code produces this diagnostic because `j` isn't a constant:
```dart
%language=2.18
void f(int i, int j) {
switch (i) {
case [!j!]:
// ...
break;
}
}
```
#### Common fixes
Either make the expression a constant expression, or rewrite the `switch`
statement as a sequence of `if` statements:
```dart
void f(int i, int j) {
if (i == j) {
// ...
}
}
```
NON_CONSTANT_CASE_EXPRESSION_FROM_DEFERRED_LIBRARY:
problemMessage: "Constant values from a deferred library can't be used as a case expression."
correctionMessage: Try re-writing the switch as a series of if statements, or changing the import to not be deferred.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the expression in a case clause
references a constant from a library that is imported using a deferred
import. In order for switch statements to be compiled efficiently, the
constants referenced in case clauses need to be available at compile time,
and constants from deferred libraries aren't available at compile time.
For more information, check out
[Lazily loading a library](https://dart.dev/language/libraries#lazily-loading-a-library).
#### Example
Given a file `a.dart` that defines the constant `zero`:
```dart
%uri="lib/a.dart"
const zero = 0;
```
The following code produces this diagnostic because the library `a.dart` is
imported using a `deferred` import, and the constant `a.zero`, declared in
the imported library, is used in a case clause:
```dart
%language=2.18
import 'a.dart' deferred as a;
void f(int x) {
switch (x) {
case a.[!zero!]:
// ...
break;
}
}
```
#### Common fixes
If you need to reference the constant from the imported library, then
remove the `deferred` keyword:
```dart
import 'a.dart' as a;
void f(int x) {
switch (x) {
case a.zero:
// ...
break;
}
}
```
If you need to reference the constant from the imported library and also
need the imported library to be deferred, then rewrite the switch statement
as a sequence of `if` statements:
```dart
import 'a.dart' deferred as a;
void f(int x) {
if (x == a.zero) {
// ...
}
}
```
If you don't need to reference the constant, then replace the case
expression:
```dart
void f(int x) {
switch (x) {
case 0:
// ...
break;
}
}
```
NON_CONSTANT_DEFAULT_VALUE:
problemMessage: The default value of an optional parameter must be constant.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when an optional parameter, either
named or positional, has a default value that isn't a compile-time
constant.
#### Example
The following code produces this diagnostic:
```dart
%language=2.9
var defaultValue = 3;
void f([int value = [!defaultValue!]]) {}
```
#### Common fixes
If the default value can be converted to be a constant, then convert it:
```dart
%language=2.9
const defaultValue = 3;
void f([int value = defaultValue]) {}
```
If the default value needs to change over time, then apply the default
value inside the function:
```dart
%language=2.9
var defaultValue = 3;
void f([int value]) {
value ??= defaultValue;
}
```
NON_CONSTANT_DEFAULT_VALUE_FROM_DEFERRED_LIBRARY:
problemMessage: "Constant values from a deferred library can't be used as a default parameter value."
correctionMessage: Try leaving the default as null and initializing the parameter inside the function body.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the default value of an optional
parameter uses a constant from a library imported using a deferred import.
Default values need to be available at compile time, and constants from
deferred libraries aren't available at compile time.
For more information, check out
[Lazily loading a library](https://dart.dev/language/libraries#lazily-loading-a-library).
#### Example
Given a file `a.dart` that defines the constant `zero`:
```dart
%uri="lib/a.dart"
const zero = 0;
```
The following code produces this diagnostic because `zero` is declared in a
library imported using a deferred import:
```dart
import 'a.dart' deferred as a;
void f({int x = a.[!zero!]}) {}
```
#### Common fixes
If you need to reference the constant from the imported library, then
remove the `deferred` keyword:
```dart
import 'a.dart' as a;
void f({int x = a.zero}) {}
```
If you don't need to reference the constant, then replace the default
value:
```dart
void f({int x = 0}) {}
```
NON_CONSTANT_LIST_ELEMENT:
problemMessage: The values in a const list literal must be constants.
correctionMessage: "Try removing the keyword 'const' from the list literal."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when an element in a constant list
literal isn't a constant value. The list literal can be constant either
explicitly (because it's prefixed by the `const` keyword) or implicitly
(because it appears in a [constant context][]).
#### Example
The following code produces this diagnostic because `x` isn't a constant,
even though it appears in an implicitly constant list literal:
```dart
var x = 2;
var y = const <int>[0, 1, [!x!]];
```
#### Common fixes
If the list needs to be a constant list, then convert the element to be a
constant. In the example above, you might add the `const` keyword to the
declaration of `x`:
```dart
const x = 2;
var y = const <int>[0, 1, x];
```
If the expression can't be made a constant, then the list can't be a
constant either, so you must change the code so that the list isn't a
constant. In the example above this means removing the `const` keyword
before the list literal:
```dart
var x = 2;
var y = <int>[0, 1, x];
```
NON_CONSTANT_MAP_ELEMENT:
problemMessage: The elements in a const map literal must be constant.
correctionMessage: "Try removing the keyword 'const' from the map literal."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when an `if` element or a spread
element in a constant map isn't a constant element.
#### Examples
The following code produces this diagnostic because it's attempting to
spread a non-constant map:
```dart
var notConst = <int, int>{};
var map = const <int, int>{...[!notConst!]};
```
Similarly, the following code produces this diagnostic because the
condition in the `if` element isn't a constant expression:
```dart
bool notConst = true;
var map = const <int, int>{if ([!notConst!]) 1 : 2};
```
#### Common fixes
If the map needs to be a constant map, then make the elements constants.
In the spread example, you might do that by making the collection being
spread a constant:
```dart
const notConst = <int, int>{};
var map = const <int, int>{...notConst};
```
If the map doesn't need to be a constant map, then remove the `const`
keyword:
```dart
bool notConst = true;
var map = <int, int>{if (notConst) 1 : 2};
```
NON_CONSTANT_MAP_KEY:
problemMessage: The keys in a const map literal must be constant.
correctionMessage: "Try removing the keyword 'const' from the map literal."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a key in a constant map literal
isn't a constant value.
#### Example
The following code produces this diagnostic because `a` isn't a constant:
```dart
var a = 'a';
var m = const {[!a!]: 0};
```
#### Common fixes
If the map needs to be a constant map, then make the key a constant:
```dart
const a = 'a';
var m = const {a: 0};
```
If the map doesn't need to be a constant map, then remove the `const`
keyword:
```dart
var a = 'a';
var m = {a: 0};
```
NON_CONSTANT_MAP_PATTERN_KEY:
problemMessage: Key expressions in map patterns must be constants.
correctionMessage: Try using constants instead.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a key in a map pattern isn't a
constant expression.
#### Example
The following code produces this diagnostic because the key `A()` isn't a
constant:
```dart
void f(Object x) {
if (x case {[!A()!]: 0}) {}
}
class A {
const A();
}
```
#### Common fixes
Use a constant for the key:
```dart
void f(Object x) {
if (x case {const A(): 0}) {}
}
class A {
const A();
}
```
NON_CONSTANT_MAP_VALUE:
problemMessage: The values in a const map literal must be constant.
correctionMessage: "Try removing the keyword 'const' from the map literal."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a value in a constant map
literal isn't a constant value.
#### Example
The following code produces this diagnostic because `a` isn't a constant:
```dart
var a = 'a';
var m = const {0: [!a!]};
```
#### Common fixes
If the map needs to be a constant map, then make the key a constant:
```dart
const a = 'a';
var m = const {0: a};
```
If the map doesn't need to be a constant map, then remove the `const`
keyword:
```dart
var a = 'a';
var m = {0: a};
```
NON_CONSTANT_RELATIONAL_PATTERN_EXPRESSION:
problemMessage: The relational pattern expression must be a constant.
correctionMessage: Try using a constant instead.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the value in a relational
pattern expression isn't a constant expression.
#### Example
The following code produces this diagnostic because the operand of the `>`
operator, `a`, isn't a constant:
```dart
final a = 0;
void f(int x) {
if (x case > [!a!]) {}
}
```
#### Common fixes
Replace the value with a constant expression:
```dart
const a = 0;
void f(int x) {
if (x case > a) {}
}
```
NON_CONSTANT_SET_ELEMENT:
problemMessage: The values in a const set literal must be constants.
correctionMessage: "Try removing the keyword 'const' from the set literal."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a constant set literal contains
an element that isn't a compile-time constant.
#### Example
The following code produces this diagnostic because `i` isn't a constant:
```dart
var i = 0;
var s = const {[!i!]};
```
#### Common fixes
If the element can be changed to be a constant, then change it:
```dart
const i = 0;
var s = const {i};
```
If the element can't be a constant, then remove the keyword `const`:
```dart
var i = 0;
var s = {i};
```
NON_CONST_MAP_AS_EXPRESSION_STATEMENT:
problemMessage: "A non-constant map or set literal without type arguments can't be used as an expression statement."
comment: |-
13.2 Expression Statements: It is a compile-time error if a non-constant
map literal that has no explicit type arguments appears in a place where a
statement is expected.
NON_COVARIANT_TYPE_PARAMETER_POSITION_IN_REPRESENTATION_TYPE:
problemMessage: "An extension type parameter can't be used in a non-covariant position of its representation type."
correctionMessage: "Try removing the type parameters from function parameter types and type parameter bounds."
comment: No parameters.
NON_EXHAUSTIVE_SWITCH_EXPRESSION:
problemMessage: "The type '{0}' is not exhaustively matched by the switch cases since it doesn't match '{1}'."
correctionMessage: "Try adding a wildcard pattern or cases that match '{2}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the type of the switch scrutinee
1: the witness pattern for the unmatched value
2: the suggested pattern for the unmatched value
documentation: |-
#### Description
The analyzer produces this diagnostic when a `switch` expression is
missing a case for one or more of the possible values that could flow
through it.
#### Example
The following code produces this diagnostic because the switch expression
doesn't have a case for the value `E.three`:
```dart
enum E { one, two, three }
String f(E e) => [!switch!] (e) {
E.one => 'one',
E.two => 'two',
};
```
#### Common fixes
If the missing values are distinctly meaningful to the switch expression,
then add a case for each of the values missing a match:
```dart
enum E { one, two, three }
String f(E e) => switch (e) {
E.one => 'one',
E.two => 'two',
E.three => 'three',
};
```
If the missing values don't need to be matched, then add a wildcard
pattern that returns a simple default:
```dart
enum E { one, two, three }
String f(E e) => switch (e) {
E.one => 'one',
E.two => 'two',
_ => 'unknown',
};
```
Be aware that a wildcard pattern will handle any values added to the type
in the future. You will lose the ability to have the compiler warn you if
the `switch` needs to be updated to account for newly added types.
NON_EXHAUSTIVE_SWITCH_STATEMENT:
problemMessage: "The type '{0}' is not exhaustively matched by the switch cases since it doesn't match '{1}'."
correctionMessage: "Try adding a default case or cases that match '{2}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the type of the switch scrutinee
1: the witness pattern for the unmatched value
2: the suggested pattern for the unmatched value
documentation: |-
#### Description
The analyzer produces this diagnostic when a `switch` statement switching
over an exhaustive type is missing a case for one or more of the possible
values that could flow through it.
#### Example
The following code produces this diagnostic because the switch statement
doesn't have a case for the value `E.three`, and `E` is an exhaustive
type:
```dart
enum E { one, two, three }
void f(E e) {
[!switch!] (e) {
case E.one:
case E.two:
}
}
```
#### Common fixes
Add a case for each of the constants that aren't currently being matched:
```dart
enum E { one, two, three }
void f(E e) {
switch (e) {
case E.one:
case E.two:
break;
case E.three:
}
}
```
If the missing values don't need to be matched, then add a `default`
clause or a wildcard pattern:
```dart
enum E { one, two, three }
void f(E e) {
switch (e) {
case E.one:
case E.two:
break;
default:
}
}
```
But be aware that adding a `default` clause or wildcard pattern will cause
any future values of the exhaustive type to also be handled, so you will
have lost the ability for the compiler to warn you if the `switch` needs
to be updated.
NON_FINAL_FIELD_IN_ENUM:
problemMessage: Enums can only declare final fields.
correctionMessage: Try making the field final.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when an instance field in an enum
isn't marked as `final`.
#### Example
The following code produces this diagnostic because the field `f` isn't a
final field:
```dart
enum E {
c;
int [!f!] = 0;
}
```
#### Common fixes
If the field must be defined for the enum, then mark the field as being
`final`:
```dart
enum E {
c;
final int f = 0;
}
```
If the field can be removed, then remove it:
```dart
enum E {
c
}
```
NON_GENERATIVE_CONSTRUCTOR:
problemMessage: "The generative constructor '{0}' is expected, but a factory was found."
correctionMessage: Try calling a different constructor of the superclass, or making the called constructor not be a factory constructor.
hasPublishedDocs: true
comment: |-
Parameters:
0: the non-generative constructor
documentation: |-
#### Description
The analyzer produces this diagnostic when the initializer list of a
constructor invokes a constructor from the superclass, and the invoked
constructor is a factory constructor. Only a generative constructor can be
invoked in the initializer list.
#### Example
The following code produces this diagnostic because the invocation of the
constructor `super.one()` is invoking a factory constructor:
```dart
class A {
factory A.one() = B;
A.two();
}
class B extends A {
B() : [!super.one()!];
}
```
#### Common fixes
Change the super invocation to invoke a generative constructor:
```dart
class A {
factory A.one() = B;
A.two();
}
class B extends A {
B() : super.two();
}
```
If the generative constructor is the unnamed constructor, and if there are
no arguments being passed to it, then you can remove the super invocation.
NON_GENERATIVE_IMPLICIT_CONSTRUCTOR:
problemMessage: "The unnamed constructor of superclass '{0}' (called by the default constructor of '{1}') must be a generative constructor, but factory found."
correctionMessage: "Try adding an explicit constructor that has a different superinitializer or changing the superclass constructor '{2}' to not be a factory constructor."
comment: |-
Parameters:
0: the name of the superclass
1: the name of the current class
2: the implicitly called factory constructor of the superclass
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a class has an implicit
generative constructor and the superclass has an explicit unnamed factory
constructor. The implicit constructor in the subclass implicitly invokes
the unnamed constructor in the superclass, but generative constructors can
only invoke another generative constructor, not a factory constructor.
#### Example
The following code produces this diagnostic because the implicit
constructor in `B` invokes the unnamed constructor in `A`, but the
constructor in `A` is a factory constructor, when a generative constructor
is required:
```dart
class A {
factory A() => throw 0;
A.named();
}
class [!B!] extends A {}
```
#### Common fixes
If the unnamed constructor in the superclass can be a generative
constructor, then change it to be a generative constructor:
```dart
class A {
A();
A.named();
}
class B extends A { }
```
If the unnamed constructor can't be a generative constructor and there are
other generative constructors in the superclass, then explicitly invoke
one of them:
```dart
class A {
factory A() => throw 0;
A.named();
}
class B extends A {
B() : super.named();
}
```
If there are no generative constructors that can be used and none can be
added, then implement the superclass rather than extending it:
```dart
class A {
factory A() => throw 0;
A.named();
}
class B implements A {}
```
NON_SYNC_FACTORY:
problemMessage: "Factory bodies can't use 'async', 'async*', or 'sync*'."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the body of a factory
constructor is marked with `async`, `async*`, or `sync*`. All constructors,
including factory constructors, are required to return an instance of the
class in which they're declared, not a `Future`, `Stream`, or `Iterator`.
#### Example
The following code produces this diagnostic because the body of the factory
constructor is marked with `async`:
```dart
class C {
factory C() [!async!] {
return C._();
}
C._();
}
```
#### Common fixes
If the member must be declared as a factory constructor, then remove the
keyword appearing before the body:
```dart
class C {
factory C() {
return C._();
}
C._();
}
```
If the member must return something other than an instance of the enclosing
class, then make the member a static method:
```dart
class C {
static Future<C> m() async {
return C._();
}
C._();
}
```
NON_TYPE_AS_TYPE_ARGUMENT:
problemMessage: "The name '{0}' isn't a type, so it can't be used as a type argument."
correctionMessage: "Try correcting the name to an existing type, or defining a type named '{0}'."
isUnresolvedIdentifier: true
hasPublishedDocs: true
comment: |-
Parameters:
0: the name appearing where a type is expected
documentation: |-
#### Description
The analyzer produces this diagnostic when an identifier that isn't a type
is used as a type argument.
#### Example
The following code produces this diagnostic because `x` is a variable, not
a type:
```dart
var x = 0;
List<[!x!]> xList = [];
```
#### Common fixes
Change the type argument to be a type:
```dart
var x = 0;
List<int> xList = [];
```
NON_TYPE_IN_CATCH_CLAUSE:
problemMessage: "The name '{0}' isn't a type and can't be used in an on-catch clause."
correctionMessage: Try correcting the name to match an existing class.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the non-type element
documentation: |-
#### Description
The analyzer produces this diagnostic when the identifier following the
`on` in a `catch` clause is defined to be something other than a type.
#### Example
The following code produces this diagnostic because `f` is a function, not
a type:
```dart
%language=2.9
void f() {
try {
// ...
} on [!f!] {
// ...
}
}
```
#### Common fixes
Change the name to the type of object that should be caught:
```dart
%language=2.9
void f() {
try {
// ...
} on FormatException {
// ...
}
}
```
NON_VOID_RETURN_FOR_OPERATOR:
problemMessage: "The return type of the operator []= must be 'void'."
correctionMessage: "Try changing the return type to 'void'."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a declaration of the operator
`[]=` has a return type other than `void`.
#### Example
The following code produces this diagnostic because the declaration of the
operator `[]=` has a return type of `int`:
```dart
class C {
[!int!] operator []=(int index, int value) => 0;
}
```
#### Common fixes
Change the return type to `void`:
```dart
class C {
void operator []=(int index, int value) => 0;
}
```
NON_VOID_RETURN_FOR_SETTER:
problemMessage: "The return type of the setter must be 'void' or absent."
correctionMessage: Try removing the return type, or define a method rather than a setter.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a setter is defined with a
return type other than `void`.
#### Example
The following code produces this diagnostic because the setter `p` has a
return type of `int`:
```dart
class C {
[!int!] set p(int i) => 0;
}
```
#### Common fixes
Change the return type to `void` or omit the return type:
```dart
class C {
set p(int i) => 0;
}
```
NOT_ASSIGNED_POTENTIALLY_NON_NULLABLE_LOCAL_VARIABLE:
problemMessage: "The non-nullable local variable '{0}' must be assigned before it can be used."
correctionMessage: "Try giving it an initializer expression, or ensure that it's assigned on every execution path."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the variable that is invalid
documentation: |-
#### Description
The analyzer produces this diagnostic when a local variable is referenced
and has all these characteristics:
- Has a type that's [potentially non-nullable][].
- Doesn't have an initializer.
- Isn't marked as `late`.
- The analyzer can't prove that the local variable will be assigned before
the reference based on the specification of [definite assignment][].
#### Examples
The following code produces this diagnostic because `x` can't have a value
of `null`, but is referenced before a value was assigned to it:
```dart
String f() {
int x;
return [!x!].toString();
}
```
The following code produces this diagnostic because the assignment to `x`
might not be executed, so it might have a value of `null`:
```dart
int g(bool b) {
int x;
if (b) {
x = 1;
}
return [!x!] * 2;
}
```
The following code produces this diagnostic because the analyzer can't
prove, based on definite assignment analysis, that `x` won't be referenced
without having a value assigned to it:
```dart
int h(bool b) {
int x;
if (b) {
x = 1;
}
if (b) {
return [!x!] * 2;
}
return 0;
}
```
#### Common fixes
If `null` is a valid value, then make the variable nullable:
```dart
String f() {
int? x;
return x!.toString();
}
```
If `null` isn't a valid value, and there's a reasonable default value, then
add an initializer:
```dart
int g(bool b) {
int x = 2;
if (b) {
x = 1;
}
return x * 2;
}
```
Otherwise, ensure that a value was assigned on every possible code path
before the value is accessed:
```dart
int g(bool b) {
int x;
if (b) {
x = 1;
} else {
x = 2;
}
return x * 2;
}
```
You can also mark the variable as `late`, which removes the diagnostic, but
if the variable isn't assigned a value before it's accessed, then it
results in an exception being thrown at runtime. This approach should only
be used if you're sure that the variable will always be assigned, even
though the analyzer can't prove it based on definite assignment analysis.
```dart
int h(bool b) {
late int x;
if (b) {
x = 1;
}
if (b) {
return x * 2;
}
return 0;
}
```
NOT_A_TYPE:
problemMessage: "{0} isn't a type."
correctionMessage: Try correcting the name to match an existing type.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name that is not a type
documentation: |-
#### Description
The analyzer produces this diagnostic when a name is used as a type but
declared to be something other than a type.
#### Example
The following code produces this diagnostic because `f` is a function:
```dart
f() {}
g([!f!] v) {}
```
#### Common fixes
Replace the name with the name of a type.
NOT_BINARY_OPERATOR:
problemMessage: "'{0}' isn't a binary operator."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the operator that is not a binary operator.
documentation: |-
#### Description
The analyzer produces this diagnostic when an operator that can only be
used as a unary operator is used as a binary operator.
#### Example
The following code produces this diagnostic because the operator `~` can
only be used as a unary operator:
```dart
var a = 5 [!~!] 3;
```
#### Common fixes
Replace the operator with the correct binary operator:
```dart
var a = 5 - 3;
```
NOT_ENOUGH_POSITIONAL_ARGUMENTS_SINGULAR:
sharedName: NOT_ENOUGH_POSITIONAL_ARGUMENTS
problemMessage: "1 positional argument expected, but 0 found."
correctionMessage: Try adding the missing argument.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a method or function invocation
has fewer positional arguments than the number of required positional
parameters.
#### Example
The following code produces this diagnostic because `f` declares two
required parameters, but only one argument is provided:
```dart
void f(int a, int b) {}
void g() {
f(0[!)!];
}
```
#### Common fixes
Add arguments corresponding to the remaining parameters:
```dart
void f(int a, int b) {}
void g() {
f(0, 1);
}
```
NOT_ENOUGH_POSITIONAL_ARGUMENTS_PLURAL:
sharedName: NOT_ENOUGH_POSITIONAL_ARGUMENTS
problemMessage: "{0} positional arguments expected, but {1} found."
correctionMessage: Try adding the missing arguments.
hasPublishedDocs: true
comment: |-
Parameters:
0: the expected number of required arguments
1: the actual number of positional arguments given
NOT_ENOUGH_POSITIONAL_ARGUMENTS_NAME_SINGULAR:
sharedName: NOT_ENOUGH_POSITIONAL_ARGUMENTS
problemMessage: "1 positional argument expected by '{0}', but 0 found."
correctionMessage: Try adding the missing argument.
hasPublishedDocs: true
comment: |-
Parameters:
0: name of the function or method
NOT_ENOUGH_POSITIONAL_ARGUMENTS_NAME_PLURAL:
sharedName: NOT_ENOUGH_POSITIONAL_ARGUMENTS
problemMessage: "{0} positional arguments expected by '{2}', but {1} found."
correctionMessage: Try adding the missing arguments.
hasPublishedDocs: true
comment: |-
Parameters:
0: the expected number of required arguments
1: the actual number of positional arguments given
2: name of the function or method
NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD:
problemMessage: "Non-nullable instance field '{0}' must be initialized."
correctionMessage: "Try adding an initializer expression, or a generative constructor that initializes it, or mark it 'late'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the field that is not initialized
documentation: |-
#### Description
The analyzer produces this diagnostic when a field is declared and has all
these characteristics:
- Has a type that's [potentially non-nullable][]
- Doesn't have an initializer
- Isn't marked as `late`
#### Examples
The following code produces this diagnostic because `x` is implicitly
initialized to `null` when it isn't allowed to be `null`:
```dart
class C {
int [!x!];
}
```
Similarly, the following code produces this diagnostic because `x` is
implicitly initialized to `null`, when it isn't allowed to be `null`, by
one of the constructors, even though it's initialized by other
constructors:
```dart
class C {
int x;
C(this.x);
[!C!].n();
}
```
#### Common fixes
If there's a reasonable default value for the field that's the same for all
instances, then add an initializer expression:
```dart
class C {
int x = 0;
}
```
If the value of the field should be provided when an instance is created,
then add a constructor that sets the value of the field or update an
existing constructor:
```dart
class C {
int x;
C(this.x);
}
```
You can also mark the field as `late`, which removes the diagnostic, but if
the field isn't assigned a value before it's accessed, then it results in
an exception being thrown at runtime. This approach should only be used if
you're sure that the field will always be assigned before it's referenced.
```dart
class C {
late int x;
}
```
NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD_CONSTRUCTOR:
sharedName: NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD
problemMessage: "Non-nullable instance field '{0}' must be initialized."
correctionMessage: "Try adding an initializer expression, or add a field initializer in this constructor, or mark it 'late'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the field that is not initialized
NOT_INITIALIZED_NON_NULLABLE_VARIABLE:
problemMessage: "The non-nullable variable '{0}' must be initialized."
correctionMessage: Try adding an initializer expression.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the variable that is invalid
documentation: |-
#### Description
The analyzer produces this diagnostic when a static field or top-level
variable has a type that's non-nullable and doesn't have an initializer.
Fields and variables that don't have an initializer are normally
initialized to `null`, but the type of the field or variable doesn't allow
it to be set to `null`, so an explicit initializer must be provided.
#### Examples
The following code produces this diagnostic because the field `f` can't be
initialized to `null`:
```dart
class C {
static int [!f!];
}
```
Similarly, the following code produces this diagnostic because the
top-level variable `v` can't be initialized to `null`:
```dart
int [!v!];
```
#### Common fixes
If the field or variable can't be initialized to `null`, then add an
initializer that sets it to a non-null value:
```dart
class C {
static int f = 0;
}
```
If the field or variable should be initialized to `null`, then change the
type to be nullable:
```dart
int? v;
```
If the field or variable can't be initialized in the declaration but will
always be initialized before it's referenced, then mark it as being `late`:
```dart
class C {
static late int f;
}
```
NOT_INSTANTIATED_BOUND:
problemMessage: Type parameter bound types must be instantiated.
correctionMessage: Try adding type arguments to the type parameter bound.
comment: No parameters.
NOT_ITERABLE_SPREAD:
problemMessage: "Spread elements in list or set literals must implement 'Iterable'."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the static type of the
expression of a spread element that appears in either a list literal or a
set literal doesn't implement the type `Iterable`.
#### Example
The following code produces this diagnostic:
```dart
var m = <String, int>{'a': 0, 'b': 1};
var s = <String>{...[!m!]};
```
#### Common fixes
The most common fix is to replace the expression with one that produces an
iterable object:
```dart
var m = <String, int>{'a': 0, 'b': 1};
var s = <String>{...m.keys};
```
NOT_MAP_SPREAD:
problemMessage: "Spread elements in map literals must implement 'Map'."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the static type of the
expression of a spread element that appears in a map literal doesn't
implement the type `Map`.
#### Example
The following code produces this diagnostic because `l` isn't a `Map`:
```dart
var l = <String>['a', 'b'];
var m = <int, String>{...[!l!]};
```
#### Common fixes
The most common fix is to replace the expression with one that produces a
map:
```dart
var l = <String>['a', 'b'];
var m = <int, String>{...l.asMap()};
```
NOT_NULL_AWARE_NULL_SPREAD:
problemMessage: "The Null typed expression can't be used with a non-null-aware spread."
comment: No parameters.
NO_ANNOTATION_CONSTRUCTOR_ARGUMENTS:
problemMessage: Annotation creation must have arguments.
correctionMessage: Try adding an empty argument list.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when an annotation consists of a
single identifier, but that identifier is the name of a class rather than a
variable. To create an instance of the class, the identifier must be
followed by an argument list.
#### Example
The following code produces this diagnostic because `C` is a class, and a
class can't be used as an annotation without invoking a `const` constructor
from the class:
```dart
class C {
const C();
}
[!@C!]
var x;
```
#### Common fixes
Add the missing argument list:
```dart
class C {
const C();
}
@C()
var x;
```
NO_COMBINED_SUPER_SIGNATURE:
problemMessage: "Can't infer missing types in '{0}' from overridden methods: {1}."
correctionMessage: "Try providing explicit types for this method's parameters and return type."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the class where override error was detected
1: the list of candidate signatures which cannot be combined
documentation: |-
#### Description
The analyzer produces this diagnostic when there is a method declaration
for which one or more types needs to be inferred, and those types can't be
inferred because none of the overridden methods has a function type that is
a supertype of all the other overridden methods, as specified by
[override inference][].
#### Example
The following code produces this diagnostic because the method `m` declared
in the class `C` is missing both the return type and the type of the
parameter `a`, and neither of the missing types can be inferred for it:
```dart
abstract class A {
A m(String a);
}
abstract class B {
B m(int a);
}
abstract class C implements A, B {
[!m!](a);
}
```
In this example, override inference can't be performed because the
overridden methods are incompatible in these ways:
- Neither parameter type (`String` and `int`) is a supertype of the other.
- Neither return type is a subtype of the other.
#### Common fixes
If possible, add types to the method in the subclass that are consistent
with the types from all the overridden methods:
```dart
abstract class A {
A m(String a);
}
abstract class B {
B m(int a);
}
abstract class C implements A, B {
C m(Object a);
}
```
NO_DEFAULT_SUPER_CONSTRUCTOR_EXPLICIT:
sharedName: NO_DEFAULT_SUPER_CONSTRUCTOR
problemMessage: "The superclass '{0}' doesn't have a zero argument constructor."
correctionMessage: "Try declaring a zero argument constructor in '{0}', or explicitly invoking a different constructor in '{0}'."
comment: |-
Parameters:
0: the name of the superclass that does not define an implicitly invoked
constructor
NO_DEFAULT_SUPER_CONSTRUCTOR_IMPLICIT:
sharedName: NO_DEFAULT_SUPER_CONSTRUCTOR
problemMessage: "The superclass '{0}' doesn't have a zero argument constructor."
correctionMessage: "Try declaring a zero argument constructor in '{0}', or declaring a constructor in {1} that explicitly invokes a constructor in '{0}'."
comment: |-
Parameters:
0: the name of the superclass that does not define an implicitly invoked
constructor
1: the name of the subclass that does not contain any explicit constructors
NO_GENERATIVE_CONSTRUCTORS_IN_SUPERCLASS:
problemMessage: "The class '{0}' can't extend '{1}' because '{1}' only has factory constructors (no generative constructors), and '{0}' has at least one generative constructor."
correctionMessage: "Try implementing the class instead, adding a generative (not factory) constructor to the superclass '{1}', or a factory constructor to the subclass."
comment: |-
Parameters:
0: the name of the subclass
1: the name of the superclass
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a class that has at least one
generative constructor (whether explicit or implicit) has a superclass
that doesn't have any generative constructors. Every generative
constructor, except the one defined in `Object`, invokes, either
explicitly or implicitly, one of the generative constructors from its
superclass.
#### Example
The following code produces this diagnostic because the class `B` has an
implicit generative constructor that can't invoke a generative constructor
from `A` because `A` doesn't have any generative constructors:
```dart
class A {
factory A.none() => throw '';
}
class B extends [!A!] {}
```
#### Common fixes
If the superclass should have a generative constructor, then add one:
```dart
class A {
A();
factory A.none() => throw '';
}
class B extends A {}
```
If the subclass shouldn't have a generative constructor, then remove it by
adding a factory constructor:
```dart
class A {
factory A.none() => throw '';
}
class B extends A {
factory B.none() => throw '';
}
```
If the subclass must have a generative constructor but the superclass
can't have one, then implement the superclass instead:
```dart
class A {
factory A.none() => throw '';
}
class B implements A {}
```
NULLABLE_TYPE_IN_EXTENDS_CLAUSE:
problemMessage: "A class can't extend a nullable type."
correctionMessage: Try removing the question mark.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a class declaration uses an
`extends` clause to specify a superclass, and the superclass is followed by
a `?`.
It isn't valid to specify a nullable superclass because doing so would have
no meaning; it wouldn't change either the interface or implementation being
inherited by the class containing the `extends` clause.
Note, however, that it _is_ valid to use a nullable type as a type argument
to the superclass, such as `class A extends B<C?> {}`.
#### Example
The following code produces this diagnostic because `A?` is a nullable
type, and nullable types can't be used in an `extends` clause:
```dart
class A {}
class B extends [!A?!] {}
```
#### Common fixes
Remove the question mark from the type:
```dart
class A {}
class B extends A {}
```
NULLABLE_TYPE_IN_IMPLEMENTS_CLAUSE:
problemMessage: "A class or mixin can't implement a nullable type."
correctionMessage: Try removing the question mark.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a class or mixin declaration has
an `implements` clause, and an interface is followed by a `?`.
It isn't valid to specify a nullable interface because doing so would have
no meaning; it wouldn't change the interface being inherited by the class
containing the `implements` clause.
Note, however, that it _is_ valid to use a nullable type as a type argument
to the interface, such as `class A implements B<C?> {}`.
#### Example
The following code produces this diagnostic because `A?` is a nullable
type, and nullable types can't be used in an `implements` clause:
```dart
class A {}
class B implements [!A?!] {}
```
#### Common fixes
Remove the question mark from the type:
```dart
class A {}
class B implements A {}
```
NULLABLE_TYPE_IN_ON_CLAUSE:
problemMessage: "A mixin can't have a nullable type as a superclass constraint."
correctionMessage: Try removing the question mark.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a mixin declaration uses an `on`
clause to specify a superclass constraint, and the class that's specified
is followed by a `?`.
It isn't valid to specify a nullable superclass constraint because doing so
would have no meaning; it wouldn't change the interface being depended on
by the mixin containing the `on` clause.
Note, however, that it _is_ valid to use a nullable type as a type argument
to the superclass constraint, such as `mixin A on B<C?> {}`.
#### Example
The following code produces this diagnostic because `A?` is a nullable type
and nullable types can't be used in an `on` clause:
```dart
class C {}
mixin M on [!C?!] {}
```
#### Common fixes
Remove the question mark from the type:
```dart
class C {}
mixin M on C {}
```
NULLABLE_TYPE_IN_WITH_CLAUSE:
problemMessage: "A class or mixin can't mix in a nullable type."
correctionMessage: Try removing the question mark.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a class or mixin declaration has
a `with` clause, and a mixin is followed by a `?`.
It isn't valid to specify a nullable mixin because doing so would have no
meaning; it wouldn't change either the interface or implementation being
inherited by the class containing the `with` clause.
Note, however, that it _is_ valid to use a nullable type as a type argument
to the mixin, such as `class A with B<C?> {}`.
#### Example
The following code produces this diagnostic because `A?` is a nullable
type, and nullable types can't be used in a `with` clause:
```dart
mixin M {}
class C with [!M?!] {}
```
#### Common fixes
Remove the question mark from the type:
```dart
mixin M {}
class C with M {}
```
OBJECT_CANNOT_EXTEND_ANOTHER_CLASS:
problemMessage: "The class 'Object' can't extend any other class."
comment: |-
7.9 Superclasses: It is a compile-time error to specify an extends clause
for class Object.
OBSOLETE_COLON_FOR_DEFAULT_VALUE:
problemMessage: Using a colon as a separator before a default value is no longer supported.
correctionMessage: Try replacing the colon with an equal sign.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a colon is used as the
separator before the default value of an optional parameter. While this
syntax used to be allowed, it's deprecated in favor of using an equal
sign.
#### Example
The following code produces this diagnostic because a colon is being used
before the default value of the optional parameter `i`:
```dart
void f({int i [!:!] 0}) {}
```
#### Common fixes
Replace the colon with an equal sign:
```dart
void f({int i = 0}) {}
```
ON_REPEATED:
problemMessage: "The type '{0}' can be included in the superclass constraints only once."
correctionMessage: Try removing all except one occurrence of the type name.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the interface that is implemented more than once
documentation: |-
#### Description
The analyzer produces this diagnostic when the same type is listed in the
superclass constraints of a mixin multiple times.
#### Example
The following code produces this diagnostic because `A` is included twice
in the superclass constraints for `M`:
```dart
mixin M on A, [!A!] {
}
class A {}
class B {}
```
#### Common fixes
If a different type should be included in the superclass constraints, then
replace one of the occurrences with the other type:
```dart
mixin M on A, B {
}
class A {}
class B {}
```
If no other type was intended, then remove the repeated type name:
```dart
mixin M on A {
}
class A {}
class B {}
```
OPTIONAL_PARAMETER_IN_OPERATOR:
problemMessage: "Optional parameters aren't allowed when defining an operator."
correctionMessage: Try removing the optional parameters.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when one or more of the parameters in
an operator declaration are optional.
#### Example
The following code produces this diagnostic because the parameter `other`
is an optional parameter:
```dart
class C {
C operator +([[!C? other!]]) => this;
}
```
#### Common fixes
Make all of the parameters be required parameters:
```dart
class C {
C operator +(C other) => this;
}
```
PART_OF_DIFFERENT_LIBRARY:
problemMessage: "Expected this library to be part of '{0}', not '{1}'."
correctionMessage: "Try including a different part, or changing the name of the library in the part's part-of directive."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of expected library name
1: the non-matching actual library name from the "part of" declaration
documentation: |-
#### Description
The analyzer produces this diagnostic when a library attempts to include a
file as a part of itself when the other file is a part of a different
library.
#### Example
Given a file `part.dart` containing
```dart
%uri="package:a/part.dart"
part of 'library.dart';
```
The following code, in any file other than `library.dart`, produces this
diagnostic because it attempts to include `part.dart` as a part of itself
when `part.dart` is a part of a different library:
```dart
part [!'package:a/part.dart'!];
```
#### Common fixes
If the library should be using a different file as a part, then change the
URI in the part directive to be the URI of the other file.
If the [part file][] should be a part of this library, then update the URI
(or library name) in the part-of directive to be the URI (or name) of the
correct library.
PART_OF_NON_PART:
problemMessage: "The included part '{0}' must have a part-of directive."
correctionMessage: "Try adding a part-of directive to '{0}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the URI pointing to a non-library declaration
documentation: |-
#### Description
The analyzer produces this diagnostic when a part directive is found and
the referenced file doesn't have a part-of directive.
#### Example
Given a file `a.dart` containing:
```dart
%uri="lib/a.dart"
class A {}
```
The following code produces this diagnostic because `a.dart` doesn't
contain a part-of directive:
```dart
part [!'a.dart'!];
```
#### Common fixes
If the referenced file is intended to be a part of another library, then
add a part-of directive to the file:
```dart
part of 'test.dart';
class A {}
```
If the referenced file is intended to be a library, then replace the part
directive with an import directive:
```dart
import 'a.dart';
```
PART_OF_UNNAMED_LIBRARY:
problemMessage: "The library is unnamed. A URI is expected, not a library name '{0}', in the part-of directive."
correctionMessage: Try changing the part-of directive to a URI, or try including a different part.
hasPublishedDocs: true
comment: |-
Parameters:
0: the non-matching actual library name from the "part of" declaration
documentation: |-
#### Description
The analyzer produces this diagnostic when a library that doesn't have a
`library` directive (and hence has no name) contains a `part` directive
and the `part of` directive in the [part file][] uses a name to specify
the library that it's a part of.
#### Example
Given a [part file][] named `part_file.dart` containing the following
code:
```dart
%uri="lib/part_file.dart"
part of lib;
```
The following code produces this diagnostic because the library including
the [part file][] doesn't have a name even though the [part file][] uses a
name to specify which library it's a part of:
```dart
part [!'part_file.dart'!];
```
#### Common fixes
Change the `part of` directive in the [part file][] to specify its library
by URI:
```dart
%uri="lib/part_file.dart"
part of 'test.dart';
```
PATTERN_ASSIGNMENT_NOT_LOCAL_VARIABLE:
problemMessage: Only local variables can be assigned in pattern assignments.
correctionMessage: Try assigning to a local variable.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a pattern assignment assigns a
value to anything other than a local variable. Patterns can't assign to
fields or top-level variables.
#### Example
If the code is cleaner when destructuring with a pattern, then rewrite the
code to assign the value to a local variable in a pattern declaration,
assigning the non-local variable separately:
```dart
class C {
var x = 0;
void f((int, int) r) {
([!x!], _) = r;
}
}
```
#### Common fixes
If the code is cleaner when using a pattern assignment, then rewrite the
code to assign the value to a local variable, assigning the non-local
variable separately:
```dart
class C {
var x = 0;
void f((int, int) r) {
var (a, _) = r;
x = a;
}
}
```
If the code is cleaner without using a pattern assignment, then rewrite
the code to not use a pattern assignment:
```dart
class C {
var x = 0;
void f((int, int) r) {
x = r.$1;
}
}
```
PATTERN_TYPE_MISMATCH_IN_IRREFUTABLE_CONTEXT:
problemMessage: "The matched value of type '{0}' isn't assignable to the required type '{1}'."
correctionMessage: "Try changing the required type of the pattern, or the matched value type."
hasPublishedDocs: true
comment: |-
Parameters:
0: the matched type
1: the required type
documentation: |-
#### Description
The analyzer produces this diagnostic when the type of the value on the
right-hand side of a pattern assignment or pattern declaration doesn't
match the type required by the pattern being used to match it.
#### Example
The following code produces this diagnostic because `x` might not be a
`String` and hence might not match the object pattern:
```dart
void f(Object x) {
var [!String(length: a)!] = x;
print(a);
}
```
#### Common fixes
Change the code so that the type of the expression on the right-hand side
matches the type required by the pattern:
```dart
void f(String x) {
var String(length: a) = x;
print(a);
}
```
PATTERN_VARIABLE_ASSIGNMENT_INSIDE_GUARD:
problemMessage: Pattern variables can't be assigned inside the guard of the enclosing guarded pattern.
correctionMessage: Try assigning to a different variable.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a pattern variable is assigned
a value inside a guard (`when`) clause.
#### Example
The following code produces this diagnostic because the variable `a` is
assigned a value inside the guard clause:
```dart
void f(int x) {
if (x case var a when ([!a!] = 1) > 0) {
print(a);
}
}
```
#### Common fixes
If there's a value you need to capture, then assign it to a different
variable:
```dart
void f(int x) {
var b;
if (x case var a when (b = 1) > 0) {
print(a + b);
}
}
```
If there isn't a value you need to capture, then remove the assignment:
```dart
void f(int x) {
if (x case var a when 1 > 0) {
print(a);
}
}
```
PATTERN_VARIABLE_SHARED_CASE_SCOPE_DIFFERENT_FINALITY_OR_TYPE:
sharedName: INVALID_PATTERN_VARIABLE_IN_SHARED_CASE_SCOPE
problemMessage: "The variable '{0}' doesn't have the same type and/or finality in all cases that share this body."
correctionMessage: Try declaring the variable pattern with the same type and finality in all cases.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the pattern variable
documentation: |-
#### Description
The analyzer produces this diagnostic when multiple case clauses in a
switch statement share a body, and at least one of them declares a
variable that is referenced in the shared statements, but the variable is
either not declared in all of the case clauses or it is declared in
inconsistent ways.
If the variable isn't declared in all of the case clauses, then it won't
have a value if one of the clauses that doesn't declare the variable is
the one that matches and executes the body. This includes the situation
where one of the case clauses is the `default` clause.
If the variable is declared in inconsistent ways, either being `final` in
some cases and not `final` in others or having a different type in
different cases, then the semantics of what the type or finality of the
variable should be are not defined.
#### Examples
The following code produces this diagnostic because the variable `a` is
only declared in one of the case clauses, and won't have a value if the
second clause is the one that matched `x`:
```dart
void f(Object? x) {
switch (x) {
case int a when a > 0:
case 0:
[!a!];
}
}
```
The following code produces this diagnostic because the variable `a` isn't
declared in the `default` clause, and won't have a value if the body is
executed because none of the other clauses matched `x`:
```dart
void f(Object? x) {
switch (x) {
case int a when a > 0:
default:
[!a!];
}
}
```
The following code produces this diagnostic because the variable `a` won't
have a value if the body is executed because a different group of cases
caused control to continue at the label:
```dart
void f(Object? x) {
switch (x) {
someLabel:
case int a when a > 0:
[!a!];
case int b when b < 0:
continue someLabel;
}
}
```
The following code produces this diagnostic because the variable `a`,
while being assigned in all of the case clauses, doesn't have then same
type associated with it in every clause:
```dart
void f(Object? x) {
switch (x) {
case int a when a < 0:
case num a when a > 0:
[!a!];
}
}
```
The following code produces this diagnostic because the variable `a` is
`final` in the first case clause and isn't `final` in the second case
clause:
```dart
void f(Object? x) {
switch (x) {
case final int a when a < 0:
case int a when a > 0:
[!a!];
}
}
```
#### Common fixes
If the variable isn't declared in all of the cases, and you need to
reference it in the statements, then declare it in the other cases:
```dart
void f(Object? x) {
switch (x) {
case int a when a > 0:
case int a when a == 0:
a;
}
}
```
If the variable isn't declared in all of the cases, and you don't need to
reference it in the statements, then remove the references to it and
remove the declarations from the other cases:
```dart
void f(int x) {
switch (x) {
case > 0:
case 0:
}
}
```
If the type of the variable is different, decide the type the variable
should have and make the cases consistent:
```dart
void f(Object? x) {
switch (x) {
case num a when a < 0:
case num a when a > 0:
a;
}
}
```
If the finality of the variable is different, decide whether it should be
`final` or not `final` and make the cases consistent:
```dart
void f(Object? x) {
switch (x) {
case final int a when a < 0:
case final int a when a > 0:
a;
}
}
```
PATTERN_VARIABLE_SHARED_CASE_SCOPE_HAS_LABEL:
sharedName: INVALID_PATTERN_VARIABLE_IN_SHARED_CASE_SCOPE
problemMessage: "The variable '{0}' is not available because there is a label or 'default' case."
correctionMessage: Try removing the label, or providing the 'default' case with its own body.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the pattern variable
PATTERN_VARIABLE_SHARED_CASE_SCOPE_NOT_ALL_CASES:
sharedName: INVALID_PATTERN_VARIABLE_IN_SHARED_CASE_SCOPE
problemMessage: "The variable '{0}' is available in some, but not all cases that share this body."
correctionMessage: Try declaring the variable pattern with the same type and finality in all cases.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the pattern variable
POSITIONAL_FIELD_IN_OBJECT_PATTERN:
problemMessage: Object patterns can only use named fields.
correctionMessage: Try specifying the field name.
comment: No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when an object pattern contains a
field without specifying the getter name. Object pattern fields match
against values that the object's getters return. Without a getter name
specified, the pattern field can't access a value to attempt to match against.
#### Example
The following code produces this diagnostic because the object pattern
`String(1)` doesn't specify which getter of `String` to access and compare
with the value `1`:
```dart
void f(Object o) {
if (o case String([!1!])) {}
}
```
#### Common fixes
Add the getter name to access the value, followed
by a colon before the pattern to match against:
```dart
void f(Object o) {
if (o case String(length: 1)) {}
}
```
POSITIONAL_SUPER_FORMAL_PARAMETER_WITH_POSITIONAL_ARGUMENT:
problemMessage: Positional super parameters can't be used when the super constructor invocation has a positional argument.
correctionMessage: Try making all the positional parameters passed to the super constructor be either all super parameters or all normal parameters.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when some, but not all, of the
positional parameters provided to the constructor of the superclass are
using a super parameter.
Positional super parameters are associated with positional parameters in
the super constructor by their index. That is, the first super parameter
is associated with the first positional parameter in the super
constructor, the second with the second, and so on. The same is true for
positional arguments. Having both positional super parameters and
positional arguments means that there are two values associated with the
same parameter in the superclass's constructor, and hence isn't allowed.
#### Example
The following code produces this diagnostic because the constructor
`B.new` is using a super parameter to pass one of the required positional
parameters to the super constructor in `A`, but is explicitly passing the
other in the super constructor invocation:
```dart
class A {
A(int x, int y);
}
class B extends A {
B(int x, super.[!y!]) : super(x);
}
```
#### Common fixes
If all the positional parameters can be super parameters, then convert the
normal positional parameters to be super parameters:
```dart
class A {
A(int x, int y);
}
class B extends A {
B(super.x, super.y);
}
```
If some positional parameters can't be super parameters, then convert the
super parameters to be normal parameters:
```dart
class A {
A(int x, int y);
}
class B extends A {
B(int x, int y) : super(x, y);
}
```
PREFIX_COLLIDES_WITH_TOP_LEVEL_MEMBER:
problemMessage: "The name '{0}' is already used as an import prefix and can't be used to name a top-level element."
correctionMessage: Try renaming either the top-level element or the prefix.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the prefix
documentation: |-
#### Description
The analyzer produces this diagnostic when a name is used as both an import
prefix and the name of a top-level declaration in the same library.
#### Example
The following code produces this diagnostic because `f` is used as both an
import prefix and the name of a function:
```dart
import 'dart:math' as f;
int [!f!]() => f.min(0, 1);
```
#### Common fixes
If you want to use the name for the import prefix, then rename the
top-level declaration:
```dart
import 'dart:math' as f;
int g() => f.min(0, 1);
```
If you want to use the name for the top-level declaration, then rename the
import prefix:
```dart
import 'dart:math' as math;
int f() => math.min(0, 1);
```
PREFIX_IDENTIFIER_NOT_FOLLOWED_BY_DOT:
problemMessage: "The name '{0}' refers to an import prefix, so it must be followed by '.'."
correctionMessage: Try correcting the name to refer to something other than a prefix, or renaming the prefix.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the prefix
documentation: |-
#### Description
The analyzer produces this diagnostic when an import prefix is used by
itself, without accessing any of the names declared in the libraries
associated with the prefix. Prefixes aren't variables, and therefore can't
be used as a value.
#### Example
The following code produces this diagnostic because the prefix `math` is
being used as if it were a variable:
```dart
import 'dart:math' as math;
void f() {
print([!math!]);
}
```
#### Common fixes
If the code is incomplete, then reference something in one of the libraries
associated with the prefix:
```dart
import 'dart:math' as math;
void f() {
print(math.pi);
}
```
If the name is wrong, then correct the name.
PREFIX_SHADOWED_BY_LOCAL_DECLARATION:
problemMessage: "The prefix '{0}' can't be used here because it's shadowed by a local declaration."
correctionMessage: Try renaming either the prefix or the local declaration.
comment: |-
Parameters:
0: the prefix being shadowed
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when an import prefix is used in a
context where it isn't visible because it was shadowed by a local
declaration.
#### Example
The following code produces this diagnostic because the prefix `a` is
being used to access the class `Future`, but isn't visible because it's
shadowed by the parameter `a`:
```dart
import 'dart:async' as a;
a.Future? f(int a) {
[!a!].Future? x;
return x;
}
```
#### Common fixes
Rename either the prefix:
```dart
import 'dart:async' as p;
p.Future? f(int a) {
p.Future? x;
return x;
}
```
Or rename the local variable:
```dart
import 'dart:async' as a;
a.Future? f(int p) {
a.Future? x;
return x;
}
```
PRIVATE_COLLISION_IN_MIXIN_APPLICATION:
problemMessage: "The private name '{0}', defined by '{1}', conflicts with the same name defined by '{2}'."
correctionMessage: "Try removing '{1}' from the 'with' clause."
hasPublishedDocs: true
comment: |-
Parameters:
0: the private name that collides
1: the name of the first mixin
2: the name of the second mixin
documentation: |-
#### Description
The analyzer produces this diagnostic when two mixins that define the same
private member are used together in a single class in a library other than
the one that defines the mixins.
#### Example
Given a file `a.dart` containing the following code:
```dart
%uri="lib/a.dart"
mixin A {
void _foo() {}
}
mixin B {
void _foo() {}
}
```
The following code produces this diagnostic because the mixins `A` and `B`
both define the method `_foo`:
```dart
import 'a.dart';
class C extends Object with A, [!B!] {}
```
#### Common fixes
If you don't need both of the mixins, then remove one of them from the
`with` clause:
```dart
import 'a.dart';
class C extends Object with A, [!B!] {}
```
If you need both of the mixins, then rename the conflicting member in one
of the two mixins.
PRIVATE_OPTIONAL_PARAMETER:
problemMessage: "Named parameters can't start with an underscore."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the name of a named parameter
starts with an underscore.
#### Example
The following code produces this diagnostic because the named parameter
`_x` starts with an underscore:
```dart
class C {
void m({int [!_x!] = 0}) {}
}
```
#### Common fixes
Rename the parameter so that it doesn't start with an underscore:
```dart
class C {
void m({int x = 0}) {}
}
```
PRIVATE_SETTER:
problemMessage: "The setter '{0}' is private and can't be accessed outside the library that declares it."
correctionMessage: Try making it public.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the setter
documentation: |-
#### Description
The analyzer produces this diagnostic when a private setter is used in a
library where it isn't visible.
#### Example
Given a file `a.dart` that contains the following:
```dart
%uri="lib/a.dart"
class A {
static int _f = 0;
}
```
The following code produces this diagnostic because it references the
private setter `_f` even though the setter isn't visible:
```dart
import 'a.dart';
void f() {
A.[!_f!] = 0;
}
```
#### Common fixes
If you're able to make the setter public, then do so:
```dart
%uri="lib/a.dart"
class A {
static int f = 0;
}
```
If you aren't able to make the setter public, then find a different way to
implement the code.
READ_POTENTIALLY_UNASSIGNED_FINAL:
problemMessage: "The final variable '{0}' can't be read because it's potentially unassigned at this point."
correctionMessage: Ensure that it is assigned on necessary execution paths.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the variable
documentation: |-
#### Description
The analyzer produces this diagnostic when a final local variable that
isn't initialized at the declaration site is read at a point where the
compiler can't prove that the variable is always initialized before it's
referenced.
#### Example
The following code produces this diagnostic because the final local
variable `x` is read (on line 3) when it's possible that it hasn't yet
been initialized:
```dart
int f() {
final int x;
return [!x!];
}
```
#### Common fixes
Ensure that the variable has been initialized before it's read:
```dart
int f(bool b) {
final int x;
if (b) {
x = 0;
} else {
x = 1;
}
return x;
}
```
RECURSIVE_COMPILE_TIME_CONSTANT:
problemMessage: The compile-time constant expression depends on itself.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the value of a compile-time
constant is defined in terms of itself, either directly or indirectly,
creating an infinite loop.
#### Example
The following code produces this diagnostic twice because both of the
constants are defined in terms of the other:
```dart
const [!secondsPerHour!] = minutesPerHour * 60;
const [!minutesPerHour!] = secondsPerHour / 60;
```
#### Common fixes
Break the cycle by finding an alternative way of defining at least one of
the constants:
```dart
const secondsPerHour = minutesPerHour * 60;
const minutesPerHour = 60;
```
RECURSIVE_CONSTRUCTOR_REDIRECT:
problemMessage: "Constructors can't redirect to themselves either directly or indirectly."
correctionMessage: Try changing one of the constructors in the loop to not redirect.
hasPublishedDocs: true
comment: |-
No parameters.
TODO(scheglov) review this later, there are no explicit "it is a
compile-time error" in specification. But it was added to the co19 and
there is same error for factories.
https://code.google.com/p/dart/issues/detail?id=954
documentation: |-
#### Description
The analyzer produces this diagnostic when a constructor redirects to
itself, either directly or indirectly, creating an infinite loop.
#### Examples
The following code produces this diagnostic because the generative
constructors `C.a` and `C.b` each redirect to the other:
```dart
class C {
C.a() : [!this.b()!];
C.b() : [!this.a()!];
}
```
The following code produces this diagnostic because the factory
constructors `A` and `B` each redirect to the other:
```dart
abstract class A {
factory A() = [!B!];
}
class B implements A {
factory B() = [!A!];
B.named();
}
```
#### Common fixes
In the case of generative constructors, break the cycle by finding defining
at least one of the constructors to not redirect to another constructor:
```dart
class C {
C.a() : this.b();
C.b();
}
```
In the case of factory constructors, break the cycle by defining at least
one of the factory constructors to do one of the following:
- Redirect to a generative constructor:
```dart
abstract class A {
factory A() = B;
}
class B implements A {
factory B() = B.named;
B.named();
}
```
- Not redirect to another constructor:
```dart
abstract class A {
factory A() = B;
}
class B implements A {
factory B() {
return B.named();
}
B.named();
}
```
- Not be a factory constructor:
```dart
abstract class A {
factory A() = B;
}
class B implements A {
B();
B.named();
}
```
RECURSIVE_FACTORY_REDIRECT:
sharedName: RECURSIVE_CONSTRUCTOR_REDIRECT
problemMessage: "Constructors can't redirect to themselves either directly or indirectly."
correctionMessage: Try changing one of the constructors in the loop to not redirect.
hasPublishedDocs: true
comment: No parameters.
RECURSIVE_INTERFACE_INHERITANCE:
problemMessage: "'{0}' can't be a superinterface of itself: {1}."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the class that implements itself recursively
1: a string representation of the implements loop
documentation: |-
#### Description
The analyzer produces this diagnostic when there's a circularity in the
type hierarchy. This happens when a type, either directly or indirectly,
is declared to be a subtype of itself.
#### Example
The following code produces this diagnostic because the class `A` is
declared to be a subtype of `B`, and `B` is a subtype of `A`:
```dart
class [!A!] extends B {}
class B implements A {}
```
#### Common fixes
Change the type hierarchy so that there's no circularity.
RECURSIVE_INTERFACE_INHERITANCE_EXTENDS:
sharedName: RECURSIVE_INTERFACE_INHERITANCE
problemMessage: "'{0}' can't extend itself."
hasPublishedDocs: true
comment: |-
7.10 Superinterfaces: It is a compile-time error if the interface of a
class <i>C</i> is a superinterface of itself.
8.1 Superinterfaces: It is a compile-time error if an interface is a
superinterface of itself.
7.9 Superclasses: It is a compile-time error if a class <i>C</i> is a
superclass of itself.
Parameters:
0: the name of the class that implements itself recursively
RECURSIVE_INTERFACE_INHERITANCE_IMPLEMENTS:
sharedName: RECURSIVE_INTERFACE_INHERITANCE
problemMessage: "'{0}' can't implement itself."
hasPublishedDocs: true
comment: |-
7.10 Superinterfaces: It is a compile-time error if the interface of a
class <i>C</i> is a superinterface of itself.
8.1 Superinterfaces: It is a compile-time error if an interface is a
superinterface of itself.
7.9 Superclasses: It is a compile-time error if a class <i>C</i> is a
superclass of itself.
Parameters:
0: the name of the class that implements itself recursively
RECURSIVE_INTERFACE_INHERITANCE_ON:
sharedName: RECURSIVE_INTERFACE_INHERITANCE
problemMessage: "'{0}' can't use itself as a superclass constraint."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the mixin that constraints itself recursively
RECURSIVE_INTERFACE_INHERITANCE_WITH:
sharedName: RECURSIVE_INTERFACE_INHERITANCE
problemMessage: "'{0}' can't use itself as a mixin."
hasPublishedDocs: true
comment: |-
7.10 Superinterfaces: It is a compile-time error if the interface of a
class <i>C</i> is a superinterface of itself.
8.1 Superinterfaces: It is a compile-time error if an interface is a
superinterface of itself.
7.9 Superclasses: It is a compile-time error if a class <i>C</i> is a
superclass of itself.
Parameters:
0: the name of the class that implements itself recursively
REDIRECT_GENERATIVE_TO_MISSING_CONSTRUCTOR:
problemMessage: "The constructor '{0}' couldn't be found in '{1}'."
correctionMessage: "Try redirecting to a different constructor, or defining the constructor named '{0}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the constructor
1: the name of the class
documentation: |-
#### Description
The analyzer produces this diagnostic when a generative constructor
redirects to a constructor that isn't defined.
#### Example
The following code produces this diagnostic because the constructor `C.a`
redirects to the constructor `C.b`, but `C.b` isn't defined:
```dart
class C {
C.a() : [!this.b()!];
}
```
#### Common fixes
If the missing constructor must be called, then define it:
```dart
class C {
C.a() : this.b();
C.b();
}
```
If the missing constructor doesn't need to be called, then remove the
redirect:
```dart
class C {
C.a();
}
```
REDIRECT_GENERATIVE_TO_NON_GENERATIVE_CONSTRUCTOR:
problemMessage: "Generative constructors can't redirect to a factory constructor."
correctionMessage: Try redirecting to a different constructor.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a generative constructor
redirects to a factory constructor.
#### Example
The following code produces this diagnostic because the generative
constructor `C.a` redirects to the factory constructor `C.b`:
```dart
class C {
C.a() : [!this.b()!];
factory C.b() => C.a();
}
```
#### Common fixes
If the generative constructor doesn't need to redirect to another
constructor, then remove the redirect.
```dart
class C {
C.a();
factory C.b() => C.a();
}
```
If the generative constructor must redirect to another constructor, then
make the other constructor be a generative (non-factory) constructor:
```dart
class C {
C.a() : this.b();
C.b();
}
```
REDIRECT_TO_ABSTRACT_CLASS_CONSTRUCTOR:
problemMessage: "The redirecting constructor '{0}' can't redirect to a constructor of the abstract class '{1}'."
correctionMessage: Try redirecting to a constructor of a different class.
comment: |-
Parameters:
0: the name of the redirecting constructor
1: the name of the abstract class defining the constructor being redirected to
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a constructor redirects to a
constructor in an abstract class.
#### Example
The following code produces this diagnostic because the factory
constructor in `A` redirects to a constructor in `B`, but `B` is an
abstract class:
```dart
class A {
factory A() = [!B!];
}
abstract class B implements A {}
```
#### Common fixes
If the code redirects to the correct constructor, then change the class so
that it isn't abstract:
```dart
class A {
factory A() = B;
}
class B implements A {}
```
Otherwise, change the factory constructor so that it either redirects to a
constructor in a concrete class, or has a concrete implementation.
REDIRECT_TO_INVALID_FUNCTION_TYPE:
problemMessage: "The redirected constructor '{0}' has incompatible parameters with '{1}'."
correctionMessage: Try redirecting to a different constructor.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the redirected constructor
1: the name of the redirecting constructor
documentation: |-
#### Description
The analyzer produces this diagnostic when a factory constructor attempts
to redirect to another constructor, but the two have incompatible
parameters. The parameters are compatible if all of the parameters of the
redirecting constructor can be passed to the other constructor and if the
other constructor doesn't require any parameters that aren't declared by
the redirecting constructor.
#### Examples
The following code produces this diagnostic because the constructor for `A`
doesn't declare a parameter that the constructor for `B` requires:
```dart
abstract class A {
factory A() = [!B!];
}
class B implements A {
B(int x);
B.zero();
}
```
The following code produces this diagnostic because the constructor for `A`
declares a named parameter (`y`) that the constructor for `B` doesn't
allow:
```dart
abstract class A {
factory A(int x, {int y}) = [!B!];
}
class B implements A {
B(int x);
}
```
#### Common fixes
If there's a different constructor that is compatible with the redirecting
constructor, then redirect to that constructor:
```dart
abstract class A {
factory A() = B.zero;
}
class B implements A {
B(int x);
B.zero();
}
```
Otherwise, update the redirecting constructor to be compatible:
```dart
abstract class A {
factory A(int x) = B;
}
class B implements A {
B(int x);
}
```
REDIRECT_TO_INVALID_RETURN_TYPE:
problemMessage: "The return type '{0}' of the redirected constructor isn't a subtype of '{1}'."
correctionMessage: Try redirecting to a different constructor.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the redirected constructor's return type
1: the name of the redirecting constructor's return type
documentation: |-
#### Description
The analyzer produces this diagnostic when a factory constructor redirects
to a constructor whose return type isn't a subtype of the type that the
factory constructor is declared to produce.
#### Example
The following code produces this diagnostic because `A` isn't a subclass
of `C`, which means that the value returned by the constructor `A()`
couldn't be returned from the constructor `C()`:
```dart
class A {}
class B implements C {}
class C {
factory C() = [!A!];
}
```
#### Common fixes
If the factory constructor is redirecting to a constructor in the wrong
class, then update the factory constructor to redirect to the correct
constructor:
```dart
class A {}
class B implements C {}
class C {
factory C() = B;
}
```
If the class defining the constructor being redirected to is the class that
should be returned, then make it a subtype of the factory's return type:
```dart
class A implements C {}
class B implements C {}
class C {
factory C() = A;
}
```
REDIRECT_TO_MISSING_CONSTRUCTOR:
problemMessage: "The constructor '{0}' couldn't be found in '{1}'."
correctionMessage: "Try redirecting to a different constructor, or define the constructor named '{0}'."
comment: |-
Parameters:
0: the name of the constructor
1: the name of the class containing the constructor
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a constructor redirects to a
constructor that doesn't exist.
#### Example
The following code produces this diagnostic because the factory
constructor in `A` redirects to a constructor in `B` that doesn't exist:
```dart
class A {
factory A() = [!B.name!];
}
class B implements A {
B();
}
```
#### Common fixes
If the constructor being redirected to is correct, then define the
constructor:
```dart
class A {
factory A() = B.name;
}
class B implements A {
B();
B.name();
}
```
If a different constructor should be invoked, then update the redirect:
```dart
class A {
factory A() = B;
}
class B implements A {
B();
}
```
REDIRECT_TO_NON_CLASS:
problemMessage: "The name '{0}' isn't a type and can't be used in a redirected constructor."
correctionMessage: Try redirecting to a different constructor.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the non-type referenced in the redirect
documentation: |-
#### Description
One way to implement a factory constructor is to redirect to another
constructor by referencing the name of the constructor. The analyzer
produces this diagnostic when the redirect is to something other than a
constructor.
#### Example
The following code produces this diagnostic because `f` is a function:
```dart
C f() => throw 0;
class C {
factory C() = [!f!];
}
```
#### Common fixes
If the constructor isn't defined, then either define it or replace it with
a constructor that is defined.
If the constructor is defined but the class that defines it isn't visible,
then you probably need to add an import.
If you're trying to return the value returned by a function, then rewrite
the constructor to return the value from the constructor's body:
```dart
C f() => throw 0;
class C {
factory C() => f();
}
```
REDIRECT_TO_NON_CONST_CONSTRUCTOR:
problemMessage: "A constant redirecting constructor can't redirect to a non-constant constructor."
correctionMessage: Try redirecting to a different constructor.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a constructor marked as `const`
redirects to a constructor that isn't marked as `const`.
#### Example
The following code produces this diagnostic because the constructor `C.a`
is marked as `const` but redirects to the constructor `C.b`, which isn't:
```dart
class C {
const C.a() : this.[!b!]();
C.b();
}
```
#### Common fixes
If the non-constant constructor can be marked as `const`, then mark it as
`const`:
```dart
class C {
const C.a() : this.b();
const C.b();
}
```
If the non-constant constructor can't be marked as `const`, then either
remove the redirect or remove `const` from the redirecting constructor:
```dart
class C {
C.a() : this.b();
C.b();
}
```
REDIRECT_TO_TYPE_ALIAS_EXPANDS_TO_TYPE_PARAMETER:
problemMessage: "A redirecting constructor can't redirect to a type alias that expands to a type parameter."
correctionMessage: Try replacing it with a class.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a redirecting factory
constructor redirects to a type alias, and the type alias expands to one of
the type parameters of the type alias. This isn't allowed because the value
of the type parameter is a type rather than a class.
#### Example
The following code produces this diagnostic because the redirect to `B<A>`
is to a type alias whose value is `T`, even though it looks like the value
should be `A`:
```dart
class A implements C {}
typedef B<T> = T;
abstract class C {
factory C() = [!B!]<A>;
}
```
#### Common fixes
Use either a class name or a type alias that is defined to be a class
rather than a type alias defined to be a type parameter:
```dart
class A implements C {}
abstract class C {
factory C() = A;
}
```
REFERENCED_BEFORE_DECLARATION:
problemMessage: "Local variable '{0}' can't be referenced before it is declared."
correctionMessage: "Try moving the declaration to before the first use, or renaming the local variable so that it doesn't hide a name from an enclosing scope."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the variable
documentation: |-
#### Description
The analyzer produces this diagnostic when a variable is referenced before
it's declared. In Dart, variables are visible everywhere in the block in
which they are declared, but can only be referenced after they are
declared.
The analyzer also produces a context message that indicates where the
declaration is located.
#### Example
The following code produces this diagnostic because `i` is used before it
is declared:
```dart
%language=2.9
void f() {
print([!i!]);
int i = 5;
}
```
#### Common fixes
If you intended to reference the local variable, move the declaration
before the first reference:
```dart
%language=2.9
void f() {
int i = 5;
print(i);
}
```
If you intended to reference a name from an outer scope, such as a
parameter, instance field or top-level variable, then rename the local
declaration so that it doesn't hide the outer variable.
```dart
%language=2.9
void f(int i) {
print(i);
int x = 5;
print(x);
}
```
REFUTABLE_PATTERN_IN_IRREFUTABLE_CONTEXT:
problemMessage: Refutable patterns can't be used in an irrefutable context.
correctionMessage: Try using an if-case, a 'switch' statement, or a 'switch' expression instead.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a [refutable pattern][] is used
in a context where only an [irrefutable pattern][] is allowed.
The refutable patterns that are disallowed are:
- logical-or
- relational
- null-check
- constant
The contexts that are checked are:
- pattern-based variable declarations
- pattern-based for loops
- assignments with a pattern on the left-hand side
#### Example
The following code produces this diagnostic because the null-check
pattern, which is a refutable pattern, is in a pattern-based variable
declaration, which doesn't allow refutable patterns:
```dart
void f(int? x) {
var ([!_?!]) = x;
}
```
#### Common fixes
Rewrite the code to not use a refutable pattern in an irrefutable context.
RELATIONAL_PATTERN_OPERAND_TYPE_NOT_ASSIGNABLE:
problemMessage: "The constant expression type '{0}' is not assignable to the parameter type '{1}' of the '{2}' operator."
hasPublishedDocs: true
comment: |-
Parameters:
0: the operand type
1: the parameter type of the invoked operator
2: the name of the invoked operator
documentation: |-
#### Description
The analyzer produces this diagnostic when the operand of a relational
pattern has a type that isn't assignable to the parameter of the operator
that will be invoked.
#### Example
The following code produces this diagnostic because the operand in the
relational pattern (`0`) is an `int`, but the `>` operator defined in `C`
expects an object of type `C`:
```dart
class C {
const C();
bool operator >(C other) => true;
}
void f(C c) {
switch (c) {
case > [!0!]:
print('positive');
}
}
```
#### Common fixes
If the switch is using the correct value, then change the case to compare
the value to the right type of object:
```dart
class C {
const C();
bool operator >(C other) => true;
}
void f(C c) {
switch (c) {
case > const C():
print('positive');
}
}
```
If the switch is using the wrong value, then change the expression used to
compute the value being matched:
```dart
class C {
const C();
bool operator >(C other) => true;
int get toInt => 0;
}
void f(C c) {
switch (c.toInt) {
case > 0:
print('positive');
}
}
```
RELATIONAL_PATTERN_OPERATOR_RETURN_TYPE_NOT_ASSIGNABLE_TO_BOOL:
problemMessage: The return type of operators used in relational patterns must be assignable to 'bool'.
correctionMessage: Try updating the operator declaration to return 'bool'.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a relational pattern references
an operator that doesn't produce a value of type `bool`.
#### Example
The following code produces this diagnostic because the operator `>`, used
in the relational pattern `> c2`, returns a value of type `int` rather
than a `bool`:
```dart
class C {
const C();
int operator >(C c) => 3;
bool operator <(C c) => false;
}
const C c2 = C();
void f(C c1) {
if (c1 case [!>!] c2) {}
}
```
#### Common fixes
If there's a different operator that should be used, then change the
operator:
```dart
class C {
const C();
int operator >(C c) => 3;
bool operator <(C c) => false;
}
const C c2 = C();
void f(C c1) {
if (c1 case < c2) {}
}
```
If the operator is expected to return `bool`, then update the declaration
of the operator:
```dart
class C {
const C();
bool operator >(C c) => true;
bool operator <(C c) => false;
}
const C c2 = C();
void f(C c1) {
if (c1 case > c2) {}
}
```
REST_ELEMENT_IN_MAP_PATTERN:
problemMessage: A map pattern can't contain a rest pattern.
correctionMessage: Try removing the rest pattern.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a map pattern contains a rest
pattern. Map patterns match a map with more keys
than those explicitly given in the pattern (as long as the given keys match),
so a rest pattern is unnecessary.
#### Example
The following code produces this diagnostic because the map pattern contains
a rest pattern:
```dart
void f(Map<int, String> x) {
if (x case {0: _, [!...!]}) {}
}
```
#### Common fixes
Remove the rest pattern:
```dart
void f(Map<int, String> x) {
if (x case {0: _}) {}
}
```
RETHROW_OUTSIDE_CATCH:
problemMessage: A rethrow must be inside of a catch clause.
correctionMessage: "Try moving the expression into a catch clause, or using a 'throw' expression."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a `rethrow` statement is outside
a `catch` clause. The `rethrow` statement is used to throw a caught
exception again, but there's no caught exception outside of a `catch`
clause.
#### Example
The following code produces this diagnostic because the`rethrow` statement
is outside of a `catch` clause:
```dart
void f() {
[!rethrow!];
}
```
#### Common fixes
If you're trying to rethrow an exception, then wrap the `rethrow` statement
in a `catch` clause:
```dart
void f() {
try {
// ...
} catch (exception) {
rethrow;
}
}
```
If you're trying to throw a new exception, then replace the `rethrow`
statement with a `throw` expression:
```dart
void f() {
throw UnsupportedError('Not yet implemented');
}
```
RETURN_IN_GENERATIVE_CONSTRUCTOR:
problemMessage: "Constructors can't return values."
correctionMessage: Try removing the return statement or using a factory constructor.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a generative constructor
contains a `return` statement that specifies a value to be returned.
Generative constructors always return the object that was created, and
therefore can't return a different object.
#### Example
The following code produces this diagnostic because the `return` statement
has an expression:
```dart
class C {
C() {
return [!this!];
}
}
```
#### Common fixes
If the constructor should create a new instance, then remove either the
`return` statement or the expression:
```dart
class C {
C();
}
```
If the constructor shouldn't create a new instance, then convert it to be a
factory constructor:
```dart
class C {
factory C() {
return _instance;
}
static C _instance = C._();
C._();
}
```
RETURN_IN_GENERATOR:
problemMessage: "Can't return a value from a generator function that uses the 'async*' or 'sync*' modifier."
correctionMessage: "Try replacing 'return' with 'yield', using a block function body, or changing the method body modifier."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a generator function (one whose
body is marked with either `async*` or `sync*`) uses either a `return`
statement to return a value or implicitly returns a value because of using
`=>`. In any of these cases, they should use `yield` instead of `return`.
#### Examples
The following code produces this diagnostic because the method `f` is a
generator and is using `return` to return a value:
```dart
Iterable<int> f() sync* {
[!return 3!];
}
```
The following code produces this diagnostic because the function `f` is a
generator and is implicitly returning a value:
```dart
Stream<int> f() async* [!=>!] 3;
```
#### Common fixes
If the function is using `=>` for the body of the function, then convert it
to a block function body, and use `yield` to return a value:
```dart
Stream<int> f() async* {
yield 3;
}
```
If the method is intended to be a generator, then use `yield` to return a
value:
```dart
Iterable<int> f() sync* {
yield 3;
}
```
If the method isn't intended to be a generator, then remove the modifier
from the body (or use `async` if you're returning a future):
```dart
int f() {
return 3;
}
```
RETURN_OF_INVALID_TYPE_FROM_CONSTRUCTOR:
sharedName: RETURN_OF_INVALID_TYPE
problemMessage: "A value of type '{0}' can't be returned from the constructor '{2}' because it has a return type of '{1}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the return type as declared in the return statement
1: the expected return type as defined by the enclosing class
2: the name of the constructor
RETURN_OF_INVALID_TYPE_FROM_FUNCTION:
sharedName: RETURN_OF_INVALID_TYPE
problemMessage: "A value of type '{0}' can't be returned from the function '{2}' because it has a return type of '{1}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the return type as declared in the return statement
1: the expected return type as defined by the method
2: the name of the method
documentation: |-
#### Description
The analyzer produces this diagnostic when a method or function returns a
value whose type isn't assignable to the declared return type.
#### Example
The following code produces this diagnostic because `f` has a return type
of `String` but is returning an `int`:
```dart
String f() => [!3!];
```
#### Common fixes
If the return type is correct, then replace the value being returned with a
value of the correct type, possibly by converting the existing value:
```dart
String f() => 3.toString();
```
If the value is correct, then change the return type to match:
```dart
int f() => 3;
```
RETURN_OF_INVALID_TYPE_FROM_METHOD:
sharedName: RETURN_OF_INVALID_TYPE
problemMessage: "A value of type '{0}' can't be returned from the method '{2}' because it has a return type of '{1}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the return type as declared in the return statement
1: the expected return type as defined by the method
2: the name of the method
RETURN_OF_INVALID_TYPE_FROM_CLOSURE:
problemMessage: "The return type '{0}' isn't a '{1}', as required by the closure's context."
hasPublishedDocs: true
comment: |-
Parameters:
0: the return type as declared in the return statement
1: the expected return type as defined by the method
documentation: |-
#### Description
The analyzer produces this diagnostic when the static type of a returned
expression isn't assignable to the return type that the closure is required
to have.
#### Example
The following code produces this diagnostic because `f` is defined to be a
function that returns a `String`, but the closure assigned to it returns an
`int`:
```dart
String Function(String) f = (s) => [!3!];
```
#### Common fixes
If the return type is correct, then replace the returned value with a value
of the correct type, possibly by converting the existing value:
```dart
String Function(String) f = (s) => 3.toString();
```
RETURN_WITHOUT_VALUE:
problemMessage: "The return value is missing after 'return'."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when it finds a `return` statement
without an expression in a function that declares a return type.
#### Example
The following code produces this diagnostic because the function `f` is
expected to return an `int`, but no value is being returned:
```dart
int f() {
[!return!];
}
```
#### Common fixes
Add an expression that computes the value to be returned:
```dart
int f() {
return 0;
}
```
SEALED_CLASS_SUBTYPE_OUTSIDE_OF_LIBRARY:
sharedName: INVALID_USE_OF_TYPE_OUTSIDE_LIBRARY
problemMessage: "The class '{0}' can't be extended, implemented, or mixed in outside of its library because it's a sealed class."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the sealed class being extended, implemented, or mixed in
SET_ELEMENT_TYPE_NOT_ASSIGNABLE:
problemMessage: "The element type '{0}' can't be assigned to the set type '{1}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the actual type of the set element
1: the expected type of the set element
documentation: |-
#### Description
The analyzer produces this diagnostic when an element in a set literal has
a type that isn't assignable to the element type of the set.
#### Example
The following code produces this diagnostic because the type of the string
literal `'0'` is `String`, which isn't assignable to `int`, the element
type of the set:
```dart
var s = <int>{[!'0'!]};
```
#### Common fixes
If the element type of the set literal is wrong, then change the element
type of the set:
```dart
var s = <String>{'0'};
```
If the type of the element is wrong, then change the element:
```dart
var s = <int>{'0'.length};
```
SHARED_DEFERRED_PREFIX:
problemMessage: "The prefix of a deferred import can't be used in other import directives."
correctionMessage: Try renaming one of the prefixes.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a prefix in a deferred import is
also used as a prefix in other imports (whether deferred or not). The
prefix in a deferred import can't be shared with other imports because the
prefix is used to load the imported library.
#### Example
The following code produces this diagnostic because the prefix `x` is used
as the prefix for a deferred import and is also used for one other import:
```dart
import 'dart:math' [!deferred!] as x;
import 'dart:convert' as x;
var y = x.json.encode(x.min(0, 1));
```
#### Common fixes
If you can use a different name for the deferred import, then do so:
```dart
import 'dart:math' deferred as math;
import 'dart:convert' as x;
var y = x.json.encode(math.min(0, 1));
```
If you can use a different name for the other imports, then do so:
```dart
import 'dart:math' deferred as x;
import 'dart:convert' as convert;
var y = convert.json.encode(x.min(0, 1));
```
SPREAD_EXPRESSION_FROM_DEFERRED_LIBRARY:
problemMessage: "Constant values from a deferred library can't be spread into a const literal."
correctionMessage: Try making the deferred import non-deferred.
STATIC_ACCESS_TO_INSTANCE_MEMBER:
problemMessage: "Instance member '{0}' can't be accessed using static access."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the instance member
documentation: |-
#### Description
The analyzer produces this diagnostic when a class name is used to access
an instance field. Instance fields don't exist on a class; they exist only
on an instance of the class.
#### Example
The following code produces this diagnostic because `x` is an instance
field:
```dart
%language=2.9
class C {
static int a;
int b;
}
int f() => C.[!b!];
```
#### Common fixes
If you intend to access a static field, then change the name of the field
to an existing static field:
```dart
%language=2.9
class C {
static int a;
int b;
}
int f() => C.a;
```
If you intend to access the instance field, then use an instance of the
class to access the field:
```dart
%language=2.9
class C {
static int a;
int b;
}
int f(C c) => c.b;
```
SUBTYPE_OF_BASE_IS_NOT_BASE_FINAL_OR_SEALED:
sharedName: SUBTYPE_OF_BASE_OR_FINAL_IS_NOT_BASE_FINAL_OR_SEALED
problemMessage: "The type '{0}' must be 'base', 'final' or 'sealed' because the supertype '{1}' is 'base'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the subtype that is not 'base', 'final', or 'sealed'
1: the name of the 'base' supertype
documentation: |-
#### Description
The analyzer produces this diagnostic when a class or mixin has a direct
or indirect supertype that is either `base` or `final`, but the class or
mixin itself isn't marked either `base`, `final`, or `sealed`.
#### Example
The following code produces this diagnostic because the class `B` is a
subtype of `A`, and `A` is a `base` class, but `B` is neither `base`,
`final` or `sealed`:
```dart
base class A {}
class [!B!] extends A {}
```
#### Common fixes
Add either `base`, `final` or `sealed` to the class or mixin declaration:
```dart
base class A {}
final class B extends A {}
```
SUBTYPE_OF_FINAL_IS_NOT_BASE_FINAL_OR_SEALED:
sharedName: SUBTYPE_OF_BASE_OR_FINAL_IS_NOT_BASE_FINAL_OR_SEALED
problemMessage: "The type '{0}' must be 'base', 'final' or 'sealed' because the supertype '{1}' is 'final'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the subtype that is not 'base', 'final', or 'sealed'
1: the name of the 'final' supertype
SUPER_FORMAL_PARAMETER_TYPE_IS_NOT_SUBTYPE_OF_ASSOCIATED:
problemMessage: The type '{0}' of this parameter isn't a subtype of the type '{1}' of the associated super constructor parameter.
correctionMessage: Try removing the explicit type annotation from the parameter.
hasPublishedDocs: true
comment: |-
Parameters:
0: the type of super-parameter
1: the type of associated super-constructor parameter
documentation: |-
#### Description
The analyzer produces this diagnostic when the type of a super parameter
isn't a subtype of the corresponding parameter from the super constructor.
#### Example
The following code produces this diagnostic because the type of the super
parameter `x` in the constructor for `B` isn't a subtype of the parameter
`x` in the constructor for `A`:
```dart
class A {
A(num x);
}
class B extends A {
B(String super.[!x!]);
}
```
#### Common fixes
If the type of the super parameter can be the same as the parameter from
the super constructor, then remove the type annotation from the super
parameter (if the type is implicit, it is inferred from the type in the
super constructor):
```dart
class A {
A(num x);
}
class B extends A {
B(super.x);
}
```
If the type of the super parameter can be a subtype of the corresponding
parameter's type, then change the type of the super parameter:
```dart
class A {
A(num x);
}
class B extends A {
B(int super.x);
}
```
If the type of the super parameter can't be changed, then use a normal
parameter instead of a super parameter:
```dart
class A {
A(num x);
}
class B extends A {
B(String x) : super(x.length);
}
```
SUPER_FORMAL_PARAMETER_WITHOUT_ASSOCIATED_NAMED:
problemMessage: No associated named super constructor parameter.
correctionMessage: Try changing the name to the name of an existing named super constructor parameter, or creating such named parameter.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when there's a named super parameter
in a constructor and the implicitly or explicitly invoked super
constructor doesn't have a named parameter with the same name.
Named super parameters are associated by name with named parameters in the
super constructor.
#### Example
The following code produces this diagnostic because the constructor in `A`
doesn't have a parameter named `y`:
```dart
class A {
A({int? x});
}
class B extends A {
B({super.[!y!]});
}
```
#### Common fixes
If the super parameter should be associated with an existing parameter
from the super constructor, then change the name to match the name of the
corresponding parameter:
```dart
class A {
A({int? x});
}
class B extends A {
B({super.x});
}
```
If the super parameter should be associated with a parameter that hasn't
yet been added to the super constructor, then add it:
```dart
class A {
A({int? x, int? y});
}
class B extends A {
B({super.y});
}
```
If the super parameter doesn't correspond to a named parameter from the
super constructor, then change it to be a normal parameter:
```dart
class A {
A({int? x});
}
class B extends A {
B({int? y});
}
```
SUPER_FORMAL_PARAMETER_WITHOUT_ASSOCIATED_POSITIONAL:
problemMessage: No associated positional super constructor parameter.
correctionMessage: Try using a normal parameter, or adding more positional parameters to the super constructor.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when there's a positional super
parameter in a constructor and the implicitly or explicitly invoked super
constructor doesn't have a positional parameter at the corresponding
index.
Positional super parameters are associated with positional parameters in
the super constructor by their index. That is, the first super parameter
is associated with the first positional parameter in the super
constructor, the second with the second, and so on.
#### Examples
The following code produces this diagnostic because the constructor in `B`
has a positional super parameter, but there's no positional parameter in
the super constructor in `A`:
```dart
class A {
A({int? x});
}
class B extends A {
B(super.[!x!]);
}
```
The following code produces this diagnostic because the constructor in `B`
has two positional super parameters, but there's only one positional
parameter in the super constructor in `A`, which means that there's no
corresponding parameter for `y`:
```dart
class A {
A(int x);
}
class B extends A {
B(super.x, super.[!y!]);
}
```
#### Common fixes
If the super constructor should have a positional parameter corresponding
to the super parameter, then update the super constructor appropriately:
```dart
class A {
A(int x, int y);
}
class B extends A {
B(super.x, super.y);
}
```
If the super constructor is correct, or can't be changed, then convert the
super parameter into a normal parameter:
```dart
class A {
A(int x);
}
class B extends A {
B(super.x, int y);
}
```
IMPLEMENTS_DEFERRED_CLASS:
sharedName: SUBTYPE_OF_DEFERRED_CLASS
problemMessage: "Classes and mixins can't implement deferred classes."
correctionMessage: Try specifying a different interface, removing the class from the list, or changing the import to not be deferred.
hasPublishedDocs: true
comment: No parameters.
MIXIN_DEFERRED_CLASS:
sharedName: SUBTYPE_OF_DEFERRED_CLASS
problemMessage: "Classes can't mixin deferred classes."
correctionMessage: Try changing the import to not be deferred.
hasPublishedDocs: true
comment: No parameters.
EXTENDS_DEFERRED_CLASS:
sharedName: SUBTYPE_OF_DEFERRED_CLASS
problemMessage: "Classes can't extend deferred classes."
correctionMessage: Try specifying a different superclass, or removing the extends clause.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a type (class or mixin) is a
subtype of a class from a library being imported using a deferred import.
The supertypes of a type must be compiled at the same time as the type, and
classes from deferred libraries aren't compiled until the library is
loaded.
For more information, check out
[Lazily loading a library](https://dart.dev/language/libraries#lazily-loading-a-library).
#### Example
Given a file `a.dart` that defines the class `A`:
```dart
%uri="lib/a.dart"
class A {}
```
The following code produces this diagnostic because the superclass of `B`
is declared in a deferred library:
```dart
import 'a.dart' deferred as a;
class B extends [!a.A!] {}
```
#### Common fixes
If you need to create a subtype of a type from the deferred library, then
remove the `deferred` keyword:
```dart
import 'a.dart' as a;
class B extends a.A {}
```
EXTENDS_DISALLOWED_CLASS:
sharedName: SUBTYPE_OF_DISALLOWED_TYPE
problemMessage: "Classes can't extend '{0}'."
correctionMessage: Try specifying a different superclass, or removing the extends clause.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the disallowed type
documentation: |-
#### Description
The analyzer produces this diagnostic when one of the restricted classes is
used in either an `extends`, `implements`, `with`, or `on` clause. The
classes `bool`, `double`, `FutureOr`, `int`, `Null`, `num`, and `String`
are all restricted in this way, to allow for more efficient
implementations.
#### Examples
The following code produces this diagnostic because `String` is used in an
`extends` clause:
```dart
class A extends [!String!] {}
```
The following code produces this diagnostic because `String` is used in an
`implements` clause:
```dart
class B implements [!String!] {}
```
The following code produces this diagnostic because `String` is used in a
`with` clause:
```dart
class C with [!String!] {}
```
The following code produces this diagnostic because `String` is used in an
`on` clause:
```dart
mixin M on [!String!] {}
```
#### Common fixes
If a different type should be specified, then replace the type:
```dart
class A extends Object {}
```
If there isn't a different type that would be appropriate, then remove the
type, and possibly the whole clause:
```dart
class B {}
```
MIXIN_OF_DISALLOWED_CLASS:
sharedName: SUBTYPE_OF_DISALLOWED_TYPE
problemMessage: "Classes can't mixin '{0}'."
correctionMessage: Try specifying a different class or mixin, or remove the class or mixin from the list.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the disallowed type
MIXIN_SUPER_CLASS_CONSTRAINT_DISALLOWED_CLASS:
sharedName: SUBTYPE_OF_DISALLOWED_TYPE
problemMessage: "'{0}' can't be used as a superclass constraint."
correctionMessage: "Try specifying a different super-class constraint, or remove the 'on' clause."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the disallowed type
IMPLEMENTS_DISALLOWED_CLASS:
sharedName: SUBTYPE_OF_DISALLOWED_TYPE
problemMessage: "Classes and mixins can't implement '{0}'."
correctionMessage: Try specifying a different interface, or remove the class from the list.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the disallowed type
EXTENDS_TYPE_ALIAS_EXPANDS_TO_TYPE_PARAMETER:
sharedName: SUPERTYPE_EXPANDS_TO_TYPE_PARAMETER
problemMessage: "A type alias that expands to a type parameter can't be used as a superclass."
correctionMessage: Try specifying a different superclass, or removing the extends clause.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a type alias that expands to a
type parameter is used in an `extends`, `implements`, `with`, or `on`
clause.
#### Example
The following code produces this diagnostic because the type alias `T`,
which expands to the type parameter `S`, is used in the `extends` clause of
the class `C`:
```dart
typedef T<S> = S;
class C extends [!T!]<Object> {}
```
#### Common fixes
Use the value of the type argument directly:
```dart
typedef T<S> = S;
class C extends Object {}
```
MIXIN_ON_TYPE_ALIAS_EXPANDS_TO_TYPE_PARAMETER:
sharedName: SUPERTYPE_EXPANDS_TO_TYPE_PARAMETER
problemMessage: "A type alias that expands to a type parameter can't be used as a superclass constraint."
hasPublishedDocs: true
comment: No parameters.
MIXIN_OF_TYPE_ALIAS_EXPANDS_TO_TYPE_PARAMETER:
sharedName: SUPERTYPE_EXPANDS_TO_TYPE_PARAMETER
problemMessage: "A type alias that expands to a type parameter can't be mixed in."
hasPublishedDocs: true
comment: No parameters.
IMPLEMENTS_TYPE_ALIAS_EXPANDS_TO_TYPE_PARAMETER:
sharedName: SUPERTYPE_EXPANDS_TO_TYPE_PARAMETER
problemMessage: "A type alias that expands to a type parameter can't be implemented."
correctionMessage: Try specifying a class or mixin, or removing the list.
hasPublishedDocs: true
comment: No parameters.
SUPER_INITIALIZER_IN_OBJECT:
problemMessage: "The class 'Object' can't invoke a constructor from a superclass."
comment: |-
7.6.1 Generative Constructors: Let <i>k</i> be a generative constructor. It
is a compile-time error if a generative constructor of class Object
includes a superinitializer.
SUPER_INVOCATION_NOT_LAST:
previousName: INVALID_SUPER_INVOCATION
problemMessage: "The superconstructor call must be last in an initializer list: '{0}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the superinitializer
documentation: |-
#### Description
The analyzer produces this diagnostic when the initializer list of a
constructor contains an invocation of a constructor in the superclass, but
the invocation isn't the last item in the initializer list.
#### Example
The following code produces this diagnostic because the invocation of the
superclass' constructor isn't the last item in the initializer list:
```dart
class A {
A(int x);
}
class B extends A {
B(int x) : [!super!](x), assert(x >= 0);
}
```
#### Common fixes
Move the invocation of the superclass' constructor to the end of the
initializer list:
```dart
class A {
A(int x);
}
class B extends A {
B(int x) : assert(x >= 0), super(x);
}
```
SUPER_IN_ENUM_CONSTRUCTOR:
problemMessage: The enum constructor can't have a 'super' initializer.
correctionMessage: Try removing the 'super' invocation.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the initializer list in a
constructor in an enum contains an invocation of a super constructor.
#### Example
The following code produces this diagnostic because the constructor in
the enum `E` has a super constructor invocation in the initializer list:
```dart
enum E {
e;
const E() : [!super!]();
}
```
#### Common fixes
Remove the super constructor invocation:
```dart
enum E {
e;
const E();
}
```
SUPER_IN_EXTENSION:
problemMessage: "The 'super' keyword can't be used in an extension because an extension doesn't have a superclass."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a member declared inside an
extension uses the `super` keyword . Extensions aren't classes and don't
have superclasses, so the `super` keyword serves no purpose.
#### Example
The following code produces this diagnostic because `super` can't be used
in an extension:
```dart
extension E on Object {
String get displayString => [!super!].toString();
}
```
#### Common fixes
Remove the `super` keyword :
```dart
extension E on Object {
String get displayString => toString();
}
```
SUPER_IN_INVALID_CONTEXT:
problemMessage: "Invalid context for 'super' invocation."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the keyword `super` is used
outside of an instance method.
#### Example
The following code produces this diagnostic because `super` is used in a
top-level function:
```dart
void f() {
[!super!].f();
}
```
#### Common fixes
Rewrite the code to not use `super`.
SUPER_IN_REDIRECTING_CONSTRUCTOR:
problemMessage: "The redirecting constructor can't have a 'super' initializer."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a constructor that redirects to
another constructor also attempts to invoke a constructor from the
superclass. The superclass constructor will be invoked when the constructor
that the redirecting constructor is redirected to is invoked.
#### Example
The following code produces this diagnostic because the constructor `C.a`
both redirects to `C.b` and invokes a constructor from the superclass:
```dart
class C {
C.a() : this.b(), [!super()!];
C.b();
}
```
#### Common fixes
Remove the invocation of the `super` constructor:
```dart
class C {
C.a() : this.b();
C.b();
}
```
SWITCH_CASE_COMPLETES_NORMALLY:
problemMessage: "The 'case' shouldn't complete normally."
correctionMessage: "Try adding 'break', 'return', or 'throw'."
comment: |-
No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when the statements following a
`case` label in a `switch` statement could fall through to the next `case`
or `default` label.
#### Example
The following code produces this diagnostic because the `case` label with
a value of zero (`0`) falls through to the `default` statements:
```dart
%language=2.18
void f(int a) {
switch (a) {
[!case!] 0:
print(0);
default:
return;
}
}
```
#### Common fixes
Change the flow of control so that the `case` won't fall through. There
are several ways that this can be done, including adding one of the
following at the end of the current list of statements:
- a `return` statement,
- a `throw` expression,
- a `break` statement,
- a `continue`, or
- an invocation of a function or method whose return type is `Never`.
SWITCH_EXPRESSION_NOT_ASSIGNABLE:
problemMessage: "Type '{0}' of the switch expression isn't assignable to the type '{1}' of case expressions."
hasPublishedDocs: true
comment: |-
Parameters:
0: the static type of the switch expression
1: the static type of the case expressions
documentation: |-
#### Description
The analyzer produces this diagnostic when the type of the expression in a
`switch` statement isn't assignable to the type of the expressions in the
`case` clauses.
#### Example
The following code produces this diagnostic because the type of `s`
(`String`) isn't assignable to the type of `0` (`int`):
```dart
%language=2.9
void f(String s) {
switch ([!s!]) {
case 0:
break;
}
}
```
#### Common fixes
If the type of the `case` expressions is correct, then change the
expression in the `switch` statement to have the correct type:
```dart
%language=2.9
void f(String s) {
switch (int.parse(s)) {
case 0:
break;
}
}
```
If the type of the `switch` expression is correct, then change the `case`
expressions to have the correct type:
```dart
%language=2.9
void f(String s) {
switch (s) {
case '0':
break;
}
}
```
TEAROFF_OF_GENERATIVE_CONSTRUCTOR_OF_ABSTRACT_CLASS:
problemMessage: "A generative constructor of an abstract class can't be torn off."
correctionMessage: Try tearing off a constructor of a concrete class, or a non-generative constructor.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a generative constructor from an
abstract class is being torn off. This isn't allowed because it isn't valid
to create an instance of an abstract class, which means that there isn't
any valid use for the torn off constructor.
#### Example
The following code produces this diagnostic because the constructor `C.new`
is being torn off and the class `C` is an abstract class:
```dart
abstract class C {
C();
}
void f() {
[!C.new!];
}
```
#### Common fixes
Tear off the constructor of a concrete class.
THROW_OF_INVALID_TYPE:
problemMessage: "The type '{0}' of the thrown expression must be assignable to 'Object'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the type that can't be thrown
documentation: |-
#### Description
The analyzer produces this diagnostic when the type of the expression in a
throw expression isn't assignable to `Object`. It isn't valid to throw
`null`, so it isn't valid to use an expression that might evaluate to
`null`.
#### Example
The following code produces this diagnostic because `s` might be `null`:
```dart
void f(String? s) {
throw [!s!];
}
```
#### Common fixes
Add an explicit null-check to the expression:
```dart
void f(String? s) {
throw s!;
}
```
TOP_LEVEL_CYCLE:
problemMessage: "The type of '{0}' can't be inferred because it depends on itself through the cycle: {1}."
correctionMessage: Try adding an explicit type to one or more of the variables in the cycle in order to break the cycle.
hasPublishedDocs: true
comment: |-
Parameters:
0: the element whose type could not be inferred.
1: The [TopLevelInferenceError]'s arguments that led to the cycle.
documentation: |-
#### Description
The analyzer produces this diagnostic when a top-level variable has no type
annotation and the variable's initializer refers to the variable, either
directly or indirectly.
#### Example
The following code produces this diagnostic because the variables `x` and
`y` are defined in terms of each other, and neither has an explicit type,
so the type of the other can't be inferred:
```dart
var x = y;
var y = [!x!];
```
#### Common fixes
If the two variables don't need to refer to each other, then break the
cycle:
```dart
var x = 0;
var y = x;
```
If the two variables need to refer to each other, then give at least one of
them an explicit type:
```dart
int x = y;
var y = x;
```
Note, however, that while this code doesn't produce any diagnostics, it
will produce a stack overflow at runtime unless at least one of the
variables is assigned a value that doesn't depend on the other variables
before any of the variables in the cycle are referenced.
TYPE_ALIAS_CANNOT_REFERENCE_ITSELF:
problemMessage: "Typedefs can't reference themselves directly or recursively via another typedef."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a typedef refers to itself,
either directly or indirectly.
#### Example
The following code produces this diagnostic because `F` depends on itself
indirectly through `G`:
```dart
typedef [!F!] = void Function(G);
typedef G = void Function(F);
```
#### Common fixes
Change one or more of the typedefs in the cycle so that none of them refer
to themselves:
```dart
typedef F = void Function(G);
typedef G = void Function(int);
```
TYPE_ANNOTATION_DEFERRED_CLASS:
problemMessage: "The deferred type '{0}' can't be used in a declaration, cast, or type test."
correctionMessage: Try using a different type, or changing the import to not be deferred.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the type that is deferred and being used in a type
annotation
documentation: |-
#### Description
The analyzer produces this diagnostic when the type annotation is in a
variable declaration, or the type used in a cast (`as`) or type test (`is`)
is a type declared in a library that is imported using a deferred import.
These types are required to be available at compile time, but aren't.
For more information, check out
[Lazily loading a library](https://dart.dev/language/libraries#lazily-loading-a-library).
#### Example
The following code produces this diagnostic because the type of the
parameter `f` is imported from a deferred library:
```dart
import 'dart:io' deferred as io;
void f([!io.File!] f) {}
```
#### Common fixes
If you need to reference the imported type, then remove the `deferred`
keyword:
```dart
import 'dart:io' as io;
void f(io.File f) {}
```
If the import is required to be deferred and there's another type that is
appropriate, then use that type in place of the type from the deferred
library.
TYPE_ARGUMENT_NOT_MATCHING_BOUNDS:
problemMessage: "'{0}' doesn't conform to the bound '{2}' of the type parameter '{1}'."
correctionMessage: "Try using a type that is or is a subclass of '{2}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the type used in the instance creation that should be
limited by the bound as specified in the class declaration
1: the name of the type parameter
2: the substituted bound of the type parameter
documentation: |-
#### Description
The analyzer produces this diagnostic when a type argument isn't the same
as or a subclass of the bounds of the corresponding type parameter.
#### Example
The following code produces this diagnostic because `String` isn't a
subclass of `num`:
```dart
class A<E extends num> {}
var a = A<[!String!]>();
```
#### Common fixes
Change the type argument to be a subclass of the bounds:
```dart
class A<E extends num> {}
var a = A<int>();
```
TYPE_PARAMETER_REFERENCED_BY_STATIC:
problemMessage: "Static members can't reference type parameters of the class."
correctionMessage: Try removing the reference to the type parameter, or making the member an instance member.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a static member references a
type parameter that is declared for the class. Type parameters only have
meaning for instances of the class.
#### Example
The following code produces this diagnostic because the static method
`hasType` has a reference to the type parameter `T`:
```dart
class C<T> {
static bool hasType(Object o) => o is [!T!];
}
```
#### Common fixes
If the member can be an instance member, then remove the keyword `static`:
```dart
class C<T> {
bool hasType(Object o) => o is T;
}
```
If the member must be a static member, then make the member be generic:
```dart
class C<T> {
static bool hasType<S>(Object o) => o is S;
}
```
Note, however, that there isn't a relationship between `T` and `S`, so this
second option changes the semantics from what was likely to be intended.
TYPE_PARAMETER_SUPERTYPE_OF_ITS_BOUND:
problemMessage: "'{0}' can't be a supertype of its upper bound."
correctionMessage: "Try using a type that is the same as or a subclass of '{1}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the type parameter
1: the name of the bounding type
See [CompileTimeErrorCode.TYPE_ARGUMENT_NOT_MATCHING_BOUNDS].
documentation: |-
#### Description
The analyzer produces this diagnostic when the bound of a type parameter
(the type following the `extends` keyword) is either directly or indirectly
the type parameter itself. Stating that the type parameter must be the same
as itself or a subtype of itself or a subtype of itself isn't helpful
because it will always be the same as itself.
#### Examples
The following code produces this diagnostic because the bound of `T` is
`T`:
```dart
class C<[!T!] extends T> {}
```
The following code produces this diagnostic because the bound of `T1` is
`T2`, and the bound of `T2` is `T1`, effectively making the bound of `T1`
be `T1`:
```dart
class C<[!T1!] extends T2, T2 extends T1> {}
```
#### Common fixes
If the type parameter needs to be a subclass of some type, then replace the
bound with the required type:
```dart
class C<T extends num> {}
```
If the type parameter can be any type, then remove the `extends` clause:
```dart
class C<T> {}
```
TYPE_TEST_WITH_NON_TYPE:
problemMessage: "The name '{0}' isn't a type and can't be used in an 'is' expression."
correctionMessage: Try correcting the name to match an existing type.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the type
documentation: |-
#### Description
The analyzer produces this diagnostic when the right-hand side of an `is`
or `is!` test isn't a type.
#### Example
The following code produces this diagnostic because the right-hand side is
a parameter, not a type:
```dart
typedef B = int Function(int);
void f(Object a, B b) {
if (a is [!b!]) {
return;
}
}
```
#### Common fixes
If you intended to use a type test, then replace the right-hand side with a
type:
```dart
typedef B = int Function(int);
void f(Object a, B b) {
if (a is B) {
return;
}
}
```
If you intended to use a different kind of test, then change the test:
```dart
typedef B = int Function(int);
void f(Object a, B b) {
if (a == b) {
return;
}
}
```
TYPE_TEST_WITH_UNDEFINED_NAME:
problemMessage: "The name '{0}' isn't defined, so it can't be used in an 'is' expression."
correctionMessage: "Try changing the name to the name of an existing type, or creating a type with the name '{0}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the type
documentation: |-
#### Description
The analyzer produces this diagnostic when the name following the `is` in a
type test expression isn't defined.
#### Example
The following code produces this diagnostic because the name `Srting` isn't
defined:
```dart
void f(Object o) {
if (o is [!Srting!]) {
// ...
}
}
```
#### Common fixes
Replace the name with the name of a type:
```dart
void f(Object o) {
if (o is String) {
// ...
}
}
```
UNCHECKED_USE_OF_NULLABLE_VALUE_IN_SPREAD:
sharedName: UNCHECKED_USE_OF_NULLABLE_VALUE
problemMessage: "A nullable expression can't be used in a spread."
correctionMessage: "Try checking that the value isn't 'null' before using it in a spread, or use a null-aware spread."
hasPublishedDocs: true
UNCHECKED_INVOCATION_OF_NULLABLE_VALUE:
sharedName: UNCHECKED_USE_OF_NULLABLE_VALUE
problemMessage: "The function can't be unconditionally invoked because it can be 'null'."
correctionMessage: "Try adding a null check ('!')."
hasPublishedDocs: true
UNCHECKED_METHOD_INVOCATION_OF_NULLABLE_VALUE:
sharedName: UNCHECKED_USE_OF_NULLABLE_VALUE
problemMessage: "The method '{0}' can't be unconditionally invoked because the receiver can be 'null'."
correctionMessage: "Try making the call conditional (using '?.') or adding a null check to the target ('!')."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the method
UNCHECKED_OPERATOR_INVOCATION_OF_NULLABLE_VALUE:
sharedName: UNCHECKED_USE_OF_NULLABLE_VALUE
problemMessage: "The operator '{0}' can't be unconditionally invoked because the receiver can be 'null'."
correctionMessage: "Try adding a null check to the target ('!')."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the operator
UNCHECKED_USE_OF_NULLABLE_VALUE_IN_YIELD_EACH:
sharedName: UNCHECKED_USE_OF_NULLABLE_VALUE
problemMessage: "A nullable expression can't be used in a yield-each statement."
correctionMessage: "Try checking that the value isn't 'null' before using it in a yield-each statement."
hasPublishedDocs: true
UNCHECKED_USE_OF_NULLABLE_VALUE_AS_CONDITION:
sharedName: UNCHECKED_USE_OF_NULLABLE_VALUE
problemMessage: "A nullable expression can't be used as a condition."
correctionMessage: "Try checking that the value isn't 'null' before using it as a condition."
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when an expression whose type is
[potentially non-nullable][] is dereferenced without first verifying that
the value isn't `null`.
#### Example
The following code produces this diagnostic because `s` can be `null` at
the point where it's referenced:
```dart
void f(String? s) {
if (s.[!length!] > 3) {
// ...
}
}
```
#### Common fixes
If the value really can be `null`, then add a test to ensure that members
are only accessed when the value isn't `null`:
```dart
void f(String? s) {
if (s != null && s.length > 3) {
// ...
}
}
```
If the expression is a variable and the value should never be `null`, then
change the type of the variable to be non-nullable:
```dart
void f(String s) {
if (s.length > 3) {
// ...
}
}
```
If you believe that the value of the expression should never be `null`, but
you can't change the type of the variable, and you're willing to risk
having an exception thrown at runtime if you're wrong, then you can assert
that the value isn't null:
```dart
void f(String? s) {
if (s!.length > 3) {
// ...
}
}
```
UNCHECKED_USE_OF_NULLABLE_VALUE_AS_ITERATOR:
sharedName: UNCHECKED_USE_OF_NULLABLE_VALUE
problemMessage: "A nullable expression can't be used as an iterator in a for-in loop."
correctionMessage: "Try checking that the value isn't 'null' before using it as an iterator."
hasPublishedDocs: true
UNCHECKED_PROPERTY_ACCESS_OF_NULLABLE_VALUE:
sharedName: UNCHECKED_USE_OF_NULLABLE_VALUE
problemMessage: "The property '{0}' can't be unconditionally accessed because the receiver can be 'null'."
correctionMessage: "Try making the access conditional (using '?.') or adding a null check to the target ('!')."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the property
UNDEFINED_ANNOTATION:
problemMessage: "Undefined name '{0}' used as an annotation."
correctionMessage: Try defining the name or importing it from another library.
isUnresolvedIdentifier: true
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the annotation
documentation: |-
#### Description
The analyzer produces this diagnostic when a name that isn't defined is
used as an annotation.
#### Example
The following code produces this diagnostic because the name `undefined`
isn't defined:
```dart
[!@undefined!]
void f() {}
```
#### Common fixes
If the name is correct, but it isn't declared yet, then declare the name as
a constant value:
```dart
const undefined = 'undefined';
@undefined
void f() {}
```
If the name is wrong, replace the name with the name of a valid constant:
```dart
@deprecated
void f() {}
```
Otherwise, remove the annotation.
UNDEFINED_CLASS:
problemMessage: "Undefined class '{0}'."
correctionMessage: "Try changing the name to the name of an existing class, or creating a class with the name '{0}'."
isUnresolvedIdentifier: true
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the undefined class
documentation: |-
#### Description
The analyzer produces this diagnostic when it encounters an identifier that
appears to be the name of a class but either isn't defined or isn't visible
in the scope in which it's being referenced.
#### Example
The following code produces this diagnostic because `Piont` isn't defined:
```dart
class Point {}
void f([!Piont!] p) {}
```
#### Common fixes
If the identifier isn't defined, then either define it or replace it with
the name of a class that is defined. The example above can be corrected by
fixing the spelling of the class:
```dart
class Point {}
void f(Point p) {}
```
If the class is defined but isn't visible, then you probably need to add an
import.
UNDEFINED_CLASS_BOOLEAN:
sharedName: UNDEFINED_CLASS
problemMessage: "Undefined class '{0}'."
correctionMessage: "Try using the type 'bool'."
isUnresolvedIdentifier: true
hasPublishedDocs: true
comment: |-
Same as [CompileTimeErrorCode.UNDEFINED_CLASS], but to catch using
"boolean" instead of "bool" in order to improve the correction message.
Parameters:
0: the name of the undefined class
UNDEFINED_CONSTRUCTOR_IN_INITIALIZER:
problemMessage: "The class '{0}' doesn't have a constructor named '{1}'."
correctionMessage: "Try defining a constructor named '{1}' in '{0}', or invoking a different constructor."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the superclass that does not define the invoked constructor
1: the name of the constructor being invoked
documentation: |-
#### Description
The analyzer produces this diagnostic when a superclass constructor is
invoked in the initializer list of a constructor, but the superclass
doesn't define the constructor being invoked.
#### Examples
The following code produces this diagnostic because `A` doesn't have an
unnamed constructor:
```dart
class A {
A.n();
}
class B extends A {
B() : [!super()!];
}
```
The following code produces this diagnostic because `A` doesn't have a
constructor named `m`:
```dart
class A {
A.n();
}
class B extends A {
B() : [!super.m()!];
}
```
#### Common fixes
If the superclass defines a constructor that should be invoked, then change
the constructor being invoked:
```dart
class A {
A.n();
}
class B extends A {
B() : super.n();
}
```
If the superclass doesn't define an appropriate constructor, then define
the constructor being invoked:
```dart
class A {
A.m();
A.n();
}
class B extends A {
B() : super.m();
}
```
UNDEFINED_CONSTRUCTOR_IN_INITIALIZER_DEFAULT:
sharedName: UNDEFINED_CONSTRUCTOR_IN_INITIALIZER
problemMessage: "The class '{0}' doesn't have an unnamed constructor."
correctionMessage: "Try defining an unnamed constructor in '{0}', or invoking a different constructor."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the superclass that does not define the invoked constructor
UNDEFINED_ENUM_CONSTANT:
problemMessage: "There's no constant named '{0}' in '{1}'."
correctionMessage: "Try correcting the name to the name of an existing constant, or defining a constant named '{0}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the enum constant that is not defined
1: the name of the enum used to access the constant
documentation: |-
#### Description
The analyzer produces this diagnostic when it encounters an identifier that
appears to be the name of an enum constant, and the name either isn't
defined or isn't visible in the scope in which it's being referenced.
#### Example
The following code produces this diagnostic because `E` doesn't define a
constant named `c`:
```dart
enum E {a, b}
var e = E.[!c!];
```
#### Common fixes
If the constant should be defined, then add it to the declaration of the
enum:
```dart
enum E {a, b, c}
var e = E.c;
```
If the constant shouldn't be defined, then change the name to the name of
an existing constant:
```dart
enum E {a, b}
var e = E.b;
```
UNDEFINED_ENUM_CONSTRUCTOR_NAMED:
sharedName: UNDEFINED_ENUM_CONSTRUCTOR
problemMessage: The enum doesn't have a constructor named '{0}'.
correctionMessage: Try correcting the name to the name of an existing constructor, or defining constructor with the name '{0}'.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the constructor that is undefined
documentation: |-
#### Description
The analyzer produces this diagnostic when the constructor invoked to
initialize an enum constant doesn't exist.
#### Examples
The following code produces this diagnostic because the enum constant `c`
is being initialized by the unnamed constructor, but there's no unnamed
constructor defined in `E`:
```dart
enum E {
[!c!]();
const E.x();
}
```
The following code produces this diagnostic because the enum constant `c`
is being initialized by the constructor named `x`, but there's no
constructor named `x` defined in `E`:
```dart
enum E {
c.[!x!]();
const E.y();
}
```
#### Common fixes
If the enum constant is being initialized by the unnamed constructor and
one of the named constructors should have been used, then add the name of
the constructor:
```dart
enum E {
c.x();
const E.x();
}
```
If the enum constant is being initialized by the unnamed constructor and
none of the named constructors are appropriate, then define the unnamed
constructor:
```dart
enum E {
c();
const E();
}
```
If the enum constant is being initialized by a named constructor and one
of the existing constructors should have been used, then change the name
of the constructor being invoked (or remove it if the unnamed constructor
should be used):
```dart
enum E {
c.y();
const E();
const E.y();
}
```
If the enum constant is being initialized by a named constructor and none
of the existing constructors should have been used, then define a
constructor with the name that was used:
```dart
enum E {
c.x();
const E.x();
}
```
UNDEFINED_ENUM_CONSTRUCTOR_UNNAMED:
sharedName: UNDEFINED_ENUM_CONSTRUCTOR
problemMessage: The enum doesn't have an unnamed constructor.
correctionMessage: Try adding the name of an existing constructor, or defining an unnamed constructor.
hasPublishedDocs: true
UNDEFINED_EXTENSION_GETTER:
problemMessage: "The getter '{0}' isn't defined for the extension '{1}'."
correctionMessage: "Try correcting the name to the name of an existing getter, or defining a getter named '{0}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the getter that is undefined
1: the name of the extension that was explicitly specified
documentation: |-
#### Description
The analyzer produces this diagnostic when an extension override is used to
invoke a getter, but the getter isn't defined by the specified extension.
The analyzer also produces this diagnostic when a static getter is
referenced but isn't defined by the specified extension.
#### Examples
The following code produces this diagnostic because the extension `E`
doesn't declare an instance getter named `b`:
```dart
extension E on String {
String get a => 'a';
}
extension F on String {
String get b => 'b';
}
void f() {
E('c').[!b!];
}
```
The following code produces this diagnostic because the extension `E`
doesn't declare a static getter named `a`:
```dart
extension E on String {}
var x = E.[!a!];
```
#### Common fixes
If the name of the getter is incorrect, then change it to the name of an
existing getter:
```dart
extension E on String {
String get a => 'a';
}
extension F on String {
String get b => 'b';
}
void f() {
E('c').a;
}
```
If the name of the getter is correct but the name of the extension is
wrong, then change the name of the extension to the correct name:
```dart
extension E on String {
String get a => 'a';
}
extension F on String {
String get b => 'b';
}
void f() {
F('c').b;
}
```
If the name of the getter and extension are both correct, but the getter
isn't defined, then define the getter:
```dart
extension E on String {
String get a => 'a';
String get b => 'z';
}
extension F on String {
String get b => 'b';
}
void f() {
E('c').b;
}
```
UNDEFINED_EXTENSION_METHOD:
problemMessage: "The method '{0}' isn't defined for the extension '{1}'."
correctionMessage: "Try correcting the name to the name of an existing method, or defining a method named '{0}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the method that is undefined
1: the name of the extension that was explicitly specified
documentation: |-
#### Description
The analyzer produces this diagnostic when an extension override is used to
invoke a method, but the method isn't defined by the specified extension.
The analyzer also produces this diagnostic when a static method is
referenced but isn't defined by the specified extension.
#### Examples
The following code produces this diagnostic because the extension `E`
doesn't declare an instance method named `b`:
```dart
extension E on String {
String a() => 'a';
}
extension F on String {
String b() => 'b';
}
void f() {
E('c').[!b!]();
}
```
The following code produces this diagnostic because the extension `E`
doesn't declare a static method named `a`:
```dart
extension E on String {}
var x = E.[!a!]();
```
#### Common fixes
If the name of the method is incorrect, then change it to the name of an
existing method:
```dart
extension E on String {
String a() => 'a';
}
extension F on String {
String b() => 'b';
}
void f() {
E('c').a();
}
```
If the name of the method is correct, but the name of the extension is
wrong, then change the name of the extension to the correct name:
```dart
extension E on String {
String a() => 'a';
}
extension F on String {
String b() => 'b';
}
void f() {
F('c').b();
}
```
If the name of the method and extension are both correct, but the method
isn't defined, then define the method:
```dart
extension E on String {
String a() => 'a';
String b() => 'z';
}
extension F on String {
String b() => 'b';
}
void f() {
E('c').b();
}
```
UNDEFINED_EXTENSION_OPERATOR:
problemMessage: "The operator '{0}' isn't defined for the extension '{1}'."
correctionMessage: "Try defining the operator '{0}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the operator that is undefined
1: the name of the extension that was explicitly specified
documentation: |-
#### Description
The analyzer produces this diagnostic when an operator is invoked on a
specific extension when that extension doesn't implement the operator.
#### Example
The following code produces this diagnostic because the extension `E`
doesn't define the operator `*`:
```dart
var x = E('') [!*!] 4;
extension E on String {}
```
#### Common fixes
If the extension is expected to implement the operator, then add an
implementation of the operator to the extension:
```dart
var x = E('') * 4;
extension E on String {
int operator *(int multiplier) => length * multiplier;
}
```
If the operator is defined by a different extension, then change the name
of the extension to the name of the one that defines the operator.
If the operator is defined on the argument of the extension override, then
remove the extension override:
```dart
var x = '' * 4;
extension E on String {}
```
UNDEFINED_EXTENSION_SETTER:
problemMessage: "The setter '{0}' isn't defined for the extension '{1}'."
correctionMessage: "Try correcting the name to the name of an existing setter, or defining a setter named '{0}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the setter that is undefined
1: the name of the extension that was explicitly specified
documentation: |-
#### Description
The analyzer produces this diagnostic when an extension override is used to
invoke a setter, but the setter isn't defined by the specified extension.
The analyzer also produces this diagnostic when a static setter is
referenced but isn't defined by the specified extension.
#### Examples
The following code produces this diagnostic because the extension `E`
doesn't declare an instance setter named `b`:
```dart
extension E on String {
set a(String v) {}
}
extension F on String {
set b(String v) {}
}
void f() {
E('c').[!b!] = 'd';
}
```
The following code produces this diagnostic because the extension `E`
doesn't declare a static setter named `a`:
```dart
extension E on String {}
void f() {
E.[!a!] = 3;
}
```
#### Common fixes
If the name of the setter is incorrect, then change it to the name of an
existing setter:
```dart
extension E on String {
set a(String v) {}
}
extension F on String {
set b(String v) {}
}
void f() {
E('c').a = 'd';
}
```
If the name of the setter is correct, but the name of the extension is
wrong, then change the name of the extension to the correct name:
```dart
extension E on String {
set a(String v) {}
}
extension F on String {
set b(String v) {}
}
void f() {
F('c').b = 'd';
}
```
If the name of the setter and extension are both correct, but the setter
isn't defined, then define the setter:
```dart
extension E on String {
set a(String v) {}
set b(String v) {}
}
extension F on String {
set b(String v) {}
}
void f() {
E('c').b = 'd';
}
```
UNDEFINED_FUNCTION:
problemMessage: "The function '{0}' isn't defined."
correctionMessage: "Try importing the library that defines '{0}', correcting the name to the name of an existing function, or defining a function named '{0}'."
isUnresolvedIdentifier: true
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the method that is undefined
documentation: |-
#### Description
The analyzer produces this diagnostic when it encounters an identifier that
appears to be the name of a function but either isn't defined or isn't
visible in the scope in which it's being referenced.
#### Example
The following code produces this diagnostic because the name `emty` isn't
defined:
```dart
List<int> empty() => [];
void main() {
print([!emty!]());
}
```
#### Common fixes
If the identifier isn't defined, then either define it or replace it with
the name of a function that is defined. The example above can be corrected
by fixing the spelling of the function:
```dart
List<int> empty() => [];
void main() {
print(empty());
}
```
If the function is defined but isn't visible, then you probably need to add
an import or re-arrange your code to make the function visible.
UNDEFINED_GETTER:
problemMessage: "The getter '{0}' isn't defined for the type '{1}'."
correctionMessage: "Try importing the library that defines '{0}', correcting the name to the name of an existing getter, or defining a getter or field named '{0}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the getter
1: the name of the enclosing type where the getter is being looked for
documentation: |-
#### Description
The analyzer produces this diagnostic when it encounters an identifier that
appears to be the name of a getter but either isn't defined or isn't
visible in the scope in which it's being referenced.
#### Example
The following code produces this diagnostic because `String` has no member
named `len`:
```dart
int f(String s) => s.[!len!];
```
#### Common fixes
If the identifier isn't defined, then either define it or replace it with
the name of a getter that is defined. The example above can be corrected by
fixing the spelling of the getter:
```dart
int f(String s) => s.length;
```
UNDEFINED_GETTER_ON_FUNCTION_TYPE:
sharedName: UNDEFINED_GETTER
problemMessage: "The getter '{0}' isn't defined for the '{1}' function type."
correctionMessage: "Try wrapping the function type alias in parentheses in order to access '{0}' as an extension getter on 'Type'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the getter
1: the name of the function type alias
UNDEFINED_IDENTIFIER:
problemMessage: "Undefined name '{0}'."
correctionMessage: Try correcting the name to one that is defined, or defining the name.
isUnresolvedIdentifier: true
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the identifier
documentation: |-
#### Description
The analyzer produces this diagnostic when it encounters an identifier that
either isn't defined or isn't visible in the scope in which it's being
referenced.
#### Example
The following code produces this diagnostic because the name `rihgt` isn't
defined:
```dart
int min(int left, int right) => left <= [!rihgt!] ? left : right;
```
#### Common fixes
If the identifier isn't defined, then either define it or replace it with
an identifier that is defined. The example above can be corrected by
fixing the spelling of the variable:
```dart
int min(int left, int right) => left <= right ? left : right;
```
If the identifier is defined but isn't visible, then you probably need to
add an import or re-arrange your code to make the identifier visible.
UNDEFINED_IDENTIFIER_AWAIT:
problemMessage: "Undefined name 'await' in function body not marked with 'async'."
correctionMessage: "Try correcting the name to one that is defined, defining the name, or adding 'async' to the enclosing function body."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the name `await` is used in a
method or function body without being declared, and the body isn't marked
with the `async` keyword. The name `await` only introduces an await
expression in an asynchronous function.
#### Example
The following code produces this diagnostic because the name `await` is
used in the body of `f` even though the body of `f` isn't marked with the
`async` keyword:
```dart
void f(p) { [!await!] p; }
```
#### Common fixes
Add the keyword `async` to the function body:
```dart
void f(p) async { await p; }
```
UNDEFINED_METHOD:
problemMessage: "The method '{0}' isn't defined for the type '{1}'."
correctionMessage: "Try correcting the name to the name of an existing method, or defining a method named '{0}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the method that is undefined
1: the resolved type name that the method lookup is happening on
documentation: |-
#### Description
The analyzer produces this diagnostic when it encounters an identifier that
appears to be the name of a method but either isn't defined or isn't
visible in the scope in which it's being referenced.
#### Example
The following code produces this diagnostic because the identifier
`removeMiddle` isn't defined:
```dart
int f(List<int> l) => l.[!removeMiddle!]();
```
#### Common fixes
If the identifier isn't defined, then either define it or replace it with
the name of a method that is defined. The example above can be corrected by
fixing the spelling of the method:
```dart
int f(List<int> l) => l.removeLast();
```
UNDEFINED_METHOD_ON_FUNCTION_TYPE:
sharedName: UNDEFINED_METHOD
problemMessage: "The method '{0}' isn't defined for the '{1}' function type."
correctionMessage: "Try wrapping the function type alias in parentheses in order to access '{0}' as an extension method on 'Type'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the method
1: the name of the function type alias
UNDEFINED_NAMED_PARAMETER:
problemMessage: "The named parameter '{0}' isn't defined."
correctionMessage: "Try correcting the name to an existing named parameter's name, or defining a named parameter with the name '{0}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the requested named parameter
documentation: |-
#### Description
The analyzer produces this diagnostic when a method or function invocation
has a named argument, but the method or function being invoked doesn't
define a parameter with the same name.
#### Example
The following code produces this diagnostic because `m` doesn't declare a
named parameter named `a`:
```dart
%language=2.9
class C {
m({int b}) {}
}
void f(C c) {
c.m([!a!]: 1);
}
```
#### Common fixes
If the argument name is mistyped, then replace it with the correct name.
The example above can be fixed by changing `a` to `b`:
```dart
%language=2.9
class C {
m({int b}) {}
}
void f(C c) {
c.m(b: 1);
}
```
If a subclass adds a parameter with the name in question, then cast the
receiver to the subclass:
```dart
%language=2.9
class C {
m({int b}) {}
}
class D extends C {
m({int a, int b}) {}
}
void f(C c) {
(c as D).m(a: 1);
}
```
If the parameter should be added to the function, then add it:
```dart
%language=2.9
class C {
m({int a, int b}) {}
}
void f(C c) {
c.m(a: 1);
}
```
UNDEFINED_OPERATOR:
problemMessage: "The operator '{0}' isn't defined for the type '{1}'."
correctionMessage: "Try defining the operator '{0}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the operator
1: the name of the enclosing type where the operator is being looked for
documentation: |-
#### Description
The analyzer produces this diagnostic when a user-definable operator is
invoked on an object for which the operator isn't defined.
#### Example
The following code produces this diagnostic because the class `C` doesn't
define the operator `+`:
```dart
class C {}
C f(C c) => c [!+!] 2;
```
#### Common fixes
If the operator should be defined for the class, then define it:
```dart
class C {
C operator +(int i) => this;
}
C f(C c) => c + 2;
```
UNDEFINED_PREFIXED_NAME:
problemMessage: "The name '{0}' is being referenced through the prefix '{1}', but it isn't defined in any of the libraries imported using that prefix."
correctionMessage: "Try correcting the prefix or importing the library that defines '{0}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the reference
1: the name of the prefix
documentation: |-
#### Description
The analyzer produces this diagnostic when a prefixed identifier is found
where the prefix is valid, but the identifier isn't declared in any of the
libraries imported using that prefix.
#### Example
The following code produces this diagnostic because `dart:core` doesn't
define anything named `a`:
```dart
import 'dart:core' as p;
void f() {
p.[!a!];
}
```
#### Common fixes
If the library in which the name is declared isn't imported yet, add an
import for the library.
If the name is wrong, then change it to one of the names that's declared in
the imported libraries.
UNDEFINED_SETTER:
problemMessage: "The setter '{0}' isn't defined for the type '{1}'."
correctionMessage: "Try importing the library that defines '{0}', correcting the name to the name of an existing setter, or defining a setter or field named '{0}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the setter
1: the name of the enclosing type where the setter is being looked for
documentation: |-
#### Description
The analyzer produces this diagnostic when it encounters an identifier that
appears to be the name of a setter but either isn't defined or isn't
visible in the scope in which the identifier is being referenced.
#### Example
The following code produces this diagnostic because there isn't a setter
named `z`:
```dart
class C {
int x = 0;
void m(int y) {
this.[!z!] = y;
}
}
```
#### Common fixes
If the identifier isn't defined, then either define it or replace it with
the name of a setter that is defined. The example above can be corrected by
fixing the spelling of the setter:
```dart
class C {
int x = 0;
void m(int y) {
this.x = y;
}
}
```
UNDEFINED_SETTER_ON_FUNCTION_TYPE:
sharedName: UNDEFINED_SETTER
problemMessage: "The setter '{0}' isn't defined for the '{1}' function type."
correctionMessage: "Try wrapping the function type alias in parentheses in order to access '{0}' as an extension getter on 'Type'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the setter
1: the name of the function type alias
UNDEFINED_SUPER_GETTER:
sharedName: UNDEFINED_SUPER_MEMBER
problemMessage: "The getter '{0}' isn't defined in a superclass of '{1}'."
correctionMessage: "Try correcting the name to the name of an existing getter, or defining a getter or field named '{0}' in a superclass."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the getter
1: the name of the enclosing type where the getter is being looked for
UNDEFINED_SUPER_METHOD:
sharedName: UNDEFINED_SUPER_MEMBER
previousName: UNDEFINED_SUPER_METHOD
problemMessage: "The method '{0}' isn't defined in a superclass of '{1}'."
correctionMessage: "Try correcting the name to the name of an existing method, or defining a method named '{0}' in a superclass."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the method that is undefined
1: the resolved type name that the method lookup is happening on
documentation: |-
#### Description
The analyzer produces this diagnostic when an inherited member (method,
getter, setter, or operator) is referenced using `super`, but there's no
member with that name in the superclass chain.
#### Examples
The following code produces this diagnostic because `Object` doesn't define
a method named `n`:
```dart
class C {
void m() {
super.[!n!]();
}
}
```
The following code produces this diagnostic because `Object` doesn't define
a getter named `g`:
```dart
class C {
void m() {
super.[!g!];
}
}
```
#### Common fixes
If the inherited member you intend to invoke has a different name, then
make the name of the invoked member match the inherited member.
If the member you intend to invoke is defined in the same class, then
remove the `super.`.
If the member isn't defined, then either add the member to one of the
superclasses or remove the invocation.
UNDEFINED_SUPER_OPERATOR:
sharedName: UNDEFINED_SUPER_MEMBER
problemMessage: "The operator '{0}' isn't defined in a superclass of '{1}'."
correctionMessage: "Try defining the operator '{0}' in a superclass."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the operator
1: the name of the enclosing type where the operator is being looked for
UNDEFINED_SUPER_SETTER:
sharedName: UNDEFINED_SUPER_MEMBER
problemMessage: "The setter '{0}' isn't defined in a superclass of '{1}'."
correctionMessage: "Try correcting the name to the name of an existing setter, or defining a setter or field named '{0}' in a superclass."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the setter
1: the name of the enclosing type where the setter is being looked for
UNQUALIFIED_REFERENCE_TO_NON_LOCAL_STATIC_MEMBER:
problemMessage: Static members from supertypes must be qualified by the name of the defining type.
correctionMessage: "Try adding '{0}.' before the name."
hasPublishedDocs: true
comment: |-
This is a specialization of [INSTANCE_ACCESS_TO_STATIC_MEMBER] that is used
when we are able to find the name defined in a supertype. It exists to
provide a more informative error message.
Parameters:
0: the name of the defining type
documentation: |-
#### Description
The analyzer produces this diagnostic when code in one class references a
static member in a superclass without prefixing the member's name with the
name of the superclass. Static members can only be referenced without a
prefix in the class in which they're declared.
#### Example
The following code produces this diagnostic because the static field `x` is
referenced in the getter `g` without prefixing it with the name of the
defining class:
```dart
class A {
static int x = 3;
}
class B extends A {
int get g => [!x!];
}
```
#### Common fixes
Prefix the name of the static member with the name of the declaring class:
```dart
class A {
static int x = 3;
}
class B extends A {
int get g => A.x;
}
```
UNQUALIFIED_REFERENCE_TO_STATIC_MEMBER_OF_EXTENDED_TYPE:
problemMessage: Static members from the extended type or one of its superclasses must be qualified by the name of the defining type.
correctionMessage: "Try adding '{0}.' before the name."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the defining type
documentation: |-
#### Description
The analyzer produces this diagnostic when an undefined name is found, and
the name is the same as a static member of the extended type or one of its
superclasses.
#### Example
The following code produces this diagnostic because `m` is a static member
of the extended type `C`:
```dart
class C {
static void m() {}
}
extension E on C {
void f() {
[!m!]();
}
}
```
#### Common fixes
If you're trying to reference a static member that's declared outside the
extension, then add the name of the class or extension before the reference
to the member:
```dart
class C {
static void m() {}
}
extension E on C {
void f() {
C.m();
}
}
```
If you're referencing a member that isn't declared yet, add a declaration:
```dart
class C {
static void m() {}
}
extension E on C {
void f() {
m();
}
void m() {}
}
```
URI_DOES_NOT_EXIST:
problemMessage: "Target of URI doesn't exist: '{0}'."
correctionMessage: Try creating the file referenced by the URI, or try using a URI for a file that does exist.
hasPublishedDocs: true
comment: |-
Parameters:
0: the URI pointing to a nonexistent file
documentation: |-
#### Description
The analyzer produces this diagnostic when an import, export, or part
directive is found where the URI refers to a file that doesn't exist.
#### Example
If the file `lib.dart` doesn't exist, the following code produces this
diagnostic:
```dart
import [!'lib.dart'!];
```
#### Common fixes
If the URI was mistyped or invalid, then correct the URI.
If the URI is correct, then create the file.
URI_HAS_NOT_BEEN_GENERATED:
problemMessage: "Target of URI hasn't been generated: '{0}'."
correctionMessage: Try running the generator that will generate the file referenced by the URI.
hasPublishedDocs: true
comment: |-
Parameters:
0: the URI pointing to a nonexistent file
documentation: |-
#### Description
The analyzer produces this diagnostic when an import, export, or part
directive is found where the URI refers to a file that doesn't exist and
the name of the file ends with a pattern that's commonly produced by code
generators, such as one of the following:
- `.g.dart`
- `.pb.dart`
- `.pbenum.dart`
- `.pbserver.dart`
- `.pbjson.dart`
- `.template.dart`
#### Example
If the file `lib.g.dart` doesn't exist, the following code produces this
diagnostic:
```dart
import [!'lib.g.dart'!];
```
#### Common fixes
If the file is a generated file, then run the generator that generates the
file.
If the file isn't a generated file, then check the spelling of the URI or
create the file.
URI_WITH_INTERPOLATION:
problemMessage: "URIs can't use string interpolation."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the string literal in an
`import`, `export`, or `part` directive contains an interpolation. The
resolution of the URIs in directives must happen before the declarations
are compiled, so expressions can't be evaluated while determining the
values of the URIs.
#### Example
The following code produces this diagnostic because the string in the
`import` directive contains an interpolation:
```dart
import [!'dart:$m'!];
const m = 'math';
```
#### Common fixes
Remove the interpolation from the URI:
```dart
import 'dart:math';
var zero = min(0, 0);
```
USE_OF_NATIVE_EXTENSION:
problemMessage: Dart native extensions are deprecated and aren't available in Dart 2.15.
correctionMessage: "Try using dart:ffi for C interop."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a library is imported using the
`dart-ext` scheme.
#### Example
The following code produces this diagnostic because the native library `x`
is being imported using a scheme of `dart-ext`:
```dart
import [!'dart-ext:x'!];
```
#### Common fixes
Rewrite the code to use `dart:ffi` as a way of invoking the contents of the
native library.
USE_OF_VOID_RESULT:
problemMessage: "This expression has a type of 'void' so its value can't be used."
correctionMessage: "Try checking to see if you're using the correct API; there might be a function or call that returns void you didn't expect. Also check type parameters and variables which might also be void."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when it finds an expression whose
type is `void`, and the expression is used in a place where a value is
expected, such as before a member access or on the right-hand side of an
assignment.
#### Example
The following code produces this diagnostic because `f` doesn't produce an
object on which `toString` can be invoked:
```dart
void f() {}
void g() {
[!f()!].toString();
}
```
#### Common fixes
Either rewrite the code so that the expression has a value or rewrite the
code so that it doesn't depend on the value.
VALUES_DECLARATION_IN_ENUM:
problemMessage: A member named 'values' can't be declared in an enum.
correctionMessage: Try using a different name.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when an enum declaration defines a
member named `values`, whether the member is an enum constant, an instance
member, or a static member.
Any such member conflicts with the implicit declaration of the static
getter named `values` that returns a list containing all the enum
constants.
#### Example
The following code produces this diagnostic because the enum `E` defines
an instance member named `values`:
```dart
enum E {
v;
void [!values!]() {}
}
```
#### Common fixes
Change the name of the conflicting member:
```dart
enum E {
v;
void getValues() {}
}
```
VARIABLE_TYPE_MISMATCH:
problemMessage: "A value of type '{0}' can't be assigned to a const variable of type '{1}'."
correctionMessage: "Try using a subtype, or removing the 'const' keyword"
hasPublishedDocs: true
comment: |-
Parameters:
0: the type of the object being assigned.
1: the type of the variable being assigned to
documentation: |-
#### Description
The analyzer produces this diagnostic when the evaluation of a constant
expression would result in a `CastException`.
#### Example
The following code produces this diagnostic because the value of `x` is an
`int`, which can't be assigned to `y` because an `int` isn't a `String`:
```dart
%language=2.9
const Object x = 0;
const String y = [!x!];
```
#### Common fixes
If the declaration of the constant is correct, then change the value being
assigned to be of the correct type:
```dart
%language=2.9
const Object x = 0;
const String y = '$x';
```
If the assigned value is correct, then change the declaration to have the
correct type:
```dart
%language=2.9
const Object x = 0;
const int y = x;
```
WRONG_EXPLICIT_TYPE_PARAMETER_VARIANCE_IN_SUPERINTERFACE:
problemMessage: "'{0}' is an '{1}' type parameter and can't be used in an '{2}' position in '{3}'."
correctionMessage: "Try using 'in' type parameters in 'in' positions and 'out' type parameters in 'out' positions in the superinterface."
comment: |-
Let `C` be a generic class that declares a formal type parameter `X`, and
assume that `T` is a direct superinterface of `C`.
It is a compile-time error if `X` is explicitly defined as a covariant or
'in' type parameter and `X` occurs in a non-covariant position in `T`.
It is a compile-time error if `X` is explicitly defined as a contravariant
or 'out' type parameter and `X` occurs in a non-contravariant position in
`T`.
Parameters:
0: the name of the type parameter
1: the variance modifier defined for {0}
2: the variance position of the type parameter {0} in the
superinterface {3}
3: the name of the superinterface
WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR:
problemMessage: "Operator '{0}' should declare exactly {1} parameters, but {2} found."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the declared operator
1: the number of parameters expected
2: the number of parameters found in the operator declaration
documentation: |-
#### Description
The analyzer produces this diagnostic when a declaration of an operator has
the wrong number of parameters.
#### Example
The following code produces this diagnostic because the operator `+` must
have a single parameter corresponding to the right operand:
```dart
class C {
int operator [!+!](a, b) => 0;
}
```
#### Common fixes
Add or remove parameters to match the required number:
```dart
class C {
int operator +(a) => 0;
}
```
TODO(brianwilkerson) It would be good to add a link to the spec or some
other documentation that lists the number of parameters for each
operator, but I don't know what to link to.
TODO(brianwilkerson) Another reasonable fix is to convert the operator to
be a normal method.
WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR_MINUS:
sharedName: WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
problemMessage: "Operator '-' should declare 0 or 1 parameter, but {0} found."
hasPublishedDocs: true
comment: |-
7.1.1 Operators: It is a compile time error if the arity of the
user-declared operator - is not 0 or 1.
Parameters:
0: the number of parameters found in the operator declaration
WRONG_NUMBER_OF_PARAMETERS_FOR_SETTER:
problemMessage: Setters must declare exactly one required positional parameter.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a setter is found that doesn't
declare exactly one required positional parameter.
#### Examples
The following code produces this diagnostic because the setter `s` declares
two required parameters:
```dart
%language=2.9
class C {
set [!s!](int x, int y) {}
}
```
The following code produces this diagnostic because the setter `s` declares
one optional parameter:
```dart
%language=2.9
class C {
set [!s!]([int x]) {}
}
```
#### Common fixes
Change the declaration so that there's exactly one required positional
parameter:
```dart
%language=2.9
class C {
set s(int x) {}
}
```
WRONG_NUMBER_OF_TYPE_ARGUMENTS:
problemMessage: "The type '{0}' is declared with {1} type parameters, but {2} type arguments were given."
correctionMessage: Try adjusting the number of type arguments to match the number of type parameters.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the type being referenced (<i>G</i>)
1: the number of type parameters that were declared
2: the number of type arguments provided
documentation: |-
#### Description
The analyzer produces this diagnostic when a type that has type parameters
is used and type arguments are provided, but the number of type arguments
isn't the same as the number of type parameters.
The analyzer also produces this diagnostic when a constructor is invoked
and the number of type arguments doesn't match the number of type
parameters declared for the class.
#### Examples
The following code produces this diagnostic because `C` has one type
parameter but two type arguments are provided when it is used as a type
annotation:
```dart
class C<E> {}
void f([!C<int, int>!] x) {}
```
The following code produces this diagnostic because `C` declares one type
parameter, but two type arguments are provided when creating an instance:
```dart
class C<E> {}
var c = [!C<int, int>!]();
```
#### Common fixes
Add or remove type arguments, as necessary, to match the number of type
parameters defined for the type:
```dart
class C<E> {}
void f(C<int> x) {}
```
WRONG_NUMBER_OF_TYPE_ARGUMENTS_CONSTRUCTOR:
problemMessage: "The constructor '{0}.{1}' doesn't have type parameters."
correctionMessage: Try moving type arguments to after the type name.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the class being instantiated
1: the name of the constructor being invoked
documentation: |-
#### Description
The analyzer produces this diagnostic when type arguments are provided
after the name of a named constructor. Constructors can't declare type
parameters, so invocations can only provide the type arguments associated
with the class, and those type arguments are required to follow the name of
the class rather than the name of the constructor.
#### Example
The following code produces this diagnostic because the type parameters
(`<String>`) follow the name of the constructor rather than the name of the
class:
```dart
class C<T> {
C.named();
}
C f() => C.named[!<String>!]();
```
#### Common fixes
If the type arguments are for the class' type parameters, then move the
type arguments to follow the class name:
```dart
class C<T> {
C.named();
}
C f() => C<String>.named();
```
If the type arguments aren't for the class' type parameters, then remove
them:
```dart
class C<T> {
C.named();
}
C f() => C.named();
```
WRONG_NUMBER_OF_TYPE_ARGUMENTS_ENUM:
problemMessage: The enum is declared with {0} type parameters, but {1} type arguments were given.
correctionMessage: Try adjusting the number of type arguments.
hasPublishedDocs: true
comment: |-
Parameters:
0: the number of type parameters that were declared
1: the number of type arguments provided
documentation: |-
#### Description
The analyzer produces this diagnostic when an enum constant in an enum
that has type parameters is instantiated and type arguments are provided,
but the number of type arguments isn't the same as the number of type
parameters.
#### Example
The following code produces this diagnostic because the enum constant `c`
provides one type argument even though the enum `E` is declared to have
two type parameters:
```dart
enum E<T, U> {
c[!<int>!]()
}
```
#### Common fixes
If the number of type parameters is correct, then change the number of
type arguments to match the number of type parameters:
```dart
enum E<T, U> {
c<int, String>()
}
```
If the number of type arguments is correct, then change the number of type
parameters to match the number of type arguments:
```dart
enum E<T> {
c<int>()
}
```
WRONG_NUMBER_OF_TYPE_ARGUMENTS_EXTENSION:
problemMessage: "The extension '{0}' is declared with {1} type parameters, but {2} type arguments were given."
correctionMessage: Try adjusting the number of type arguments.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the extension being referenced
1: the number of type parameters that were declared
2: the number of type arguments provided
documentation: |-
#### Description
The analyzer produces this diagnostic when an extension that has type
parameters is used and type arguments are provided, but the number of type
arguments isn't the same as the number of type parameters.
#### Example
The following code produces this diagnostic because the extension `E` is
declared to have a single type parameter (`T`), but the extension override
has two type arguments:
```dart
extension E<T> on List<T> {
int get len => length;
}
void f(List<int> p) {
E[!<int, String>!](p).len;
}
```
#### Common fixes
Change the type arguments so that there are the same number of type
arguments as there are type parameters:
```dart
extension E<T> on List<T> {
int get len => length;
}
void f(List<int> p) {
E<int>(p).len;
}
```
WRONG_NUMBER_OF_TYPE_ARGUMENTS_ANONYMOUS_FUNCTION:
sharedName: WRONG_NUMBER_OF_TYPE_ARGUMENTS_FUNCTION
problemMessage: "This function is declared with {0} type parameters, but {1} type arguments were given."
correctionMessage: Try adjusting the number of type arguments to match the number of type parameters.
comment: |-
Parameters:
0: the number of type parameters that were declared
1: the number of type arguments provided
WRONG_NUMBER_OF_TYPE_ARGUMENTS_FUNCTION:
problemMessage: "The function '{0}' is declared with {1} type parameters, but {2} type arguments were given."
correctionMessage: Try adjusting the number of type arguments to match the number of type parameters.
comment: |-
Parameters:
0: the name of the function being referenced
1: the number of type parameters that were declared
2: the number of type arguments provided
WRONG_NUMBER_OF_TYPE_ARGUMENTS_METHOD:
problemMessage: "The method '{0}' is declared with {1} type parameters, but {2} type arguments are given."
correctionMessage: Try adjusting the number of type arguments.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the method being referenced (<i>G</i>)
1: the number of type parameters that were declared
2: the number of type arguments provided
documentation: |-
#### Description
The analyzer produces this diagnostic when a method or function is invoked
with a different number of type arguments than the number of type
parameters specified in its declaration. There must either be no type
arguments or the number of arguments must match the number of parameters.
#### Example
The following code produces this diagnostic because the invocation of the
method `m` has two type arguments, but the declaration of `m` only has one
type parameter:
```dart
class C {
int m<A>(A a) => 0;
}
int f(C c) => c.m[!<int, int>!](2);
```
#### Common fixes
If the type arguments are necessary, then make them match the number of
type parameters by either adding or removing type arguments:
```dart
class C {
int m<A>(A a) => 0;
}
int f(C c) => c.m<int>(2);
```
If the type arguments aren't necessary, then remove them:
```dart
class C {
int m<A>(A a) => 0;
}
int f(C c) => c.m(2);
```
WRONG_TYPE_PARAMETER_VARIANCE_IN_SUPERINTERFACE:
problemMessage: "'{0}' can't be used contravariantly or invariantly in '{1}'."
correctionMessage: Try not using class type parameters in types of formal parameters of function types, nor in explicitly contravariant or invariant superinterfaces.
comment: |-
Let `C` be a generic class that declares a formal type parameter `X`, and
assume that `T` is a direct superinterface of `C`. It is a compile-time
error if `X` occurs contravariantly or invariantly in `T`.
Parameters:
0: the name of the type parameter
1: the name of the super interface
WRONG_TYPE_PARAMETER_VARIANCE_POSITION:
problemMessage: "The '{0}' type parameter '{1}' can't be used in an '{2}' position."
correctionMessage: "Try removing the type parameter or change the explicit variance modifier declaration for the type parameter to another one of 'in', 'out', or 'inout'."
comment: |-
Let `C` be a generic class that declares a formal type parameter `X`.
If `X` is explicitly contravariant then it is a compile-time error for
`X` to occur in a non-contravariant position in a member signature in the
body of `C`, except when `X` is in a contravariant position in the type
annotation of a covariant formal parameter.
If `X` is explicitly covariant then it is a compile-time error for
`X` to occur in a non-covariant position in a member signature in the
body of `C`, except when `X` is in a covariant position in the type
annotation of a covariant formal parameter.
Parameters:
0: the variance modifier defined for {0}
1: the name of the type parameter
2: the variance position that the type parameter {1} is in
YIELD_EACH_IN_NON_GENERATOR:
sharedName: YIELD_IN_NON_GENERATOR
problemMessage: "Yield-each statements must be in a generator function (one marked with either 'async*' or 'sync*')."
correctionMessage: "Try adding 'async*' or 'sync*' to the enclosing function."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a `yield` or `yield*` statement
appears in a function whose body isn't marked with one of the `async*` or
`sync*` modifiers.
#### Examples
The following code produces this diagnostic because `yield` is being used
in a function whose body doesn't have a modifier:
```dart
Iterable<int> get digits {
yield* [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
}
```
The following code produces this diagnostic because `yield*` is being used
in a function whose body has the `async` modifier rather than the `async*`
modifier:
```dart
Stream<int> get digits async {
yield* [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
}
```
#### Common fixes
Add a modifier, or change the existing modifier to be either `async*` or
`sync*`:
```dart
Iterable<int> get digits sync* {
yield* [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
}
```
YIELD_IN_NON_GENERATOR:
problemMessage: "Yield statements must be in a generator function (one marked with either 'async*' or 'sync*')."
correctionMessage: "Try adding 'async*' or 'sync*' to the enclosing function."
hasPublishedDocs: true
comment: |-
?? Yield: It is a compile-time error if a yield statement appears in a
function that is not a generator function.
No parameters.
YIELD_EACH_OF_INVALID_TYPE:
sharedName: YIELD_OF_INVALID_TYPE
problemMessage: "The type '{0}' implied by the 'yield*' expression must be assignable to '{1}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the type of the expression after `yield*`
1: the return type of the function containing the `yield*`
YIELD_OF_INVALID_TYPE:
problemMessage: "A yielded value of type '{0}' must be assignable to '{1}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the type of the expression after `yield`
1: the return type of the function containing the `yield`
documentation: |-
#### Description
The analyzer produces this diagnostic when the type of object produced by
a `yield` or `yield*` expression doesn't match the type of objects that
are to be returned from the `Iterable` or `Stream` types that are returned
from a generator (a function or method marked with either `sync*` or
`async*`).
#### Example
The following code produces this diagnostic because the getter `zero` is
declared to return an `Iterable` that returns integers, but the `yield` is
returning a string from the iterable:
```dart
Iterable<int> get zero sync* {
yield [!'0'!];
}
```
#### Common fixes
If the return type of the function is correct, then fix the expression
following the keyword `yield` to return the correct type:
```dart
Iterable<int> get zero sync* {
yield 0;
}
```
If the expression following the `yield` is correct, then change the return
type of the function to allow it:
```dart
Iterable<String> get zero sync* {
yield '0';
}
```
FfiCode:
ABI_SPECIFIC_INTEGER_INVALID:
problemMessage: "Classes extending 'AbiSpecificInteger' must have exactly one const constructor, no other members, and no type parameters."
correctionMessage: Try removing all type parameters, removing all members, and adding one const constructor.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a class that extends
`AbiSpecificInteger` doesn't meet all of the following requirements:
- there must be exactly one constructor
- the constructor must be marked `const`
- there must not be any members of other than the one constructor
- there must not be any type parameters
#### Examples
The following code produces this diagnostic because the class `C` doesn't
define a const constructor:
```dart
import 'dart:ffi';
@AbiSpecificIntegerMapping({Abi.macosX64 : Int8()})
final class [!C!] extends AbiSpecificInteger {
}
```
The following code produces this diagnostic because the constructor isn't
a `const` constructor:
```dart
import 'dart:ffi';
@AbiSpecificIntegerMapping({Abi.macosX64 : Int8()})
final class [!C!] extends AbiSpecificInteger {
C();
}
```
The following code produces this diagnostic because the class `C` defines
multiple constructors:
```dart
import 'dart:ffi';
@AbiSpecificIntegerMapping({Abi.macosX64 : Int8()})
final class [!C!] extends AbiSpecificInteger {
const C.zero();
const C.one();
}
```
The following code produces this diagnostic because the class `C` defines
a field:
```dart
import 'dart:ffi';
@AbiSpecificIntegerMapping({Abi.macosX64 : Int8()})
final class [!C!] extends AbiSpecificInteger {
final int i;
const C(this.i);
}
```
The following code produces this diagnostic because the class `C` has a
type parameter:
```dart
import 'dart:ffi';
@AbiSpecificIntegerMapping({Abi.macosX64 : Int8()})
final class [!C!]<T> extends AbiSpecificInteger { // type parameters
const C();
}
```
#### Common fixes
Change the class so that it meets the requirements of having no type
parameters and a single member that is a `const` constructor:
```dart
import 'dart:ffi';
@AbiSpecificIntegerMapping({Abi.macosX64 : Int8()})
final class C extends AbiSpecificInteger {
const C();
}
```
ABI_SPECIFIC_INTEGER_MAPPING_EXTRA:
problemMessage: "Classes extending 'AbiSpecificInteger' must have exactly one 'AbiSpecificIntegerMapping' annotation specifying the mapping from ABI to a 'NativeType' integer with a fixed size."
correctionMessage: Try removing the extra annotation.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a class that extends
`AbiSpecificInteger` has more than one `AbiSpecificIntegerMapping`
annotation.
#### Example
The following code produces this diagnostic because there are two
`AbiSpecificIntegerMapping` annotations on the class `C`:
```dart
import 'dart:ffi';
@AbiSpecificIntegerMapping({Abi.macosX64 : Int8()})
@[!AbiSpecificIntegerMapping!]({Abi.linuxX64 : Uint16()})
final class C extends AbiSpecificInteger {
const C();
}
```
#### Common fixes
Remove all but one of the annotations, merging the arguments as
appropriate:
```dart
import 'dart:ffi';
@AbiSpecificIntegerMapping({Abi.macosX64 : Int8(), Abi.linuxX64 : Uint16()})
final class C extends AbiSpecificInteger {
const C();
}
```
ABI_SPECIFIC_INTEGER_MAPPING_MISSING:
problemMessage: "Classes extending 'AbiSpecificInteger' must have exactly one 'AbiSpecificIntegerMapping' annotation specifying the mapping from ABI to a 'NativeType' integer with a fixed size."
correctionMessage: Try adding an annotation.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a class that extends
`AbiSpecificInteger` doesn't have an `AbiSpecificIntegerMapping`
annotation.
#### Example
The following code produces this diagnostic because there's no
`AbiSpecificIntegerMapping` annotation on the class `C`:
```dart
import 'dart:ffi';
final class [!C!] extends AbiSpecificInteger {
const C();
}
```
#### Common fixes
Add an `AbiSpecificIntegerMapping` annotation to the class:
```dart
import 'dart:ffi';
@AbiSpecificIntegerMapping({Abi.macosX64 : Int8()})
final class C extends AbiSpecificInteger {
const C();
}
```
ABI_SPECIFIC_INTEGER_MAPPING_UNSUPPORTED:
problemMessage: "Invalid mapping to '{0}'; only mappings to 'Int8', 'Int16', 'Int32', 'Int64', 'Uint8', 'Uint16', 'UInt32', and 'Uint64' are supported."
correctionMessage: Try changing the value to 'Int8', 'Int16', 'Int32', 'Int64', 'Uint8', 'Uint16', 'UInt32', or 'Uint64'.
hasPublishedDocs: true
comment: |-
Parameters:
0: the value of the invalid mapping
documentation: |-
#### Description
The analyzer produces this diagnostic when a value in the map argument of
an `AbiSpecificIntegerMapping` annotation is anything other than one of
the following integer types:
- `Int8`
- `Int16`
- `Int32`
- `Int64`
- `Uint8`
- `Uint16`
- `UInt32`
- `Uint64`
#### Example
The following code produces this diagnostic because the value of the map
entry is `Array<Uint8>`, which isn't a valid integer type:
```dart
import 'dart:ffi';
@AbiSpecificIntegerMapping({Abi.macosX64 : [!Array<Uint8>(4)!]})
final class C extends AbiSpecificInteger {
const C();
}
```
#### Common fixes
Use one of the valid types as a value in the map:
```dart
import 'dart:ffi';
@AbiSpecificIntegerMapping({Abi.macosX64 : Int8()})
final class C extends AbiSpecificInteger {
const C();
}
```
ANNOTATION_ON_POINTER_FIELD:
problemMessage: "Fields in a struct class whose type is 'Pointer' shouldn't have any annotations."
correctionMessage: Try removing the annotation.
comment: No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a field that's declared in a
subclass of `Struct` and has the type `Pointer` also has an annotation
associated with it.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the field `p`, which
has the type `Pointer` and is declared in a subclass of `Struct`, has the
annotation `@Double()`:
```dart
import 'dart:ffi';
final class C extends Struct {
[!@Double()!]
external Pointer<Int8> p;
}
```
#### Common fixes
Remove the annotations from the field:
```dart
import 'dart:ffi';
final class C extends Struct {
external Pointer<Int8> p;
}
```
ARGUMENT_MUST_BE_A_CONSTANT:
problemMessage: "Argument '{0}' must be a constant."
correctionMessage: Try replacing the value with a literal or const.
comment: |-
Parameters:
0: the name of the argument
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when an invocation of either
`Pointer.asFunction` or `DynamicLibrary.lookupFunction` has an `isLeaf`
argument whose value isn't a constant expression.
The analyzer also produces this diagnostic when the value of the
`exceptionalReturn` argument of `Pointer.fromFunction`.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the value of the
`isLeaf` argument is a parameter, and hence isn't a constant:
```dart
import 'dart:ffi';
int Function(int) fromPointer(
Pointer<NativeFunction<Int8 Function(Int8)>> p, bool isLeaf) {
return p.asFunction(isLeaf: [!isLeaf!]);
}
```
#### Common fixes
If there's a suitable constant that can be used, then replace the argument
with a constant:
```dart
import 'dart:ffi';
const isLeaf = false;
int Function(int) fromPointer(Pointer<NativeFunction<Int8 Function(Int8)>> p) {
return p.asFunction(isLeaf: isLeaf);
}
```
If there isn't a suitable constant, then replace the argument with a
boolean literal:
```dart
import 'dart:ffi';
int Function(int) fromPointer(Pointer<NativeFunction<Int8 Function(Int8)>> p) {
return p.asFunction(isLeaf: true);
}
```
COMPOUND_IMPLEMENTS_FINALIZABLE:
problemMessage: "The class '{0}' can't implement Finalizable."
correctionMessage: "Try removing the implements clause from '{0}'."
comment: |-
Parameters:
0: the name of the struct or union class
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a subclass of either `Struct`
or `Union` implements `Finalizable`.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the class `S`
implements `Finalizable`:
```dart
import 'dart:ffi';
final class [!S!] extends Struct implements Finalizable {
external Pointer notEmpty;
}
```
#### Common fixes
Try removing the implements clause from the class:
```dart
import 'dart:ffi';
final class S extends Struct {
external Pointer notEmpty;
}
```
CREATION_OF_STRUCT_OR_UNION:
problemMessage: "Subclasses of 'Struct' and 'Union' are backed by native memory, and can't be instantiated by a generative constructor."
correctionMessage: "Try allocating it via allocation, or load from a 'Pointer'."
comment: No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a subclass of either `Struct`
or `Union` is instantiated using a generative constructor.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the class `C` is being
instantiated using a generative constructor:
```dart
import 'dart:ffi';
final class C extends Struct {
@Int32()
external int a;
}
void f() {
[!C!]();
}
```
#### Common fixes
If you need to allocate the structure described by the class, then use the
`ffi` package to do so:
```dart
import 'dart:ffi';
import 'package:ffi/ffi.dart';
final class C extends Struct {
@Int32()
external int a;
}
void f() {
final pointer = calloc.allocate<C>(4);
final c = pointer.ref;
print(c);
calloc.free(pointer);
}
```
EMPTY_STRUCT:
problemMessage: "The class '{0}' can't be empty because it's a subclass of '{1}'."
correctionMessage: "Try adding a field to '{0}' or use a different superclass."
comment: |-
Parameters:
0: the name of the subclass
1: the name of the superclass
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a subclass of `Struct` or
`Union` doesn't have any fields. Having an empty `Struct` or `Union`
isn't supported.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the class `C`, which
extends `Struct`, doesn't declare any fields:
```dart
import 'dart:ffi';
final class [!C!] extends Struct {}
```
#### Common fixes
If the class is intended to be a struct, then declare one or more fields:
```dart
import 'dart:ffi';
final class C extends Struct {
@Int32()
external int x;
}
```
If the class is intended to be used as a type argument to `Pointer`, then
make it a subclass of `Opaque`:
```dart
import 'dart:ffi';
final class C extends Opaque {}
```
If the class isn't intended to be a struct, then remove or change the
extends clause:
```dart
class C {}
```
EXTRA_ANNOTATION_ON_STRUCT_FIELD:
problemMessage: Fields in a struct class must have exactly one annotation indicating the native type.
correctionMessage: Try removing the extra annotation.
comment: No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a field in a subclass of
`Struct` has more than one annotation describing the native type of the
field.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the field `x` has two
annotations describing the native type of the field:
```dart
import 'dart:ffi';
final class C extends Struct {
@Int32()
[!@Int16()!]
external int x;
}
```
#### Common fixes
Remove all but one of the annotations:
```dart
import 'dart:ffi';
final class C extends Struct {
@Int32()
external int x;
}
```
EXTRA_SIZE_ANNOTATION_CARRAY:
problemMessage: "'Array's must have exactly one 'Array' annotation."
correctionMessage: Try removing the extra annotation.
comment: No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a field in a subclass of
`Struct` has more than one annotation describing the size of the native
array.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the field `a0` has two
annotations that specify the size of the native array:
```dart
import 'dart:ffi';
final class C extends Struct {
@Array(4)
[!@Array(8)!]
external Array<Uint8> a0;
}
```
#### Common fixes
Remove all but one of the annotations:
```dart
import 'dart:ffi';
final class C extends Struct {
@Array(8)
external Array<Uint8> a0;
}
```
FFI_NATIVE_MUST_BE_EXTERNAL:
problemMessage: FfiNative functions must be declared external.
correctionMessage: Add the `external` keyword to the function.
comment: No parameters.
FFI_NATIVE_ONLY_CLASSES_EXTENDING_NATIVEFIELDWRAPPERCLASS1_CAN_BE_POINTER:
problemMessage: Only classes extending NativeFieldWrapperClass1 can be passed as Pointer.
correctionMessage: Pass as Handle instead.
comment: No parameters.
FFI_NATIVE_UNEXPECTED_NUMBER_OF_PARAMETERS:
problemMessage: Unexpected number of FfiNative annotation parameters. Expected {0} but has {1}.
correctionMessage: Make sure parameters match the function annotated.
comment: |-
Parameters:
0: the expected number of parameters
1: the actual number of parameters
FFI_NATIVE_UNEXPECTED_NUMBER_OF_PARAMETERS_WITH_RECEIVER:
problemMessage: Unexpected number of FfiNative annotation parameters. Expected {0} but has {1}. FfiNative instance method annotation must have receiver as first argument.
correctionMessage: Make sure parameters match the function annotated, including an extra first parameter for the receiver.
comment: |-
Parameters:
0: the expected number of parameters
1: the actual number of parameters
FIELD_INITIALIZER_IN_STRUCT:
problemMessage: "Constructors in subclasses of 'Struct' and 'Union' can't have field initializers."
correctionMessage: Try removing the field initializer and marking the field as external.
comment: No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a constructor in a subclass of
either `Struct` or `Union` has one or more field initializers.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the class `C` has a
constructor with an initializer for the field `f`:
```dart
// @dart = 2.9
import 'dart:ffi';
final class C extends Struct {
@Int32()
int f;
C() : [!f = 0!];
}
```
#### Common fixes
Remove the field initializer:
```dart
// @dart = 2.9
import 'dart:ffi';
final class C extends Struct {
@Int32()
int f;
C();
}
```
FIELD_IN_STRUCT_WITH_INITIALIZER:
problemMessage: "Fields in subclasses of 'Struct' and 'Union' can't have initializers."
correctionMessage: Try removing the initializer and marking the field as external.
comment: No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a field in a subclass of
`Struct` has an initializer.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the field `p` has an
initializer:
```dart
// @dart = 2.9
import 'dart:ffi';
final class C extends Struct {
Pointer [!p!] = nullptr;
}
```
#### Common fixes
Remove the initializer:
```dart
// @dart = 2.9
import 'dart:ffi';
final class C extends Struct {
Pointer p;
}
```
FIELD_MUST_BE_EXTERNAL_IN_STRUCT:
problemMessage: "Fields of 'Struct' and 'Union' subclasses must be marked external."
correctionMessage: "Try adding the 'external' modifier."
comment: No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a field in a subclass of either
`Struct` or `Union` isn't marked as being `external`.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the field `a` isn't
marked as being `external`:
```dart
import 'dart:ffi';
final class C extends Struct {
@Int16()
int [!a!];
}
```
#### Common fixes
Add the required `external` modifier:
```dart
import 'dart:ffi';
final class C extends Struct {
@Int16()
external int a;
}
```
GENERIC_STRUCT_SUBCLASS:
problemMessage: "The class '{0}' can't extend 'Struct' or 'Union' because '{0}' is generic."
correctionMessage: "Try removing the type parameters from '{0}'."
comment: |-
Parameters:
0: the name of the struct class
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a subclass of either `Struct`
or `Union` has a type parameter.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the class `S` defines
the type parameter `T`:
```dart
import 'dart:ffi';
final class [!S!]<T> extends Struct {
external Pointer notEmpty;
}
```
#### Common fixes
Remove the type parameters from the class:
```dart
import 'dart:ffi';
final class S extends Struct {
external Pointer notEmpty;
}
```
INVALID_EXCEPTION_VALUE:
problemMessage: "The method 'Pointer.fromFunction' can't have an exceptional return value (the second argument) when the return type of the function is either 'void', 'Handle' or 'Pointer'."
correctionMessage: Try removing the exceptional return value.
comment: No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when an invocation of the method
`Pointer.fromFunction` has a second argument (the exceptional return
value) and the type to be returned from the invocation is either `void`,
`Handle` or `Pointer`.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because a second argument is
provided when the return type of `f` is `void`:
```dart
import 'dart:ffi';
typedef T = Void Function(Int8);
void f(int i) {}
void g() {
Pointer.fromFunction<T>(f, [!42!]);
}
```
#### Common fixes
Remove the exception value:
```dart
import 'dart:ffi';
typedef T = Void Function(Int8);
void f(int i) {}
void g() {
Pointer.fromFunction<T>(f);
}
```
INVALID_FIELD_TYPE_IN_STRUCT:
problemMessage: "Fields in struct classes can't have the type '{0}'. They can only be declared as 'int', 'double', 'Array', 'Pointer', or subtype of 'Struct' or 'Union'."
correctionMessage: "Try using 'int', 'double', 'Array', 'Pointer', or subtype of 'Struct' or 'Union'."
comment: |-
Parameters:
0: the type of the field
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a field in a subclass of
`Struct` has a type other than `int`, `double`, `Array`, `Pointer`, or
subtype of `Struct` or `Union`.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the field `str` has
the type `String`, which isn't one of the allowed types for fields in a
subclass of `Struct`:
```dart
import 'dart:ffi';
final class C extends Struct {
external [!String!] s;
@Int32()
external int i;
}
```
#### Common fixes
Use one of the allowed types for the field:
```dart
import 'dart:ffi';
import 'package:ffi/ffi.dart';
final class C extends Struct {
external Pointer<Utf8> s;
@Int32()
external int i;
}
```
LEAF_CALL_MUST_NOT_RETURN_HANDLE:
problemMessage: "FFI leaf call can't return a 'Handle'."
correctionMessage: Try changing the return type to primitive or struct.
comment: No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when the value of the `isLeaf`
argument in an invocation of either `Pointer.asFunction` or
`DynamicLibrary.lookupFunction` is `true` and the function that would be
returned would have a return type of `Handle`.
The analyzer also produces this diagnostic when the value of the `isLeaf`
argument in an `FfiNative` annotation is `true` and the type argument on
the annotation is a function type whose return type is `Handle`.
In all of these cases, leaf calls are only supported for the types `bool`,
`int`, `float`, `double`, and, as a return type `void`.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the function `p`
returns a `Handle`, but the `isLeaf` argument is `true`:
```dart
import 'dart:ffi';
void f(Pointer<NativeFunction<Handle Function()>> p) {
[!p.asFunction<Object Function()>(isLeaf: true)!];
}
```
#### Common fixes
If the function returns a handle, then remove the `isLeaf` argument:
```dart
import 'dart:ffi';
void f(Pointer<NativeFunction<Handle Function()>> p) {
p.asFunction<Object Function()>();
}
```
If the function returns one of the supported types, then correct the type
information:
```dart
import 'dart:ffi';
void f(Pointer<NativeFunction<Int32 Function()>> p) {
p.asFunction<int Function()>(isLeaf: true);
}
```
LEAF_CALL_MUST_NOT_TAKE_HANDLE:
problemMessage: "FFI leaf call can't take arguments of type 'Handle'."
correctionMessage: Try changing the argument type to primitive or struct.
comment: No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when the value of the `isLeaf`
argument in an invocation of either `Pointer.asFunction` or
`DynamicLibrary.lookupFunction` is `true` and the function that would be
returned would have a parameter of type `Handle`.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the function `p` has a
parameter of type `Handle`, but the `isLeaf` argument is `true`:
```dart
import 'dart:ffi';
void f(Pointer<NativeFunction<Void Function(Handle)>> p) {
[!p.asFunction<void Function(Object)>(isLeaf: true)!];
}
```
#### Common fixes
If the function has at least one parameter of type `Handle`, then remove
the `isLeaf` argument:
```dart
import 'dart:ffi';
void f(Pointer<NativeFunction<Void Function(Handle)>> p) {
p.asFunction<void Function(Object)>();
}
```
If none of the function's parameters are `Handle`s, then correct the type
information:
```dart
import 'dart:ffi';
void f(Pointer<NativeFunction<Void Function(Int8)>> p) {
p.asFunction<void Function(int)>(isLeaf: true);
}
```
MISMATCHED_ANNOTATION_ON_STRUCT_FIELD:
problemMessage: "The annotation doesn't match the declared type of the field."
correctionMessage: Try using a different annotation or changing the declared type to match.
comment: No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when the annotation on a field in a
subclass of `Struct` or `Union` doesn't match the Dart type of the field.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the annotation
`Double` doesn't match the Dart type `int`:
```dart
import 'dart:ffi';
final class C extends Struct {
[!@Double()!]
external int x;
}
```
#### Common fixes
If the type of the field is correct, then change the annotation to match:
```dart
import 'dart:ffi';
final class C extends Struct {
@Int32()
external int x;
}
```
If the annotation is correct, then change the type of the field to match:
```dart
import 'dart:ffi';
final class C extends Struct {
@Double()
external double x;
}
```
MISSING_ANNOTATION_ON_STRUCT_FIELD:
problemMessage: "Fields of type '{0}' in a subclass of '{1}' must have an annotation indicating the native type."
correctionMessage: Try adding an annotation.
comment: |-
Parameters:
0: the type that is missing a native type annotation
1: the superclass which is extended by this field's class
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a field in a subclass of
`Struct` or `Union` whose type requires an annotation doesn't have one.
The Dart types `int`, `double`, and `Array` are used to represent multiple
C types, and the annotation specifies which of the compatible C types the
field represents.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the field `x` doesn't
have an annotation indicating the underlying width of the integer value:
```dart
import 'dart:ffi';
final class C extends Struct {
external [!int!] x;
}
```
#### Common fixes
Add an appropriate annotation to the field:
```dart
import 'dart:ffi';
final class C extends Struct {
@Int64()
external int x;
}
```
MISSING_EXCEPTION_VALUE:
problemMessage: "The method 'Pointer.fromFunction' must have an exceptional return value (the second argument) when the return type of the function is neither 'void', 'Handle', nor 'Pointer'."
correctionMessage: Try adding an exceptional return value.
comment: No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when an invocation of the method
`Pointer.fromFunction` doesn't have a second argument (the exceptional
return value) when the type to be returned from the invocation is neither
`void`, `Handle`, nor `Pointer`.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the type returned by
`f` is expected to be an 8-bit integer but the call to `fromFunction`
doesn't include an exceptional return argument:
```dart
import 'dart:ffi';
int f(int i) => i * 2;
void g() {
Pointer.[!fromFunction!]<Int8 Function(Int8)>(f);
}
```
#### Common fixes
Add an exceptional return type:
```dart
import 'dart:ffi';
int f(int i) => i * 2;
void g() {
Pointer.fromFunction<Int8 Function(Int8)>(f, 0);
}
```
MISSING_FIELD_TYPE_IN_STRUCT:
problemMessage: "Fields in struct classes must have an explicitly declared type of 'int', 'double' or 'Pointer'."
correctionMessage: "Try using 'int', 'double' or 'Pointer'."
comment: No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a field in a subclass of
`Struct` or `Union` doesn't have a type annotation. Every field must have
an explicit type, and the type must either be `int`, `double`, `Pointer`,
or a subclass of either `Struct` or `Union`.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the field `str`
doesn't have a type annotation:
```dart
import 'dart:ffi';
final class C extends Struct {
external var [!str!];
@Int32()
external int i;
}
```
#### Common fixes
Explicitly specify the type of the field:
```dart
import 'dart:ffi';
import 'package:ffi/ffi.dart';
final class C extends Struct {
external Pointer<Utf8> str;
@Int32()
external int i;
}
```
MISSING_SIZE_ANNOTATION_CARRAY:
problemMessage: "Fields of type 'Array' must have exactly one 'Array' annotation."
correctionMessage: "Try adding an 'Array' annotation, or removing all but one of the annotations."
comment: No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a field in a subclass of either
`Struct` or `Union` has a type of `Array` but doesn't have a single
`Array` annotation indicating the dimensions of the array.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the field `a0` doesn't
have an `Array` annotation:
```dart
import 'dart:ffi';
final class C extends Struct {
external [!Array<Uint8>!] a0;
}
```
#### Common fixes
Ensure that there's exactly one `Array` annotation on the field:
```dart
import 'dart:ffi';
final class C extends Struct {
@Array(8)
external Array<Uint8> a0;
}
```
MUST_BE_A_NATIVE_FUNCTION_TYPE:
problemMessage: "The type '{0}' given to '{1}' must be a valid 'dart:ffi' native function type."
correctionMessage: "Try changing the type to only use members for 'dart:ffi'."
comment: |-
Parameters:
0: the type that should be a valid dart:ffi native type.
1: the name of the function whose invocation depends on this relationship
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when an invocation of either
`Pointer.fromFunction` or `DynamicLibrary.lookupFunction` has a type
argument(whether explicit or inferred) that isn't a native function type.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the type `T` can be
any subclass of `Function` but the type argument for `fromFunction` is
required to be a native function type:
```dart
import 'dart:ffi';
int f(int i) => i * 2;
class C<T extends Function> {
void g() {
Pointer.fromFunction<[!T!]>(f, 0);
}
}
```
#### Common fixes
Use a native function type as the type argument to the invocation:
```dart
import 'dart:ffi';
int f(int i) => i * 2;
class C<T extends Function> {
void g() {
Pointer.fromFunction<Int32 Function(Int32)>(f, 0);
}
}
```
MUST_BE_A_SUBTYPE:
problemMessage: "The type '{0}' must be a subtype of '{1}' for '{2}'."
correctionMessage: Try changing one or both of the type arguments.
comment: |-
Parameters:
0: the type that should be a subtype
1: the supertype that the subtype is compared to
2: the name of the function whose invocation depends on this relationship
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic in two cases:
- In an invocation of `Pointer.fromFunction` where the type argument
(whether explicit or inferred) isn't a supertype of the type of the
function passed as the first argument to the method.
- In an invocation of `DynamicLibrary.lookupFunction` where the first type
argument isn't a supertype of the second type argument.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the type of the
function `f` (`String Function(int)`) isn't a subtype of the type
argument `T` (`Int8 Function(Int8)`):
```dart
import 'dart:ffi';
typedef T = Int8 Function(Int8);
double f(double i) => i;
void g() {
Pointer.fromFunction<T>([!f!], 5.0);
}
```
#### Common fixes
If the function is correct, then change the type argument to match:
```dart
import 'dart:ffi';
typedef T = Float Function(Float);
double f(double i) => i;
void g() {
Pointer.fromFunction<T>(f, 5.0);
}
```
If the type argument is correct, then change the function to match:
```dart
import 'dart:ffi';
typedef T = Int8 Function(Int8);
int f(int i) => i;
void g() {
Pointer.fromFunction<T>(f, 5);
}
```
MUST_RETURN_VOID:
problemMessage: "The return type of the function passed to 'NativeCallable.listener' must be 'void' rather than '{0}'."
correctionMessage: "Try changing the return type to 'void'."
comment: |-
Parameters:
0: the return type that should be 'void'.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when you pass a function
that doesn't return `void` to the `NativeCallable.listener` constructor.
`NativeCallable.listener` creates a native callable that can be invoked
from any thread. The native code that invokes the callable sends a message
back to the isolate that created the callable, and doesn't wait for a
response. So it isn't possible to return a result from the callable.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the function
`f` returns `int` rather than `void`.
```dart
import 'dart:ffi';
int f(int i) => i * 2;
void g() {
NativeCallable<Int32 Function(Int32)>.listener([!f!]);
}
```
#### Common fixes
Change the return type of the function to `void`.
```dart
import 'dart:ffi';
void f(int i) => print(i * 2);
void g() {
NativeCallable<Void Function(Int32)>.listener(f);
}
```
NON_CONSTANT_TYPE_ARGUMENT:
problemMessage: "The type arguments to '{0}' must be known at compile time, so they can't be type parameters."
correctionMessage: Try changing the type argument to be a constant type.
comment: |-
Parameters:
0: the name of the function, method, or constructor having type arguments
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when the type arguments to a method
are required to be known at compile time, but a type parameter, whose
value can't be known at compile time, is used as a type argument.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the type argument to
`Pointer.asFunction` must be known at compile time, but the type parameter
`R`, which isn't known at compile time, is being used as the type
argument:
```dart
import 'dart:ffi';
typedef T = int Function(int);
class C<R extends T> {
void m(Pointer<NativeFunction<T>> p) {
p.asFunction<[!R!]>();
}
}
```
#### Common fixes
Remove any uses of type parameters:
```dart
import 'dart:ffi';
class C {
void m(Pointer<NativeFunction<Int64 Function(Int64)>> p) {
p.asFunction<int Function(int)>();
}
}
```
NON_NATIVE_FUNCTION_TYPE_ARGUMENT_TO_POINTER:
problemMessage: "Can't invoke 'asFunction' because the function signature '{0}' for the pointer isn't a valid C function signature."
correctionMessage: "Try changing the function argument in 'NativeFunction' to only use NativeTypes."
comment: |-
Parameters:
0: the type that should be a valid dart:ffi native type.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when the method `asFunction` is
invoked on a pointer to a native function, but the signature of the native
function isn't a valid C function signature.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because function signature
associated with the pointer `p` (`FNative`) isn't a valid C function
signature:
```dart
import 'dart:ffi';
typedef FNative = int Function(int);
typedef F = int Function(int);
class C {
void f(Pointer<NativeFunction<FNative>> p) {
p.asFunction<[!F!]>();
}
}
```
#### Common fixes
Make the `NativeFunction` signature a valid C signature:
```dart
import 'dart:ffi';
typedef FNative = Int8 Function(Int8);
typedef F = int Function(int);
class C {
void f(Pointer<NativeFunction<FNative>> p) {
p.asFunction<F>();
}
}
```
NON_POSITIVE_ARRAY_DIMENSION:
problemMessage: Array dimensions must be positive numbers.
correctionMessage: Try changing the input to a positive number.
comment: No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a dimension given in an `Array`
annotation is less than or equal to zero (`0`).
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because an array dimension of
`-1` was provided:
```dart
import 'dart:ffi';
final class MyStruct extends Struct {
@Array([!-8!])
external Array<Uint8> a0;
}
```
#### Common fixes
Change the dimension to be a positive integer:
```dart
import 'dart:ffi';
final class MyStruct extends Struct {
@Array(8)
external Array<Uint8> a0;
}
```
NON_SIZED_TYPE_ARGUMENT:
problemMessage: "The type '{1}' isn't a valid type argument for '{0}'. The type argument must be a native integer, 'Float', 'Double', 'Pointer', or subtype of 'Struct', 'Union', or 'AbiSpecificInteger'."
correctionMessage: "Try using a native integer, 'Float', 'Double', 'Pointer', or subtype of 'Struct', 'Union', or 'AbiSpecificInteger'."
comment: |-
Parameters:
0: the name of the field
1: the type of the field
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when the type argument for the class
`Array` isn't one of the valid types: either a native integer, `Float`,
`Double`, `Pointer`, or subtype of `Struct`, `Union`, or
`AbiSpecificInteger`.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the type argument to
`Array` is `Void`, and `Void` isn't one of the valid types:
```dart
import 'dart:ffi';
final class C extends Struct {
@Array(8)
external Array<[!Void!]> a0;
}
```
#### Common fixes
Change the type argument to one of the valid types:
```dart
import 'dart:ffi';
final class C extends Struct {
@Array(8)
external Array<Uint8> a0;
}
```
PACKED_ANNOTATION:
problemMessage: "Structs must have at most one 'Packed' annotation."
correctionMessage: "Try removing extra 'Packed' annotations."
comment: No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a subclass of `Struct` has more
than one `Packed` annotation.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the class `C`, which
is a subclass of `Struct`, has two `Packed` annotations:
```dart
import 'dart:ffi';
@Packed(1)
[!@Packed(1)!]
final class C extends Struct {
external Pointer<Uint8> notEmpty;
}
```
#### Common fixes
Remove all but one of the annotations:
```dart
import 'dart:ffi';
@Packed(1)
final class C extends Struct {
external Pointer<Uint8> notEmpty;
}
```
PACKED_ANNOTATION_ALIGNMENT:
problemMessage: Only packing to 1, 2, 4, 8, and 16 bytes is supported.
correctionMessage: "Try changing the 'Packed' annotation alignment to 1, 2, 4, 8, or 16."
comment: No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when the argument to the `Packed`
annotation isn't one of the allowed values: 1, 2, 4, 8, or 16.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the argument to the
`Packed` annotation (`3`) isn't one of the allowed values:
```dart
import 'dart:ffi';
@Packed([!3!])
final class C extends Struct {
external Pointer<Uint8> notEmpty;
}
```
#### Common fixes
Change the alignment to be one of the allowed values:
```dart
import 'dart:ffi';
@Packed(4)
final class C extends Struct {
external Pointer<Uint8> notEmpty;
}
```
SIZE_ANNOTATION_DIMENSIONS:
problemMessage: "'Array's must have an 'Array' annotation that matches the dimensions."
correctionMessage: "Try adjusting the arguments in the 'Array' annotation."
comment: No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when the number of dimensions
specified in an `Array` annotation doesn't match the number of nested
arrays specified by the type of a field.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the field `a0` has a
type with three nested arrays, but only two dimensions are given in the
`Array` annotation:
```dart
import 'dart:ffi';
final class C extends Struct {
[!@Array(8, 8)!]
external Array<Array<Array<Uint8>>> a0;
}
```
#### Common fixes
If the type of the field is correct, then fix the annotation to have the
required number of dimensions:
```dart
import 'dart:ffi';
final class C extends Struct {
@Array(8, 8, 4)
external Array<Array<Array<Uint8>>> a0;
}
```
If the type of the field is wrong, then fix the type of the field:
```dart
import 'dart:ffi';
final class C extends Struct {
@Array(8, 8)
external Array<Array<Uint8>> a0;
}
```
SUBTYPE_OF_FFI_CLASS_IN_EXTENDS:
removedIn: "3.0"
sharedName: SUBTYPE_OF_FFI_CLASS
problemMessage: "The class '{0}' can't extend '{1}'."
correctionMessage: "Try extending 'Struct' or 'Union'."
comment: |-
Parameters:
0: the name of the subclass
1: the name of the class being extended, implemented, or mixed in
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a class extends any FFI class
other than `Struct` or `Union`, or implements or mixes in any FFI class.
`Struct` and `Union` are the only FFI classes that can be subtyped, and
then only by extending them.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the class `C` extends
`Double`:
```dart
import 'dart:ffi';
final class C extends [!Double!] {}
```
#### Common fixes
If the class should extend either `Struct` or `Union`, then change the
declaration of the class:
```dart
import 'dart:ffi';
final class C extends Struct {
@Int32()
external int i;
}
```
If the class shouldn't extend either `Struct` or `Union`, then remove any
references to FFI classes:
```dart
final class C {}
```
SUBTYPE_OF_FFI_CLASS_IN_IMPLEMENTS:
removedIn: "3.0"
sharedName: SUBTYPE_OF_FFI_CLASS
problemMessage: "The class '{0}' can't implement '{1}'."
correctionMessage: "Try implementing 'Allocator' or 'Finalizable'."
comment: |-
Parameters:
0: the name of the subclass
1: the name of the class being extended, implemented, or mixed in
hasPublishedDocs: true
SUBTYPE_OF_FFI_CLASS_IN_WITH:
removedIn: "3.0"
sharedName: SUBTYPE_OF_FFI_CLASS
problemMessage: "The class '{0}' can't mix in '{1}'."
correctionMessage: "Try extending 'Struct' or 'Union'."
comment: |-
Parameters:
0: the name of the subclass
1: the name of the class being extended, implemented, or mixed in
hasPublishedDocs: true
SUBTYPE_OF_STRUCT_CLASS_IN_EXTENDS:
sharedName: SUBTYPE_OF_STRUCT_CLASS
problemMessage: "The class '{0}' can't extend '{1}' because '{1}' is a subtype of 'Struct', 'Union', or 'AbiSpecificInteger'."
correctionMessage: "Try extending 'Struct', 'Union', or 'AbiSpecificInteger' directly."
comment: |-
Parameters:
0: the name of the subclass
1: the name of the class being extended, implemented, or mixed in
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a class extends, implements, or
mixes in a class that extends either `Struct` or `Union`. Classes can only
extend either `Struct` or `Union` directly.
For more information about FFI, see [C interop using dart:ffi][ffi].
#### Example
The following code produces this diagnostic because the class `C` extends
`S`, and `S` extends `Struct`:
```dart
import 'dart:ffi';
final class S extends Struct {
external Pointer f;
}
final class C extends [!S!] {
external Pointer g;
}
```
#### Common fixes
If you're trying to define a struct or union that shares some fields
declared by a different struct or union, then extend `Struct` or `Union`
directly and copy the shared fields:
```dart
import 'dart:ffi';
final class S extends Struct {
external Pointer f;
}
final class C extends Struct {
external Pointer f;
external Pointer g;
}
```
SUBTYPE_OF_STRUCT_CLASS_IN_IMPLEMENTS:
sharedName: SUBTYPE_OF_STRUCT_CLASS
problemMessage: "The class '{0}' can't implement '{1}' because '{1}' is a subtype of 'Struct', 'Union', or 'AbiSpecificInteger'."
correctionMessage: "Try extending 'Struct', 'Union', or 'AbiSpecificInteger' directly."
comment: |-
Parameters:
0: the name of the subclass
1: the name of the class being extended, implemented, or mixed in
hasPublishedDocs: true
SUBTYPE_OF_STRUCT_CLASS_IN_WITH:
sharedName: SUBTYPE_OF_STRUCT_CLASS
problemMessage: "The class '{0}' can't mix in '{1}' because '{1}' is a subtype of 'Struct', 'Union', or 'AbiSpecificInteger'."
correctionMessage: "Try extending 'Struct', 'Union', or 'AbiSpecificInteger' directly."
comment: |-
Parameters:
0: the name of the subclass
1: the name of the class being extended, implemented, or mixed in
hasPublishedDocs: true
HintCode:
CAN_BE_NULL_AFTER_NULL_AWARE:
problemMessage: "The receiver uses '?.', so its value can be null."
correctionMessage: "Replace the '.' with a '?.' in the invocation."
comment: |-
When the target expression uses '?.' operator, it can be `null`, so all the
subsequent invocations should also use '?.' operator.
Note: This diagnostic is only generated in pre-null safe code.
Note: Since this diagnostic is only produced in pre-null safe code, we do
not plan to go through the exercise of converting it to a Warning.
DEPRECATED_COLON_FOR_DEFAULT_VALUE:
problemMessage: Using a colon as a separator before a default value is deprecated and will not be supported in language version 3.0 and later.
correctionMessage: Try replacing the colon with an equal sign.
hasPublishedDocs: true
comment: |-
No parameters.
Note: Since this diagnostic is only produced in pre-3.0 code, we do not
plan to go through the exercise of converting it to a Warning.
documentation: |-
#### Description
The analyzer produces this diagnostic when a colon is used as the
separator before the default value of an optional parameter. While this
syntax is allowed, it's being deprecated in favor of using an equal sign.
#### Example
The following code produces this diagnostic because a colon is being used
before the default value of the optional parameter `i`:
```dart
void f({int i [!:!] 0}) {}
```
#### Common fixes
Replace the colon with an equal sign.
```dart
void f({int i = 0}) {}
```
DEPRECATED_EXPORT_USE:
problemMessage: "The ability to import '{0}' indirectly is deprecated."
correctionMessage: "Try importing '{0}' directly."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the element
documentation: |-
#### Description
The analyzer produces this diagnostic when one library imports a name from
a second library, and the second library exports the name from a third
library but has indicated that it won't export the third library in the
future.
#### Example
Given a library `a.dart` defining the class `A`:
```dart
%uri="lib/a.dart"
class A {}
```
And a second library `b.dart` that exports `a.dart` but has marked the
export as being deprecated:
```dart
%uri="lib/b.dart"
import 'a.dart';
@deprecated
export 'a.dart';
```
The following code produces this diagnostic because the class `A` won't be
exported from `b.dart` in some future version:
```dart
import 'b.dart';
[!A!]? a;
```
#### Common fixes
If the name is available from a different library that you can import,
then replace the existing import with an import for that library (or add
an import for the defining library if you still need the old import):
```dart
import 'a.dart';
A? a;
```
If the name isn't available, then look for instructions from the library
author or contact them directly to find out how to update your code.
DEPRECATED_MEMBER_USE:
problemMessage: "'{0}' is deprecated and shouldn't be used."
correctionMessage: Try replacing the use of the deprecated member with the replacement.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the member
documentation: |-
#### Description
The analyzer produces this diagnostic when a deprecated library or class
member is used in a different package.
#### Example
If the method `m` in the class `C` is annotated with `@deprecated`, then
the following code produces this diagnostic:
```dart
void f(C c) {
c.[!m!]();
}
```
#### Common fixes
The documentation for declarations that are annotated with `@deprecated`
should indicate what code to use in place of the deprecated code.
DEPRECATED_MEMBER_USE_WITH_MESSAGE:
sharedName: DEPRECATED_MEMBER_USE
problemMessage: "'{0}' is deprecated and shouldn't be used. {1}"
correctionMessage: Try replacing the use of the deprecated member with the replacement.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the member
1: message details
DEPRECATED_MEMBER_USE_FROM_SAME_PACKAGE:
problemMessage: "'{0}' is deprecated and shouldn't be used."
correctionMessage: Try replacing the use of the deprecated member with the replacement.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the member
This code is deprecated in favor of the
'deprecated_member_from_same_package' lint rule, and will be removed.
documentation: |-
#### Description
The analyzer produces this diagnostic when a deprecated library member or
class member is used in the same package in which it's declared.
#### Example
The following code produces this diagnostic because `x` is deprecated:
```dart
@deprecated
var x = 0;
var y = [!x!];
```
#### Common fixes
The fix depends on what's been deprecated and what the replacement is. The
documentation for deprecated declarations should indicate what code to use
in place of the deprecated code.
DEPRECATED_MEMBER_USE_FROM_SAME_PACKAGE_WITH_MESSAGE:
sharedName: DEPRECATED_MEMBER_USE_FROM_SAME_PACKAGE
problemMessage: "'{0}' is deprecated and shouldn't be used. {1}"
correctionMessage: Try replacing the use of the deprecated member with the replacement.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the member
1: message details
This code is deprecated in favor of the
'deprecated_member_from_same_package' lint rule, and will be removed.
DIVISION_OPTIMIZATION:
problemMessage: The operator x ~/ y is more efficient than (x / y).toInt().
correctionMessage: "Try re-writing the expression to use the '~/' operator."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the result of dividing two
numbers is converted to an integer using `toInt`. Dart has a built-in
integer division operator that is both more efficient and more concise.
#### Example
The following code produces this diagnostic because the result of dividing
`x` and `y` is converted to an integer using `toInt`:
```dart
int divide(num x, num y) => [!(x / y).toInt()!];
```
#### Common fixes
Use the integer division operator (`~/`):
```dart
int divide(num x, num y) => x ~/ y;
```
IMPORT_DEFERRED_LIBRARY_WITH_LOAD_FUNCTION:
problemMessage: "The imported library defines a top-level function named 'loadLibrary' that is hidden by deferring this library."
correctionMessage: Try changing the import to not be deferred, or rename the function in the imported library.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a library that declares a
function named `loadLibrary` is imported using a deferred import. A
deferred import introduces an implicit function named `loadLibrary`. This
function is used to load the contents of the deferred library, and the
implicit function hides the explicit declaration in the deferred library.
For more information, check out
[Lazily loading a library](https://dart.dev/language/libraries#lazily-loading-a-library).
#### Example
Given a file `a.dart` that defines a function named `loadLibrary`:
```dart
%uri="lib/a.dart"
void loadLibrary(Library library) {}
class Library {}
```
The following code produces this diagnostic because the implicit
declaration of `a.loadLibrary` is hiding the explicit declaration of
`loadLibrary` in `a.dart`:
```dart
[!import 'a.dart' deferred as a;!]
void f() {
a.Library();
}
```
#### Common fixes
If the imported library isn't required to be deferred, then remove the
keyword `deferred`:
```dart
import 'a.dart' as a;
void f() {
a.Library();
}
```
If the imported library is required to be deferred and you need to
reference the imported function, then rename the function in the imported
library:
```dart
void populateLibrary(Library library) {}
class Library {}
```
If the imported library is required to be deferred and you don't need to
reference the imported function, then add a `hide` clause:
```dart
import 'a.dart' deferred as a hide loadLibrary;
void f() {
a.Library();
}
```
IMPORT_OF_LEGACY_LIBRARY_INTO_NULL_SAFE:
problemMessage: "The library '{0}' is legacy, and shouldn't be imported into a null safe library."
correctionMessage: Try migrating the imported library.
comment: |-
https://github.com/dart-lang/sdk/issues/44063
Parameters:
0: the name of the library
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a library that is null safe
imports a library that isn't null safe.
#### Example
Given a file `a.dart` that contains the following:
```dart
%uri="lib/a.dart"
// @dart = 2.9
class A {}
```
The following code produces this diagnostic because a library that null
safe is importing a library that isn't null safe:
```dart
import [!'a.dart'!];
A? f() => null;
```
#### Common fixes
If you can migrate the imported library to be null safe, then migrate it
and update or remove the migrated library's language version.
If you can't migrate the imported library, then the importing library
needs to have a language version that is before 2.12, when null safety was
enabled by default.
UNIGNORABLE_IGNORE:
problemMessage: "The diagnostic '{0}' can't be ignored."
correctionMessage: Try removing the name from the list, or removing the whole comment if this is the only name in the list.
comment: |-
Parameters:
0: the name of the non-diagnostic being ignored
UNNECESSARY_CAST:
problemMessage: Unnecessary cast.
correctionMessage: Try removing the cast.
deprecatedMessage: Use 'WarningCode.UNNECESSARY_CAST' instead.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the value being cast is already
known to be of the type that it's being cast to.
#### Example
The following code produces this diagnostic because `n` is already known to
be an `int` as a result of the `is` test:
```dart
void f(num n) {
if (n is int) {
([!n as int!]).isEven;
}
}
```
#### Common fixes
Remove the unnecessary cast:
```dart
void f(num n) {
if (n is int) {
n.isEven;
}
}
```
UNNECESSARY_IMPORT:
problemMessage: "The import of '{0}' is unnecessary because all of the used elements are also provided by the import of '{1}'."
correctionMessage: Try removing the import directive.
hasPublishedDocs: true
comment: |-
Parameters:
0: the URI that is not necessary
1: the URI that makes it unnecessary
documentation: |-
#### Description
The analyzer produces this diagnostic when an import isn't needed because
all of the names that are imported and referenced within the importing
library are also visible through another import.
#### Example
Given a file `a.dart` that contains the following:
```dart
%uri="lib/a.dart"
class A {}
```
And, given a file `b.dart` that contains the following:
```dart
%uri="lib/b.dart"
export 'a.dart';
class B {}
```
The following code produces this diagnostic because the class `A`, which is
imported from `a.dart`, is also imported from `b.dart`. Removing the import
of `a.dart` leaves the semantics unchanged:
```dart
import [!'a.dart'!];
import 'b.dart';
void f(A a, B b) {}
```
#### Common fixes
If the import isn't needed, then remove it.
If some of the names imported by this import are intended to be used but
aren't yet, and if those names aren't imported by other imports, then add
the missing references to those names.
UNREACHABLE_SWITCH_CASE:
problemMessage: "This case is covered by the previous cases."
correctionMessage: Try removing the case clause, or restructuring the preceding patterns.
deprecatedMessage: Use 'WarningCode.UNREACHABLE_SWITCH_CASE' instead.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a `case` clause in a `switch`
statement doesn't match anything because all of the matchable values are
matched by an earlier `case` clause.
#### Example
The following code produces this diagnostic because the value `1` was
matched in the preceding case:
```dart
void f(int x) {
switch (x) {
case 1:
print('one');
[!case!] 1:
print('two');
}
}
```
#### Common fixes
Change one or both of the conflicting cases to match different values:
```dart
void f(int x) {
switch (x) {
case 1:
print('one');
case 2:
print('two');
}
}
```
UNUSED_ELEMENT:
problemMessage: "The declaration '{0}' isn't referenced."
correctionMessage: "Try removing the declaration of '{0}'."
deprecatedMessage: Use 'WarningCode.UNUSED_ELEMENT' instead.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name that is declared but not referenced
documentation: |-
#### Description
The analyzer produces this diagnostic when a private declaration isn't
referenced in the library that contains the declaration. The following
kinds of declarations are analyzed:
- Private top-level declarations and all of their members
- Private members of public declarations
- Optional parameters of private functions for which a value is never
passed
Not all references to an element will mark it as "used":
- Assigning a value to a top-level variable (with a standard `=`
assignment, or a null-aware `??=` assignment) does not count as using
it.
- Referring to an element in a doc comment reference does not count as
using it.
- Referring to a class, mixin, or enum on the right side of an `is`
expression does not count as using it.
#### Example
Assuming that no code in the library references `_C`, the following code
produces this diagnostic:
```dart
class [!_C!] {}
```
Assuming that no code in the library passes a value for `y` in any
invocation of `_m`, the following code produces this diagnostic:
```dart
%language=2.9
class C {
void _m(int x, [int [!y!]]) {}
void n() => _m(0);
}
```
#### Common fixes
If the declaration isn't needed, then remove it:
```dart
class C {
void _m(int x) {}
void n() => _m(0);
}
```
If the declaration is intended to be used, then add the code to use it.
UNUSED_ELEMENT_PARAMETER:
sharedName: UNUSED_ELEMENT
problemMessage: "A value for optional parameter '{0}' isn't ever given."
correctionMessage: Try removing the unused parameter.
deprecatedMessage: Use 'WarningCode.UNUSED_ELEMENT_PARAMETER' instead.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the parameter that is declared but not used
UNUSED_LOCAL_VARIABLE:
aliasFor: WarningCode.UNUSED_LOCAL_VARIABLE
comment: This is the deprecated alias for [WarningCode.UNUSED_LOCAL_VARIABLE].
LanguageCode:
IMPLICIT_DYNAMIC_FIELD:
problemMessage: "Missing field type for '{0}'."
correctionMessage: Try adding an explicit type, or remove implicit-dynamic from your analysis options file.
comment: |-
Parameters:
0: the name of the field
IMPLICIT_DYNAMIC_FUNCTION:
problemMessage: "Missing type arguments for generic function '{0}<{1}>'."
correctionMessage: Try adding an explicit type, or remove implicit-dynamic from your analysis options file.
comment: |-
Parameters:
0: the name of the function
1: the names of the type arguments
IMPLICIT_DYNAMIC_INVOKE:
problemMessage: "Missing type arguments for calling generic function type '{0}'."
correctionMessage: Try adding an explicit type, or remove implicit-dynamic from your analysis options file.
comment: |-
Parameters:
0: the name of type
IMPLICIT_DYNAMIC_LIST_LITERAL:
problemMessage: Missing type argument for list literal.
correctionMessage: Try adding an explicit type, or remove implicit-dynamic from your analysis options file.
IMPLICIT_DYNAMIC_MAP_LITERAL:
problemMessage: Missing type arguments for map literal.
correctionMessage: Try adding an explicit type, or remove implicit-dynamic from your analysis options file.
IMPLICIT_DYNAMIC_METHOD:
problemMessage: "Missing type arguments for generic method '{0}<{1}>'."
correctionMessage: Try adding an explicit type, or remove implicit-dynamic from your analysis options file.
comment: |-
Parameters:
0: the name of the function
1: the names of the type arguments
IMPLICIT_DYNAMIC_PARAMETER:
problemMessage: "Missing parameter type for '{0}'."
correctionMessage: Try adding an explicit type, or remove implicit-dynamic from your analysis options file.
comment: |-
Parameters:
0: the name of the parameter
IMPLICIT_DYNAMIC_RETURN:
problemMessage: "Missing return type for '{0}'."
correctionMessage: Try adding an explicit type, or remove implicit-dynamic from your analysis options file.
comment: |-
Parameters:
0: the name of the function or method
IMPLICIT_DYNAMIC_TYPE:
problemMessage: "Missing type arguments for generic type '{0}'."
correctionMessage: Try adding an explicit type, or remove implicit-dynamic from your analysis options file.
comment: |-
Parameters:
0: the name of the type
IMPLICIT_DYNAMIC_VARIABLE:
problemMessage: "Missing variable type for '{0}'."
correctionMessage: Try adding an explicit type, or remove implicit-dynamic from your analysis options file.
comment: |-
Parameters:
0: the name of the variable
ManifestWarningCode:
CAMERA_PERMISSIONS_INCOMPATIBLE:
problemMessage: Camera permissions make app incompatible for Chrome OS, consider adding optional features "android.hardware.camera" and "android.hardware.camera.autofocus".
correctionMessage: "Try adding `<uses-feature android:name=\"android.hardware.camera\" android:required=\"false\">` `<uses-feature android:name=\"android.hardware.camera.autofocus\" android:required=\"false\">`."
comment: |-
A code indicating that the camera permissions is not supported on Chrome
OS.
NON_RESIZABLE_ACTIVITY:
problemMessage: The `<activity>` element should be allowed to be resized to allow users to take advantage of the multi-window environment on Chrome OS
correctionMessage: Consider declaring the corresponding activity element with `resizableActivity="true"` attribute.
comment: A code indicating that the activity is set to be non resizable.
NO_TOUCHSCREEN_FEATURE:
problemMessage: "The default \"android.hardware.touchscreen\" needs to be optional for Chrome OS. "
correctionMessage: "Consider adding <uses-feature android:name=\"android.hardware.touchscreen\" android:required=\"false\" /> to the manifest."
comment: |-
A code indicating that the touchscreen feature is not specified in the
manifest.
PERMISSION_IMPLIES_UNSUPPORTED_HARDWARE:
problemMessage: "Permission makes app incompatible for Chrome OS, consider adding optional {0} feature tag, "
correctionMessage: " Try adding `<uses-feature android:name=\"{0}\" android:required=\"false\">`."
comment: |-
A code indicating that a specified permission is not supported on Chrome
OS.
Parameters:
0: the name of the feature tag
SETTING_ORIENTATION_ON_ACTIVITY:
problemMessage: The `<activity>` element should not be locked to any orientation so that users can take advantage of the multi-window environments and larger screens on Chrome OS
correctionMessage: Consider declaring the corresponding activity element with `screenOrientation="unspecified"` or `"fullSensor"` attribute.
comment: A code indicating that the activity is locked to an orientation.
UNSUPPORTED_CHROME_OS_FEATURE:
problemMessage: "The feature {0} isn't supported on Chrome OS, consider making it optional."
correctionMessage: "Try changing to `android:required=\"false\"` for this feature."
comment: |-
A code indicating that a specified feature is not supported on Chrome OS.
Parameters:
0: the name of the feature
UNSUPPORTED_CHROME_OS_HARDWARE:
problemMessage: "The feature {0} isn't supported on Chrome OS, consider making it optional."
correctionMessage: "Try adding `android:required=\"false\"` for this feature."
comment: |-
A code indicating that a specified hardware feature is not supported on
Chrome OS.
Parameters:
0: the name of the feature
ParserErrorCode:
ABSTRACT_ENUM:
problemMessage: "Enums can't be declared to be 'abstract'."
correctionMessage: "Try removing the keyword 'abstract'."
ABSTRACT_STATIC_METHOD:
problemMessage: "Static methods can't be declared to be 'abstract'."
correctionMessage: "Try removing the keyword 'abstract'."
ABSTRACT_TOP_LEVEL_FUNCTION:
problemMessage: "Top-level functions can't be declared to be 'abstract'."
correctionMessage: "Try removing the keyword 'abstract'."
ABSTRACT_TOP_LEVEL_VARIABLE:
problemMessage: "Top-level variables can't be declared to be 'abstract'."
correctionMessage: "Try removing the keyword 'abstract'."
ABSTRACT_TYPEDEF:
problemMessage: "Typedefs can't be declared to be 'abstract'."
correctionMessage: "Try removing the keyword 'abstract'."
ASYNC_KEYWORD_USED_AS_IDENTIFIER:
problemMessage: "The keywords 'await' and 'yield' can't be used as identifiers in an asynchronous or generator function."
comment: |-
16.32 Identifier Reference: It is a compile-time error if any of the
identifiers async, await, or yield is used as an identifier in a function
body marked with either async, async, or sync.
CONST_CONSTRUCTOR_WITH_BODY:
problemMessage: "Const constructors can't have a body."
correctionMessage: "Try removing either the 'const' keyword or the body."
CONST_ENUM:
problemMessage: "Enums can't be declared to be 'const'."
correctionMessage: "Try removing the 'const' keyword."
CONST_TYPEDEF:
problemMessage: "Type aliases can't be declared to be 'const'."
correctionMessage: "Try removing the 'const' keyword."
COVARIANT_CONSTRUCTOR:
problemMessage: "A constructor can't be declared to be 'covariant'."
correctionMessage: "Try removing the keyword 'covariant'."
COVARIANT_TOP_LEVEL_DECLARATION:
problemMessage: "Top-level declarations can't be declared to be covariant."
correctionMessage: "Try removing the keyword 'covariant'."
DEFAULT_VALUE_IN_FUNCTION_TYPE:
problemMessage: "Parameters in a function type can't have default values."
correctionMessage: Try removing the default value.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a function type associated with
a parameter includes optional parameters that have a default value. This
isn't allowed because the default values of parameters aren't part of the
function's type, and therefore including them doesn't provide any value.
#### Example
The following code produces this diagnostic because the parameter `p` has a
default value even though it's part of the type of the parameter `g`:
```dart
void f(void Function([int p [!=!] 0]) g) {
}
```
#### Common fixes
Remove the default value from the function-type's parameter:
```dart
void f(void Function([int p]) g) {
}
```
EMPTY_ENUM_BODY:
problemMessage: An enum must declare at least one constant name.
correctionMessage: Try declaring a constant.
EXPECTED_CASE_OR_DEFAULT:
problemMessage: "Expected 'case' or 'default'."
correctionMessage: Try placing this code inside a case clause.
EXPECTED_CLASS_MEMBER:
problemMessage: Expected a class member.
correctionMessage: Try placing this code inside a class member.
EXPECTED_EXECUTABLE:
problemMessage: Expected a method, getter, setter or operator declaration.
correctionMessage: This appears to be incomplete code. Try removing it or completing it.
EXPECTED_LIST_OR_MAP_LITERAL:
problemMessage: Expected a list or map literal.
correctionMessage: Try inserting a list or map literal, or remove the type arguments.
EXPECTED_NAMED_TYPE_EXTENDS:
sharedName: EXPECTED_NAMED_TYPE
problemMessage: Expected a class name.
correctionMessage: Try using a class name, possibly with type arguments.
EXPECTED_NAMED_TYPE_IMPLEMENTS:
sharedName: EXPECTED_NAMED_TYPE
problemMessage: Expected the name of a class or mixin.
correctionMessage: Try using a class or mixin name, possibly with type arguments.
EXPECTED_NAMED_TYPE_ON:
sharedName: EXPECTED_NAMED_TYPE
problemMessage: Expected the name of a class or mixin.
correctionMessage: Try using a class or mixin name, possibly with type arguments.
EXPECTED_NAMED_TYPE_WITH:
sharedName: EXPECTED_NAMED_TYPE
problemMessage: Expected a mixin name.
correctionMessage: Try using a mixin name, possibly with type arguments.
EXPECTED_REPRESENTATION_FIELD:
problemMessage: Expected a representation field.
correctionMessage: Try providing the representation field for this extension type.
EXPECTED_REPRESENTATION_TYPE:
problemMessage: Expected a representation type.
correctionMessage: Try providing the representation type for this extension type.
EXPECTED_STRING_LITERAL:
problemMessage: Expected a string literal.
EXPECTED_TOKEN:
problemMessage: "Expected to find '{0}'."
comment: |-
Parameters:
0: the token that was expected but not found
EXPECTED_TYPE_NAME:
problemMessage: Expected a type name.
EXTERNAL_GETTER_WITH_BODY:
problemMessage: "External getters can't have a body."
correctionMessage: "Try removing the body of the getter, or removing the keyword 'external'."
EXTERNAL_OPERATOR_WITH_BODY:
problemMessage: "External operators can't have a body."
correctionMessage: "Try removing the body of the operator, or removing the keyword 'external'."
EXTERNAL_SETTER_WITH_BODY:
problemMessage: "External setters can't have a body."
correctionMessage: "Try removing the body of the setter, or removing the keyword 'external'."
FACTORY_WITHOUT_BODY:
problemMessage: "A non-redirecting 'factory' constructor must have a body."
correctionMessage: Try adding a body to the constructor.
FACTORY_WITH_INITIALIZERS:
problemMessage: "A 'factory' constructor can't have initializers."
correctionMessage: "Try removing the 'factory' keyword to make this a generative constructor, or removing the initializers."
FINAL_CLASS:
problemMessage: "Classes can't be declared to be 'final'."
correctionMessage: "Try removing the keyword 'final'."
FINAL_CONSTRUCTOR:
problemMessage: "A constructor can't be declared to be 'final'."
correctionMessage: "Try removing the keyword 'final'."
FINAL_METHOD:
problemMessage: "Getters, setters and methods can't be declared to be 'final'."
correctionMessage: "Try removing the keyword 'final'."
FINAL_TYPEDEF:
problemMessage: "Typedefs can't be declared to be 'final'."
correctionMessage: "Try removing the keyword 'final'."
GETTER_IN_FUNCTION:
problemMessage: "Getters can't be defined within methods or functions."
correctionMessage: Try moving the getter outside the method or function, or converting the getter to a function.
GETTER_WITH_PARAMETERS:
problemMessage: Getters must be declared without a parameter list.
correctionMessage: "Try removing the parameter list, or removing the keyword 'get' to define a method rather than a getter."
INVALID_CODE_POINT:
problemMessage: "The escape sequence '{0}' isn't a valid code point."
comment: |-
Parameters:
0: the invalid escape sequence
INVALID_COMMENT_REFERENCE:
problemMessage: "Comment references should contain a possibly prefixed identifier and can start with 'new', but shouldn't contain anything else."
INVALID_GENERIC_FUNCTION_TYPE:
problemMessage: Invalid generic function type.
correctionMessage: "Try using a generic function type (returnType 'Function(' parameters ')')."
INVALID_LITERAL_IN_CONFIGURATION:
problemMessage: "The literal in a configuration can't contain interpolation."
correctionMessage: Try removing the interpolation expressions.
INVALID_OPERATOR_FOR_SUPER:
problemMessage: "The operator '{0}' can't be used with 'super'."
comment: |-
Parameters:
0: the operator being applied to 'super'
Only generated by the old parser.
Replaced by INVALID_OPERATOR_QUESTIONMARK_PERIOD_FOR_SUPER.
INVALID_STAR_AFTER_ASYNC:
problemMessage: "The modifier 'async*' isn't allowed for an expression function body."
correctionMessage: Try converting the body to a block.
INVALID_SYNC:
problemMessage: "The modifier 'sync' isn't allowed for an expression function body."
correctionMessage: Try converting the body to a block.
LOCAL_FUNCTION_DECLARATION_MODIFIER:
problemMessage: "Local function declarations can't specify any modifiers."
correctionMessage: Try removing the modifier.
MISSING_CLOSING_PARENTHESIS:
problemMessage: The closing parenthesis is missing.
correctionMessage: Try adding the closing parenthesis.
MISSING_ENUM_BODY:
problemMessage: An enum definition must have a body with at least one constant name.
correctionMessage: Try adding a body and defining at least one constant.
MISSING_EXPRESSION_IN_INITIALIZER:
problemMessage: Expected an expression after the assignment operator.
correctionMessage: Try adding the value to be assigned, or remove the assignment operator.
MISSING_FUNCTION_BODY:
problemMessage: A function body must be provided.
correctionMessage: Try adding a function body.
MISSING_FUNCTION_KEYWORD:
problemMessage: "Function types must have the keyword 'Function' before the parameter list."
correctionMessage: "Try adding the keyword 'Function'."
MISSING_FUNCTION_PARAMETERS:
problemMessage: Functions must have an explicit list of parameters.
correctionMessage: Try adding a parameter list.
MISSING_GET:
problemMessage: "Getters must have the keyword 'get' before the getter name."
correctionMessage: "Try adding the keyword 'get'."
MISSING_IDENTIFIER:
problemMessage: Expected an identifier.
MISSING_METHOD_PARAMETERS:
problemMessage: Methods must have an explicit list of parameters.
correctionMessage: Try adding a parameter list.
MISSING_NAME_FOR_NAMED_PARAMETER:
problemMessage: Named parameters in a function type must have a name
correctionMessage: Try providing a name for the parameter or removing the curly braces.
MISSING_NAME_IN_LIBRARY_DIRECTIVE:
problemMessage: Library directives must include a library name.
correctionMessage: "Try adding a library name after the keyword 'library', or remove the library directive if the library doesn't have any parts."
MISSING_NAME_IN_PART_OF_DIRECTIVE:
problemMessage: Part-of directives must include a library name.
correctionMessage: "Try adding a library name after the 'of'."
MISSING_STAR_AFTER_SYNC:
problemMessage: "The modifier 'sync' must be followed by a star ('*')."
correctionMessage: Try removing the modifier, or add a star.
MISSING_TERMINATOR_FOR_PARAMETER_GROUP:
problemMessage: "There is no '{0}' to close the parameter group."
correctionMessage: "Try inserting a '{0}' at the end of the group."
comment: |-
Parameters:
0: the terminator that is missing
MISSING_TYPEDEF_PARAMETERS:
problemMessage: Typedefs must have an explicit list of parameters.
correctionMessage: Try adding a parameter list.
MISSING_VARIABLE_IN_FOR_EACH:
problemMessage: "A loop variable must be declared in a for-each loop before the 'in', but none was found."
correctionMessage: Try declaring a loop variable.
MIXED_PARAMETER_GROUPS:
problemMessage: "Can't have both positional and named parameters in a single parameter list."
correctionMessage: Try choosing a single style of optional parameters.
MULTIPLE_IMPLEMENTS_CLAUSES:
problemMessage: Each class or mixin definition can have at most one implements clause.
correctionMessage: Try combining all of the implements clauses into a single clause.
MULTIPLE_NAMED_PARAMETER_GROUPS:
problemMessage: "Can't have multiple groups of named parameters in a single parameter list."
correctionMessage: Try combining all of the groups into a single group.
MULTIPLE_POSITIONAL_PARAMETER_GROUPS:
problemMessage: "Can't have multiple groups of positional parameters in a single parameter list."
correctionMessage: Try combining all of the groups into a single group.
MULTIPLE_VARIABLES_IN_FOR_EACH:
problemMessage: "A single loop variable must be declared in a for-each loop before the 'in', but {0} were found."
correctionMessage: Try moving all but one of the declarations inside the loop body.
comment: |-
Parameters:
0: the number of variables being declared
NAMED_FUNCTION_EXPRESSION:
problemMessage: "Function expressions can't be named."
correctionMessage: Try removing the name, or moving the function expression to a function declaration statement.
NAMED_FUNCTION_TYPE:
problemMessage: "Function types can't be named."
correctionMessage: "Try replacing the name with the keyword 'Function'."
NAMED_PARAMETER_OUTSIDE_GROUP:
problemMessage: "Named parameters must be enclosed in curly braces ('{' and '}')."
correctionMessage: Try surrounding the named parameters in curly braces.
NATIVE_CLAUSE_IN_NON_SDK_CODE:
problemMessage: Native clause can only be used in the SDK and code that is loaded through native extensions.
correctionMessage: Try removing the native clause.
NATIVE_FUNCTION_BODY_IN_NON_SDK_CODE:
problemMessage: Native functions can only be declared in the SDK and code that is loaded through native extensions.
correctionMessage: "Try removing the word 'native'."
NON_CONSTRUCTOR_FACTORY:
problemMessage: Only a constructor can be declared to be a factory.
correctionMessage: "Try removing the keyword 'factory'."
NON_IDENTIFIER_LIBRARY_NAME:
problemMessage: The name of a library must be an identifier.
correctionMessage: Try using an identifier as the name of the library.
NON_PART_OF_DIRECTIVE_IN_PART:
problemMessage: The part-of directive must be the only directive in a part.
correctionMessage: Try removing the other directives, or moving them to the library for which this is a part.
NON_STRING_LITERAL_AS_URI:
problemMessage: The URI must be a string literal.
correctionMessage: Try enclosing the URI in either single or double quotes.
NON_USER_DEFINABLE_OPERATOR:
problemMessage: "The operator '{0}' isn't user definable."
comment: |-
Parameters:
0: the operator that the user is trying to define
NORMAL_BEFORE_OPTIONAL_PARAMETERS:
problemMessage: Normal parameters must occur before optional parameters.
correctionMessage: Try moving all of the normal parameters before the optional parameters.
POSITIONAL_AFTER_NAMED_ARGUMENT:
problemMessage: Positional arguments must occur before named arguments.
correctionMessage: Try moving all of the positional arguments before the named arguments.
POSITIONAL_PARAMETER_OUTSIDE_GROUP:
problemMessage: "Positional parameters must be enclosed in square brackets ('[' and ']')."
correctionMessage: Try surrounding the positional parameters in square brackets.
SETTER_IN_FUNCTION:
problemMessage: "Setters can't be defined within methods or functions."
correctionMessage: Try moving the setter outside the method or function.
STATIC_GETTER_WITHOUT_BODY:
problemMessage: "A 'static' getter must have a body."
correctionMessage: "Try adding a body to the getter, or removing the keyword 'static'."
STATIC_SETTER_WITHOUT_BODY:
problemMessage: "A 'static' setter must have a body."
correctionMessage: "Try adding a body to the setter, or removing the keyword 'static'."
STATIC_TOP_LEVEL_DECLARATION:
problemMessage: "Top-level declarations can't be declared to be static."
correctionMessage: "Try removing the keyword 'static'."
UNEXPECTED_TERMINATOR_FOR_PARAMETER_GROUP:
problemMessage: "There is no '{0}' to open a parameter group."
correctionMessage: "Try inserting the '{0}' at the appropriate location."
comment: |-
Parameters:
0: the starting character that was missing
UNEXPECTED_TOKEN:
problemMessage: "Unexpected text '{0}'."
correctionMessage: Try removing the text.
comment: |-
Parameters:
0: the unexpected text that was found
VAR_CLASS:
problemMessage: "Classes can't be declared to be 'var'."
correctionMessage: "Try removing the keyword 'var'."
VAR_ENUM:
problemMessage: "Enums can't be declared to be 'var'."
correctionMessage: "Try removing the keyword 'var'."
VAR_TYPEDEF:
problemMessage: "Typedefs can't be declared to be 'var'."
correctionMessage: "Try removing the keyword 'var', or replacing it with the name of the return type."
WRONG_SEPARATOR_FOR_POSITIONAL_PARAMETER:
problemMessage: "The default value of a positional parameter should be preceded by '='."
correctionMessage: "Try replacing the ':' with '='."
WRONG_TERMINATOR_FOR_PARAMETER_GROUP:
problemMessage: "Expected '{0}' to close parameter group."
correctionMessage: "Try replacing '{0}' with '{1}'."
comment: |-
Parameters:
0: the terminator that was expected
1: the terminator that was found
PubspecWarningCode:
ASSET_DIRECTORY_DOES_NOT_EXIST:
problemMessage: "The asset directory '{0}' doesn't exist."
correctionMessage: Try creating the directory or fixing the path to the directory.
hasPublishedDocs: true
comment: |-
Parameters:
0: the path to the asset directory as given in the file.
documentation: |-
#### Description
The analyzer produces this diagnostic when an asset list contains a value
referencing a directory that doesn't exist.
#### Example
Assuming that the directory `assets` doesn't exist, the following code
produces this diagnostic because it's listed as a directory containing
assets:
```yaml
%uri="pubspec.yaml"
name: example
flutter:
assets:
- assets/
```
#### Common fixes
If the path is correct, then create a directory at that path.
If the path isn't correct, then change the path to match the path of the
directory containing the assets.
ASSET_DOES_NOT_EXIST:
problemMessage: "The asset file '{0}' doesn't exist."
correctionMessage: Try creating the file or fixing the path to the file.
hasPublishedDocs: true
comment: |-
Parameters:
0: the path to the asset as given in the file.
documentation: |-
#### Description
The analyzer produces this diagnostic when an asset list contains a value
referencing a file that doesn't exist.
#### Example
Assuming that the file `doesNotExist.gif` doesn't exist, the following code
produces this diagnostic because it's listed as an asset:
```yaml
%uri="pubspec.yaml"
name: example
flutter:
assets:
- doesNotExist.gif
```
#### Common fixes
If the path is correct, then create a file at that path.
If the path isn't correct, then change the path to match the path of the
file containing the asset.
ASSET_FIELD_NOT_LIST:
problemMessage: "The value of the 'asset' field is expected to be a list of relative file paths."
correctionMessage: Try converting the value to be a list of relative file paths.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the value of the `asset` key
isn't a list.
#### Example
The following code produces this diagnostic because the value of the assets
key is a string when a list is expected:
```yaml
%uri="pubspec.yaml"
name: example
flutter:
assets: assets/
```
#### Common fixes
Change the value of the asset list so that it's a list:
```yaml
%uri="pubspec.yaml"
name: example
flutter:
assets:
- assets/
```
ASSET_NOT_STRING:
problemMessage: Assets are required to be file paths (strings).
correctionMessage: Try converting the value to be a string.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when an asset list contains a value
that isn't a string.
#### Example
The following code produces this diagnostic because the asset list contains
a map:
```yaml
%uri="pubspec.yaml"
name: example
flutter:
assets:
- image.gif: true
```
#### Common fixes
Change the asset list so that it only contains valid POSIX-style file
paths:
```yaml
%uri="pubspec.yaml"
name: example
flutter:
assets:
- image.gif
```
DEPENDENCIES_FIELD_NOT_MAP:
problemMessage: "The value of the '{0}' field is expected to be a map."
correctionMessage: Try converting the value to be a map.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the field
documentation: |-
#### Description
The analyzer produces this diagnostic when the value of either the
`dependencies` or `dev_dependencies` key isn't a map.
#### Example
The following code produces this diagnostic because the value of the
top-level `dependencies` key is a list:
```yaml
%uri="pubspec.yaml"
name: example
dependencies:
- meta
```
#### Common fixes
Use a map as the value of the `dependencies` key:
```yaml
%uri="pubspec.yaml"
name: example
dependencies:
meta: ^1.0.2
```
DEPRECATED_FIELD:
problemMessage: "The '{0}' field is no longer used and can be removed."
correctionMessage: Try removing the field.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the field
documentation: |-
#### Description
The analyzer produces this diagnostic when a key is used in a
`pubspec.yaml` file that was deprecated. Unused keys take up space and
might imply semantics that are no longer valid.
#### Example
The following code produces this diagnostic because the `author` key is no
longer being used:
```dart
%uri="pubspec.yaml"
name: example
author: 'Dash'
```
#### Common fixes
Remove the deprecated key:
```dart
%uri="pubspec.yaml"
name: example
```
FLUTTER_FIELD_NOT_MAP:
problemMessage: "The value of the 'flutter' field is expected to be a map."
correctionMessage: Try converting the value to be a map.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the value of the `flutter` key
isn't a map.
#### Example
The following code produces this diagnostic because the value of the
top-level `flutter` key is a string:
```yaml
%uri="pubspec.yaml"
name: example
flutter: true
```
#### Common fixes
If you need to specify Flutter-specific options, then change the value to
be a map:
```yaml
%uri="pubspec.yaml"
name: example
flutter:
uses-material-design: true
```
If you don't need to specify Flutter-specific options, then remove the
`flutter` key:
```yaml
%uri="pubspec.yaml"
name: example
```
INVALID_DEPENDENCY:
problemMessage: "Publishable packages can't have '{0}' dependencies."
correctionMessage: "Try adding a 'publish_to: none' entry to mark the package as not for publishing or remove the {0} dependency."
hasPublishedDocs: true
comment: |-
Parameters:
0: the kind of dependency.
documentation: |-
#### Description
The analyzer produces this diagnostic when a package under either
`dependencies` or `dev_dependencies` isn't a pub, `git`, or `path` based
dependency.
See [Package dependencies](https://dart.dev/tools/pub/dependencies) for
more information about the kind of dependencies that are supported.
#### Example
The following code produces this diagnostic because the dependency on the
package `transmogrify` isn't a pub, `git`, or `path` based dependency:
```yaml
%uri="pubspec.yaml"
name: example
dependencies:
transmogrify:
hosted:
name: transmogrify
url: http://your-package-server.com
version: ^1.4.0
```
#### Common fixes
If you want to publish your package to `pub.dev`, then change the
dependencies to ones that are supported by `pub`.
If you don't want to publish your package to `pub.dev`, then add a
`publish_to: none` entry to mark the package as one that isn't intended to
be published:
```yaml
%uri="pubspec.yaml"
name: example
publish_to: none
dependencies:
transmogrify:
hosted:
name: transmogrify
url: http://your-package-server.com
version: ^1.4.0
```
INVALID_PLATFORMS_FIELD:
problemMessage: "The 'platforms' field must be a map with platforms as keys."
correctionMessage: "Try changing the 'platforms' field to a map with platforms as keys."
hasPublishedDocs: false
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a top-level `platforms`
field is specified, but its value is not a map with keys.
See the [documentation on platform declaration](https://dart.dev/tools/pub/pubspec#platforms)
for details.
#### Example
The following `pubspec.yaml` produces this diagnostic because `platforms`
should be a map.
```yaml
%uri="pubspec.yaml"
name: example
platforms:
[!- android
- web
- ios!]
```
#### Common fixes
If you can rely on automatic platform detection, then omit the
top-level `platforms` field.
```yaml
%uri="pubspec.yaml"
name: example
```
If you need to manually specify the list of supported platforms, then
write the `platforms` field as a map with platform names as keys.
```yaml
%uri="pubspec.yaml"
name: example
platforms:
android:
web:
ios:
```
UNKNOWN_PLATFORM:
problemMessage: "The platform '{0}' is not a recognized platform."
correctionMessage: "Try correcting the platform name or removing it."
hasPublishedDocs: false
comment: |-
Parameters:
0: the unknown platform.
documentation: |-
#### Description
The analyzer produces this diagnostic when an unknown platform name is
used as a key in the `platforms` map.
See the [documentation on platform declaration](https://dart.dev/tools/pub/pubspec#platforms)
for details.
#### Example
The following `pubspec.yaml` produces this diagnostic because the platform
`browser` is unknown.
```yaml
%uri="pubspec.yaml"
name: example
platforms:
[!browser:!]
```
#### Common fixes
If you can rely on automatic platform detection, then omit the
top-level `platforms` key.
```yaml
%uri="pubspec.yaml"
name: example
```
If you need to manually specify the list of supported platforms, then
write the `platforms` field as a map with known platform names as keys.
```yaml
%uri="pubspec.yaml"
name: example
platforms:
# These are the known platforms
android:
ios:
linux:
macos:
web:
windows:
```
PLATFORM_VALUE_DISALLOWED:
problemMessage: "Keys in the `platforms` field can't have values."
correctionMessage: "Try removing the value, while keeping the key."
hasPublishedDocs: false
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a key in the `platforms` map
has a value.
See the [documentation on platform declaration](https://dart.dev/tools/pub/pubspec#platforms)
for details.
#### Example
The following `pubspec.yaml` produces this diagnostic because the key
`web` has a value.
```yaml
%uri="pubspec.yaml"
name: example
platforms:
web: [!"chrome"!]
```
#### Common fixes
Omit the value and leave the key without a value:
```yaml
%uri="pubspec.yaml"
name: example
platforms:
web:
```
Values for keys in the `platforms` field are currently reserved for
potential future behavior.
MISSING_NAME:
problemMessage: "The 'name' field is required but missing."
correctionMessage: "Try adding a field named 'name'."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when there's no top-level `name` key.
The `name` key provides the name of the package, which is required.
#### Example
The following code produces this diagnostic because the package doesn't
have a name:
```yaml
%uri="pubspec.yaml"
dependencies:
meta: ^1.0.2
```
#### Common fixes
Add the top-level key `name` with a value that's the name of the package:
```yaml
%uri="pubspec.yaml"
name: example
dependencies:
meta: ^1.0.2
```
NAME_NOT_STRING:
problemMessage: "The value of the 'name' field is required to be a string."
correctionMessage: Try converting the value to be a string.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the top-level `name` key has a
value that isn't a string.
#### Example
The following code produces this diagnostic because the value following the
`name` key is a list:
```yaml
%uri="pubspec.yaml"
name:
- example
```
#### Common fixes
Replace the value with a string:
```yaml
%uri="pubspec.yaml"
name: example
```
PATH_DOES_NOT_EXIST:
problemMessage: "The path '{0}' doesn't exist."
correctionMessage: Try creating the referenced path or using a path that exists.
hasPublishedDocs: true
comment: |-
Parameters:
0: the path to the dependency as given in the file.
documentation: |-
#### Description
The analyzer produces this diagnostic when a dependency has a `path` key
referencing a directory that doesn't exist.
#### Example
Assuming that the directory `doesNotExist` doesn't exist, the following
code produces this diagnostic because it's listed as the path of a package:
```yaml
%uri="pubspec.yaml"
name: example
dependencies:
local_package:
path: doesNotExist
```
#### Common fixes
If the path is correct, then create a directory at that path.
If the path isn't correct, then change the path to match the path to the
root of the package.
PATH_NOT_POSIX:
problemMessage: "The path '{0}' isn't a POSIX-style path."
correctionMessage: Try converting the value to a POSIX-style path.
hasPublishedDocs: true
comment: |-
Parameters:
0: the path as given in the file.
documentation: |-
#### Description
The analyzer produces this diagnostic when a dependency has a `path` key
whose value is a string, but isn't a POSIX-style path.
#### Example
The following code produces this diagnostic because the path following the
`path` key is a Windows path:
```yaml
%uri="pubspec.yaml"
name: example
dependencies:
local_package:
path: E:\local_package
```
#### Common fixes
Convert the path to a POSIX path.
PATH_PUBSPEC_DOES_NOT_EXIST:
problemMessage: "The directory '{0}' doesn't contain a pubspec."
correctionMessage: Try creating a pubspec in the referenced directory or using a path that has a pubspec.
hasPublishedDocs: true
comment: |-
Parameters:
0: the path to the dependency as given in the file.
documentation: |-
#### Description
The analyzer produces this diagnostic when a dependency has a `path` key
that references a directory that doesn't contain a `pubspec.yaml` file.
#### Example
Assuming that the directory `local_package` doesn't contain a file
`pubspec.yaml`, the following code produces this diagnostic because it's
listed as the path of a package:
```yaml
%uri="pubspec.yaml"
name: example
dependencies:
local_package:
path: local_package
```
#### Common fixes
If the path is intended to be the root of a package, then add a
`pubspec.yaml` file in the directory:
```yaml
%uri="pubspec.yaml"
name: local_package
```
If the path is wrong, then replace it with the correct path.
UNNECESSARY_DEV_DEPENDENCY:
problemMessage: "The dev dependency on {0} is unnecessary because there is also a normal dependency on that package."
correctionMessage: Try removing the dev dependency.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the package in the dev_dependency list.
documentation: |-
#### Description
The analyzer produces this diagnostic when there's an entry under
`dev_dependencies` for a package that is also listed under `dependencies`.
The packages under `dependencies` are available to all of the code in the
package, so there's no need to also list them under `dev_dependencies`.
#### Example
The following code produces this diagnostic because the package `meta` is
listed under both `dependencies` and `dev_dependencies`:
```yaml
%uri="pubspec.yaml"
name: example
dependencies:
meta: ^1.0.2
dev_dependencies:
meta: ^1.0.2
```
#### Common fixes
Remove the entry under `dev_dependencies` (and the `dev_dependencies` key
if that's the only package listed there):
```yaml
%uri="pubspec.yaml"
name: example
dependencies:
meta: ^1.0.2
```
StaticWarningCode:
DEAD_NULL_AWARE_EXPRESSION:
problemMessage: "The left operand can't be null, so the right operand is never executed."
correctionMessage: Try removing the operator and the right operand.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic in two cases.
The first is when the left operand of an `??` operator can't be `null`.
The right operand is only evaluated if the left operand has the value
`null`, and because the left operand can't be `null`, the right operand is
never evaluated.
The second is when the left-hand side of an assignment using the `??=`
operator can't be `null`. The right-hand side is only evaluated if the
left-hand side has the value `null`, and because the left-hand side can't
be `null`, the right-hand side is never evaluated.
#### Examples
The following code produces this diagnostic because `x` can't be `null`:
```dart
int f(int x) {
return x ?? [!0!];
}
```
The following code produces this diagnostic because `f` can't be `null`:
```dart
class C {
int f = -1;
void m(int x) {
f ??= [!x!];
}
}
```
#### Common fixes
If the diagnostic is reported for an `??` operator, then remove the `??`
operator and the right operand:
```dart
int f(int x) {
return x;
}
```
If the diagnostic is reported for an assignment, and the assignment isn't
needed, then remove the assignment:
```dart
class C {
int f = -1;
void m(int x) {
}
}
```
If the assignment is needed, but should be based on a different condition,
then rewrite the code to use `=` and the different condition:
```dart
class C {
int f = -1;
void m(int x) {
if (f < 0) {
f = x;
}
}
}
```
INVALID_NULL_AWARE_OPERATOR:
problemMessage: "The receiver can't be null, so the null-aware operator '{0}' is unnecessary."
correctionMessage: "Try replacing the operator '{0}' with '{1}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the null-aware operator that is invalid
1: the non-null-aware operator that can replace the invalid operator
documentation: |-
#### Description
The analyzer produces this diagnostic when a null-aware operator (`?.`,
`?..`, `?[`, `?..[`, or `...?`) is used on a receiver that's known to be
non-nullable.
#### Examples
The following code produces this diagnostic because `s` can't be `null`:
```dart
int? getLength(String s) {
return s[!?.!]length;
}
```
The following code produces this diagnostic because `a` can't be `null`:
```dart
var a = [];
var b = [[!...?!]a];
```
The following code produces this diagnostic because `s?.length` can't
return `null`:
```dart
void f(String? s) {
s?.length[!?.!]isEven;
}
```
The reason `s?.length` can't return `null` is because the null-aware
operator following `s` short-circuits the evaluation of both `length` and
`isEven` if `s` is `null`. In other words, if `s` is `null`, then neither
`length` nor `isEven` will be invoked, and if `s` is non-`null`, then
`length` can't return a `null` value. Either way, `isEven` can't be invoked
on a `null` value, so the null-aware operator isn't necessary. See
[Understanding null safety](/null-safety/understanding-null-safety#smarter-null-aware-methods)
for more details.
The following code produces this diagnostic because `s` can't be `null`.
```dart
void f(Object? o) {
var s = o as String;
s[!?.!]length;
}
```
The reason `s` can't be null, despite the fact that `o` can be `null`, is
because of the cast to `String`, which is a non-nullable type. If `o` ever
has the value `null`, the cast will fail and the invocation of `length`
will not happen.
#### Common fixes
Replace the null-aware operator with a non-null-aware equivalent; for
example, change `?.` to `.`:
```dart
int getLength(String s) {
return s.length;
}
```
(Note that the return type was also changed to be non-nullable, which might
not be appropriate in some cases.)
INVALID_NULL_AWARE_OPERATOR_AFTER_SHORT_CIRCUIT:
sharedName: INVALID_NULL_AWARE_OPERATOR
problemMessage: "The receiver can't be null because of short-circuiting, so the null-aware operator '{0}' can't be used."
correctionMessage: "Try replacing the operator '{0}' with '{1}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the null-aware operator that is invalid
1: the non-null-aware operator that can replace the invalid operator
MISSING_ENUM_CONSTANT_IN_SWITCH:
problemMessage: "Missing case clause for '{0}'."
correctionMessage: Try adding a case clause for the missing constant, or adding a default clause.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the constant that is missing
documentation: |-
#### Description
The analyzer produces this diagnostic when a `switch` statement for an enum
doesn't include an option for one of the values in the enum.
Note that `null` is always a possible value for an enum and therefore also
must be handled.
#### Example
The following code produces this diagnostic because the enum constant `e2`
isn't handled:
```dart
%language=2.19
enum E { e1, e2 }
void f(E e) {
[!switch (e)!] {
case E.e1:
break;
}
}
```
#### Common fixes
If there's special handling for the missing values, then add a `case`
clause for each of the missing values:
```dart
enum E { e1, e2 }
void f(E e) {
switch (e) {
case E.e1:
break;
case E.e2:
break;
}
}
```
If the missing values should be handled the same way, then add a `default`
clause:
```dart
enum E { e1, e2 }
void f(E e) {
switch (e) {
case E.e1:
break;
default:
break;
}
}
```
TODO(brianwilkerson) This documentation will need to be updated when NNBD
ships.
UNNECESSARY_NON_NULL_ASSERTION:
problemMessage: "The '!' will have no effect because the receiver can't be null."
correctionMessage: "Try removing the '!' operator."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the operand of the `!` operator
can't be `null`.
#### Example
The following code produces this diagnostic because `x` can't be `null`:
```dart
int f(int x) {
return x[!!!];
}
```
#### Common fixes
Remove the null check operator (`!`):
```dart
int f(int x) {
return x;
}
```
UNNECESSARY_NULL_ASSERT_PATTERN:
problemMessage: The null-assert pattern will have no effect because the matched type isn't nullable.
correctionMessage: Try replacing the null-assert pattern with its nested pattern.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a null-assert pattern is used
to match a value that isn't nullable.
#### Example
The following code produces this diagnostic because the variable `x` isn't
nullable:
```dart
void f(int x) {
if (x case var a[!!!] when a > 0) {}
}
```
#### Common fixes
Remove the null-assert pattern:
```dart
void f(int x) {
if (x case var a when a > 0) {}
}
```
UNNECESSARY_NULL_CHECK_PATTERN:
problemMessage: The null-check pattern will have no effect because the matched type isn't nullable.
correctionMessage: Try replacing the null-check pattern with its nested pattern.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a null-check pattern is used to
match a value that isn't nullable.
#### Example
The following code produces this diagnostic because the value `x` isn't
nullable:
```dart
void f(int x) {
if (x case var a[!?!] when a > 0) {}
}
```
#### Common fixes
Remove the null-check pattern:
```dart
void f(int x) {
if (x case var a when a > 0) {}
}
```
WarningCode:
ARGUMENT_TYPE_NOT_ASSIGNABLE_TO_ERROR_HANDLER:
problemMessage: "The argument type '{0}' can't be assigned to the parameter type '{1} Function(Object)' or '{1} Function(Object, StackTrace)'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the actual argument type
1: the name of the expected function return type
documentation: |-
#### Description
The analyzer produces this diagnostic when an invocation of
`Future.catchError` has an argument that is a function whose parameters
aren't compatible with the arguments that will be passed to the function
when it's invoked. The static type of the first argument to `catchError`
is just `Function`, even though the function that is passed in is expected
to have either a single parameter of type `Object` or two parameters of
type `Object` and `StackTrace`.
#### Examples
The following code produces this diagnostic because the closure being
passed to `catchError` doesn't take any parameters, but the function is
required to take at least one parameter:
```dart
void f(Future<int> f) {
f.catchError([!() => 0!]);
}
```
The following code produces this diagnostic because the closure being
passed to `catchError` takes three parameters, but it can't have more than
two required parameters:
```dart
void f(Future<int> f) {
f.catchError([!(one, two, three) => 0!]);
}
```
The following code produces this diagnostic because even though the closure
being passed to `catchError` takes one parameter, the closure doesn't have
a type that is compatible with `Object`:
```dart
void f(Future<int> f) {
f.catchError([!(String error) => 0!]);
}
```
#### Common fixes
Change the function being passed to `catchError` so that it has either one
or two required parameters, and the parameters have the required types:
```dart
void f(Future<int> f) {
f.catchError((Object error) => 0);
}
```
ASSIGNMENT_OF_DO_NOT_STORE:
problemMessage: "'{0}' is marked 'doNotStore' and shouldn't be assigned to a field or top-level variable."
correctionMessage: Try removing the assignment.
comment: |-
Users should not assign values marked `@doNotStore`.
Parameters:
0: the name of the field or variable
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when the value of a function
(including methods and getters) that is explicitly or implicitly marked by
the [`doNotStore`][meta-doNotStore] annotation is stored in either a field
or top-level variable.
#### Example
The following code produces this diagnostic because the value of the
function `f` is being stored in the top-level variable `x`:
```dart
import 'package:meta/meta.dart';
@doNotStore
int f() => 1;
var x = [!f()!];
```
#### Common fixes
Replace references to the field or variable with invocations of the
function producing the value.
BODY_MIGHT_COMPLETE_NORMALLY_CATCH_ERROR:
problemMessage: "This 'onError' handler must return a value assignable to '{0}', but ends without returning a value."
correctionMessage: Try adding a return statement.
hasPublishedDocs: true
comment: |-
Parameters:
0: the return type as derived by the type of the [Future].
documentation: |-
#### Description
The analyzer produces this diagnostic when the closure passed to the
`onError` parameter of the `Future.catchError` method is required to
return a non-`null` value (because of the `Future`s type argument) but can
implicitly return `null`.
#### Example
The following code produces this diagnostic because the closure passed to
the `catchError` method is required to return an `int` but doesn't end
with an explicit `return`, causing it to implicitly return `null`:
```dart
void g(Future<int> f) {
f.catchError((e, st) [!{!]});
}
```
#### Common fixes
If the closure should sometimes return a non-`null` value, then add an
explicit return to the closure:
```dart
void g(Future<int> f) {
f.catchError((e, st) {
return -1;
});
}
```
If the closure should always return `null`, then change the type argument
of the `Future` to be either `void` or `Null`:
```dart
void g(Future<void> f) {
f.catchError((e, st) {});
}
```
BODY_MIGHT_COMPLETE_NORMALLY_NULLABLE:
problemMessage: "This function has a nullable return type of '{0}', but ends without returning a value."
correctionMessage: "Try adding a return statement, or if no value is ever returned, try changing the return type to 'void'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the declared return type
documentation: |-
#### Description
The analyzer produces this diagnostic when a method or function can
implicitly return `null` by falling off the end. While this is valid Dart
code, it's better for the return of `null` to be explicit.
#### Example
The following code produces this diagnostic because the function `f`
implicitly returns `null`:
```dart
String? [!f!]() {}
```
#### Common fixes
If the return of `null` is intentional, then make it explicit:
```dart
String? f() {
return null;
}
```
If the function should return a non-null value along that path, then add
the missing return statement:
```dart
String? f() {
return '';
}
```
CAST_FROM_NULL_ALWAYS_FAILS:
problemMessage: "This cast always throws an exception because the expression always evaluates to 'null'."
comment: |-
No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when an expression whose type is
`Null` is being cast to a non-nullable type.
#### Example
The following code produces this diagnostic because `n` is known to always
be `null`, but it's being cast to a non-nullable type:
```dart
void f(Null n) {
[!n as int!];
}
```
#### Common fixes
Remove the unnecessary cast:
```dart
void f(Null n) {
n;
}
```
CAST_FROM_NULLABLE_ALWAYS_FAILS:
problemMessage: "This cast will always throw an exception because the nullable local variable '{0}' is not assigned."
correctionMessage: "Try giving it an initializer expression, or ensure that it's assigned on every execution path."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the unassigned variable
documentation: |-
#### Description
The analyzer produces this diagnostic when a local variable that has a
nullable type hasn't been assigned and is cast to a non-nullable type.
Because the variable hasn't been assigned it has the default value of
`null`, causing the cast to throw an exception.
#### Example
The following code produces this diagnostic because the variable `x` is
cast to a non-nullable type (`int`) when it's known to have the value
`null`:
```dart
void f() {
num? x;
[!x!] as int;
print(x);
}
```
#### Common fixes
If the variable is expected to have a value before the cast, then add an
initializer or an assignment:
```dart
void f() {
num? x = 3;
x as int;
print(x);
}
```
If the variable isn't expected to be assigned, then remove the cast:
```dart
void f() {
num? x;
print(x);
}
```
CONSTANT_PATTERN_NEVER_MATCHES_VALUE_TYPE:
problemMessage: "The matched value type '{0}' can never be equal to this constant of type '{1}'."
correctionMessage: "Try a constant of the same type as the matched value type."
hasPublishedDocs: true
comment: |-
Parameters:
0: the matched value type
1: the constant value type
documentation: |-
#### Description
The analyzer produces this diagnostic when a constant pattern can never
match the value it's being tested against because the type of the constant
is known to never match the type of the value.
#### Example
The following code produces this diagnostic because the type of the
constant pattern `(true)` is `bool`, and the type of the value being
matched (`x`) is `int`, and a Boolean can never match an integer:
```dart
void f(int x) {
if (x case [!true!]) {}
}
```
#### Common fixes
If the type of the value is correct, then rewrite the pattern to be
compatible:
```dart
void f(int x) {
if (x case 3) {}
}
```
If the type of the constant is correct, then rewrite the value to be
compatible:
```dart
void f(bool x) {
if (x case true) {}
}
```
DEAD_CODE:
problemMessage: Dead code.
correctionMessage: Try removing the code, or fixing the code before it so that it can be reached.
hasPublishedDocs: true
comment: |-
Dead code is code that is never reached, this can happen for instance if a
statement follows a return statement.
No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when code is found that won't be
executed because execution will never reach the code.
#### Example
The following code produces this diagnostic because the invocation of
`print` occurs after the function has returned:
```dart
void f() {
return;
[!print('here');!]
}
```
#### Common fixes
If the code isn't needed, then remove it:
```dart
void f() {
return;
}
```
If the code needs to be executed, then either move the code to a place
where it will be executed:
```dart
void f() {
print('here');
return;
}
```
Or, rewrite the code before it, so that it can be reached:
```dart
void f({bool skipPrinting = true}) {
if (skipPrinting) {
return;
}
print('here');
}
```
DEAD_CODE_CATCH_FOLLOWING_CATCH:
problemMessage: "Dead code: Catch clauses after a 'catch (e)' or an 'on Object catch (e)' are never reached."
correctionMessage: Try reordering the catch clauses so that they can be reached, or removing the unreachable catch clauses.
hasPublishedDocs: true
comment: |-
Dead code is code that is never reached. This case covers cases where the
user has catch clauses after `catch (e)` or `on Object catch (e)`.
No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a `catch` clause is found that
can't be executed because it's after a `catch` clause of the form
`catch (e)` or `on Object catch (e)`. The first `catch` clause that matches
the thrown object is selected, and both of those forms will match any
object, so no `catch` clauses that follow them will be selected.
#### Example
The following code produces this diagnostic:
```dart
void f() {
try {
} catch (e) {
} [!on String {
}!]
}
```
#### Common fixes
If the clause should be selectable, then move the clause before the general
clause:
```dart
void f() {
try {
} on String {
} catch (e) {
}
}
```
If the clause doesn't need to be selectable, then remove it:
```dart
void f() {
try {
} catch (e) {
}
}
```
DEAD_CODE_ON_CATCH_SUBTYPE:
problemMessage: "Dead code: This on-catch block won't be executed because '{0}' is a subtype of '{1}' and hence will have been caught already."
correctionMessage: Try reordering the catch clauses so that this block can be reached, or removing the unreachable catch clause.
hasPublishedDocs: true
comment: |-
Dead code is code that is never reached. This case covers cases where the
user has an on-catch clause such as `on A catch (e)`, where a supertype of
`A` was already caught.
Parameters:
0: name of the subtype
1: name of the supertype
documentation: |-
#### Description
The analyzer produces this diagnostic when a `catch` clause is found that
can't be executed because it is after a `catch` clause that catches either
the same type or a supertype of the clause's type. The first `catch` clause
that matches the thrown object is selected, and the earlier clause always
matches anything matchable by the highlighted clause, so the highlighted
clause will never be selected.
#### Example
The following code produces this diagnostic:
```dart
void f() {
try {
} on num {
} [!on int {
}!]
}
```
#### Common fixes
If the clause should be selectable, then move the clause before the general
clause:
```dart
void f() {
try {
} on int {
} on num {
}
}
```
If the clause doesn't need to be selectable, then remove it:
```dart
void f() {
try {
} on num {
}
}
```
DEPRECATED_EXTENDS_FUNCTION:
sharedName: DEPRECATED_SUBTYPE_OF_FUNCTION
problemMessage: "Extending 'Function' is deprecated."
correctionMessage: "Try removing 'Function' from the 'extends' clause."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the class `Function` is used in
either the `extends`, `implements`, or `with` clause of a class or mixin.
Using the class `Function` in this way has no semantic value, so it's
effectively dead code.
#### Example
The following code produces this diagnostic because `Function` is used as
the superclass of `F`:
```dart
class F extends [!Function!] {}
```
#### Common fixes
Remove the class `Function` from whichever clause it's in, and remove the
whole clause if `Function` is the only type in the clause:
```dart
class F {}
```
DEPRECATED_IMPLEMENTS_FUNCTION:
sharedName: DEPRECATED_SUBTYPE_OF_FUNCTION
problemMessage: "Implementing 'Function' has no effect."
correctionMessage: "Try removing 'Function' from the 'implements' clause."
hasPublishedDocs: true
comment: No parameters.
DEPRECATED_MIXIN_FUNCTION:
sharedName: DEPRECATED_SUBTYPE_OF_FUNCTION
problemMessage: "Mixing in 'Function' is deprecated."
correctionMessage: "Try removing 'Function' from the 'with' clause."
hasPublishedDocs: true
comment: No parameters.
DEPRECATED_NEW_IN_COMMENT_REFERENCE:
problemMessage: "Using the 'new' keyword in a comment reference is deprecated."
correctionMessage: Try referring to a constructor by its name.
comment: No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a comment reference (the name
of a declaration enclosed in square brackets in a documentation comment)
uses the keyword `new` to refer to a constructor. This form is deprecated.
#### Examples
The following code produces this diagnostic because the unnamed
constructor is being referenced using `new C`:
```dart
/// See [[!new!] C].
class C {
C();
}
```
The following code produces this diagnostic because the constructor named
`c` is being referenced using `new C.c`:
```dart
/// See [[!new!] C.c].
class C {
C.c();
}
```
#### Common fixes
If you're referencing a named constructor, then remove the keyword `new`:
```dart
/// See [C.c].
class C {
C.c();
}
```
If you're referencing the unnamed constructor, then remove the keyword
`new` and append `.new` after the class name:
```dart
/// See [C.new].
class C {
C.c();
}
```
DUPLICATE_EXPORT:
problemMessage: Duplicate export.
correctionMessage: Try removing all but one export of the library.
hasPublishedDocs: true
comment: |-
Duplicate exports.
No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when an export directive is found
that is the same as an export before it in the file. The second export
doesn't add value and should be removed.
#### Example
The following code produces this diagnostic because the same library is
being exported twice:
```dart
export 'package:meta/meta.dart';
export [!'package:meta/meta.dart'!];
```
#### Common fixes
Remove the unnecessary export:
```dart
export 'package:meta/meta.dart';
```
DUPLICATE_HIDDEN_NAME:
problemMessage: Duplicate hidden name.
correctionMessage: Try removing the repeated name from the list of hidden members.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a name occurs multiple times in
a `hide` clause. Repeating the name is unnecessary.
#### Example
The following code produces this diagnostic because the name `min` is
hidden more than once:
```dart
import 'dart:math' hide min, [!min!];
var x = pi;
```
#### Common fixes
If the name was mistyped in one or more places, then correct the mistyped
names:
```dart
import 'dart:math' hide max, min;
var x = pi;
```
If the name wasn't mistyped, then remove the unnecessary name from the
list:
```dart
import 'dart:math' hide min;
var x = pi;
```
DUPLICATE_IGNORE:
problemMessage: "The diagnostic '{0}' doesn't need to be ignored here because it's already being ignored."
correctionMessage: Try removing the name from the list, or removing the whole comment if this is the only name in the list.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the diagnostic being ignored
documentation: |-
#### Description
The analyzer produces this diagnostic when a diagnostic name appears in an
`ignore` comment, but the diagnostic is already being ignored, either
because it's already included in the same `ignore` comment or because it
appears in an `ignore-in-file` comment.
#### Examples
The following code produces this diagnostic because the diagnostic named
`unused_local_variable` is already being ignored for the whole file so it
doesn't need to be ignored on a specific line:
```dart
// ignore_for_file: unused_local_variable
void f() {
// ignore: [!unused_local_variable!]
var x = 0;
}
```
The following code produces this diagnostic because the diagnostic named
`unused_local_variable` is being ignored twice on the same line:
```dart
void f() {
// ignore: unused_local_variable, [!unused_local_variable!]
var x = 0;
}
```
#### Common fixes
Remove the ignore comment, or remove the unnecessary diagnostic name if the
ignore comment is ignoring more than one diagnostic:
```dart
// ignore_for_file: unused_local_variable
void f() {
var x = 0;
}
```
DUPLICATE_IMPORT:
problemMessage: Duplicate import.
correctionMessage: Try removing all but one import of the library.
hasPublishedDocs: true
comment: |-
Duplicate imports.
No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when an import directive is found
that is the same as an import before it in the file. The second import
doesn't add value and should be removed.
#### Example
The following code produces this diagnostic:
```dart
import 'package:meta/meta.dart';
import [!'package:meta/meta.dart'!];
@sealed class C {}
```
#### Common fixes
Remove the unnecessary import:
```dart
import 'package:meta/meta.dart';
@sealed class C {}
```
DUPLICATE_SHOWN_NAME:
problemMessage: Duplicate shown name.
correctionMessage: Try removing the repeated name from the list of shown members.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a name occurs multiple times in
a `show` clause. Repeating the name is unnecessary.
#### Example
The following code produces this diagnostic because the name `min` is shown
more than once:
```dart
import 'dart:math' show min, [!min!];
var x = min(2, min(0, 1));
```
#### Common fixes
If the name was mistyped in one or more places, then correct the mistyped
names:
```dart
import 'dart:math' show max, min;
var x = max(2, min(0, 1));
```
If the name wasn't mistyped, then remove the unnecessary name from the
list:
```dart
import 'dart:math' show min;
var x = min(2, min(0, 1));
```
EQUAL_ELEMENTS_IN_SET:
problemMessage: "Two elements in a set literal shouldn't be equal."
correctionMessage: Change or remove the duplicate element.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when an element in a non-constant set
is the same as a previous element in the same set. If two elements are the
same, then the second value is ignored, which makes having both elements
pointless and likely signals a bug.
#### Example
The following code produces this diagnostic because the element `1` appears
twice:
```dart
const a = 1;
const b = 1;
var s = <int>{a, [!b!]};
```
#### Common fixes
If both elements should be included in the set, then change one of the
elements:
```dart
const a = 1;
const b = 2;
var s = <int>{a, b};
```
If only one of the elements is needed, then remove the one that isn't
needed:
```dart
const a = 1;
var s = <int>{a};
```
Note that literal sets preserve the order of their elements, so the choice
of which element to remove might affect the order in which elements are
returned by an iterator.
EQUAL_KEYS_IN_MAP:
problemMessage: "Two keys in a map literal shouldn't be equal."
correctionMessage: Change or remove the duplicate key.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a key in a non-constant map is
the same as a previous key in the same map. If two keys are the same, then
the second value overwrites the first value, which makes having both pairs
pointless and likely signals a bug.
#### Example
The following code produces this diagnostic because the keys `a` and `b`
have the same value:
```dart
const a = 1;
const b = 1;
var m = <int, String>{a: 'a', [!b!]: 'b'};
```
#### Common fixes
If both entries should be included in the map, then change one of the keys:
```dart
const a = 1;
const b = 2;
var m = <int, String>{a: 'a', b: 'b'};
```
If only one of the entries is needed, then remove the one that isn't
needed:
```dart
const a = 1;
var m = <int, String>{a: 'a'};
```
Note that literal maps preserve the order of their entries, so the choice
of which entry to remove might affect the order in which the keys and
values are returned by an iterator.
INFERENCE_FAILURE_ON_COLLECTION_LITERAL:
problemMessage: "The type argument(s) of '{0}' can't be inferred."
correctionMessage: "Use explicit type argument(s) for '{0}'."
comment: |-
When "strict-inference" is enabled, collection literal types must be
inferred via the context type, or have type arguments.
Parameters:
0: the name of the collection
INFERENCE_FAILURE_ON_FUNCTION_INVOCATION:
problemMessage: "The type argument(s) of the function '{0}' can't be inferred."
correctionMessage: "Use explicit type argument(s) for '{0}'."
comment: |-
When "strict-inference" is enabled, types in function invocations must be
inferred via the context type, or have type arguments.
Parameters:
0: the name of the function
INFERENCE_FAILURE_ON_FUNCTION_RETURN_TYPE:
problemMessage: "The return type of '{0}' cannot be inferred."
correctionMessage: "Declare the return type of '{0}'."
comment: |-
When "strict-inference" is enabled, recursive local functions, top-level
functions, methods, and function-typed function parameters must all
specify a return type. See the strict-inference resource:
https://github.com/dart-lang/language/blob/master/resources/type-system/strict-inference.md
Parameters:
0: the name of the function or method
INFERENCE_FAILURE_ON_GENERIC_INVOCATION:
problemMessage: "The type argument(s) of the generic function type '{0}' can't be inferred."
correctionMessage: "Use explicit type argument(s) for '{0}'."
comment: |-
When "strict-inference" is enabled, types in function invocations must be
inferred via the context type, or have type arguments.
Parameters:
0: the name of the type
INFERENCE_FAILURE_ON_INSTANCE_CREATION:
problemMessage: "The type argument(s) of the constructor '{0}' can't be inferred."
correctionMessage: "Use explicit type argument(s) for '{0}'."
comment: |-
When "strict-inference" is enabled, types in instance creation
(constructor calls) must be inferred via the context type, or have type
arguments.
Parameters:
0: the name of the constructor
INFERENCE_FAILURE_ON_UNINITIALIZED_VARIABLE:
problemMessage: "The type of {0} can't be inferred without either a type or initializer."
correctionMessage: Try specifying the type of the variable.
comment: |-
When "strict-inference" in enabled, uninitialized variables must be
declared with a specific type.
Parameters:
0: the name of the variable
INFERENCE_FAILURE_ON_UNTYPED_PARAMETER:
problemMessage: "The type of {0} can't be inferred; a type must be explicitly provided."
correctionMessage: Try specifying the type of the parameter.
comment: |-
When "strict-inference" in enabled, function parameters must be
declared with a specific type, or inherit a type.
Parameters:
0: the name of the parameter
INVALID_ANNOTATION_TARGET:
problemMessage: "The annotation '{0}' can only be used on {1}."
comment: |-
Parameters:
0: the name of the annotation
1: the list of valid targets
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when an annotation is applied to a
kind of declaration that it doesn't support.
#### Example
The following code produces this diagnostic because the `optionalTypeArgs`
annotation isn't defined to be valid for top-level variables:
```dart
import 'package:meta/meta.dart';
@[!optionalTypeArgs!]
int x = 0;
```
#### Common fixes
Remove the annotation from the declaration.
INVALID_EXPORT_OF_INTERNAL_ELEMENT:
problemMessage: "The member '{0}' can't be exported as a part of a package's public API."
correctionMessage: "Try using a hide clause to hide '{0}'."
comment: |-
Parameters:
0: the name of the element
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a [public library][] exports a
declaration that is marked with the [`internal`][meta-internal]
annotation.
#### Example
Given a file `a.dart` in the `src` directory that contains:
```dart
%uri="lib/src/a.dart"
import 'package:meta/meta.dart';
@internal class One {}
```
The following code, when found in a [public library][] produces this
diagnostic because the `export` directive is exporting a name that is only
intended to be used internally:
```dart
[!export 'src/a.dart';!]
```
#### Common fixes
If the export is needed, then add a `hide` clause to hide the internal
names:
```dart
export 'src/a.dart' hide One;
```
If the export isn't needed, then remove it.
INVALID_EXPORT_OF_INTERNAL_ELEMENT_INDIRECTLY:
problemMessage: "The member '{0}' can't be exported as a part of a package's public API, but is indirectly exported as part of the signature of '{1}'."
correctionMessage: "Try using a hide clause to hide '{0}'."
comment: |-
Parameters:
0: the name of the element
1: ?
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a [public library][] exports a
top-level function with a return type or at least one parameter type that
is marked with the [`internal`][meta-internal] annotation.
#### Example
Given a file `a.dart` in the `src` directory that contains the
following:
```dart
%uri="lib/src/a.dart"
import 'package:meta/meta.dart';
@internal
typedef IntFunction = int Function();
int f(IntFunction g) => g();
```
The following code produces this diagnostic because the function `f` has a
parameter of type `IntFunction`, and `IntFunction` is only intended to be
used internally:
```dart
[!export 'src/a.dart' show f;!]
```
#### Common fixes
If the function must be public, then make all the types in the function's
signature public types.
If the function doesn't need to be exported, then stop exporting it,
either by removing it from the `show` clause, adding it to the `hide`
clause, or by removing the export.
INVALID_FACTORY_ANNOTATION:
problemMessage: Only methods can be annotated as factories.
comment: |-
This warning is generated anywhere a @factory annotation is associated
with anything other than a method.
INVALID_FACTORY_METHOD_DECL:
problemMessage: "Factory method '{0}' must have a return type."
comment: |-
Parameters:
0: The name of the method
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a method that is annotated with
the [`factory`][meta-factory] annotation has a return type of `void`.
#### Example
The following code produces this diagnostic because the method `createC`
is annotated with the [`factory`][meta-factory] annotation but doesn't
return any value:
```dart
import 'package:meta/meta.dart';
class Factory {
@factory
void [!createC!]() {}
}
class C {}
```
#### Common fixes
Change the return type to something other than `void`:
```dart
import 'package:meta/meta.dart';
class Factory {
@factory
C createC() => C();
}
class C {}
```
INVALID_FACTORY_METHOD_IMPL:
problemMessage: "Factory method '{0}' doesn't return a newly allocated object."
comment: |-
Parameters:
0: the name of the method
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a method that is annotated with
the [`factory`][meta-factory] annotation doesn't return a newly allocated
object.
#### Example
The following code produces this diagnostic because the method `createC`
returns the value of a field rather than a newly created instance of `C`:
```dart
import 'package:meta/meta.dart';
class Factory {
C c = C();
@factory
C [!createC!]() => c;
}
class C {}
```
#### Common fixes
Change the method to return a newly created instance of the return type:
```dart
import 'package:meta/meta.dart';
class Factory {
@factory
C createC() => C();
}
class C {}
```
INVALID_IMMUTABLE_ANNOTATION:
problemMessage: Only classes can be annotated as being immutable.
comment: |-
This warning is generated anywhere an @immutable annotation is associated
with anything other than a class.
INVALID_INTERNAL_ANNOTATION:
problemMessage: "Only public elements in a package's private API can be annotated as being internal."
comment: |-
No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a declaration is annotated with
the [`internal`][meta-internal] annotation and that declaration is either
in a [public library][] or has a private name.
#### Example
The following code, when in a [public library][], produces this diagnostic
because the [`internal`][meta-internal] annotation can't be applied to
declarations in a [public library][]:
```dart
import 'package:meta/meta.dart';
[!@internal!]
class C {}
```
The following code, whether in a public or internal library, produces this
diagnostic because the [`internal`][meta-internal] annotation can't be
applied to declarations with private names:
```dart
import 'package:meta/meta.dart';
[!@internal!]
class _C {}
void f(_C c) {}
```
#### Common fixes
If the declaration has a private name, then remove the annotation:
```dart
class _C {}
void f(_C c) {}
```
If the declaration has a public name and is intended to be internal to the
package, then move the annotated declaration into an internal library (in
other words, a library inside the `src` directory).
Otherwise, remove the use of the annotation:
```dart
class C {}
```
INVALID_LANGUAGE_VERSION_OVERRIDE_GREATER:
sharedName: INVALID_LANGUAGE_VERSION_OVERRIDE
problemMessage: "The language version override can't specify a version greater than the latest known language version: {0}.{1}."
correctionMessage: Try removing the language version override.
hasPublishedDocs: true
comment: |-
Parameters:
0: the latest major version
1: the latest minor version
INVALID_LANGUAGE_VERSION_OVERRIDE_AT_SIGN:
sharedName: INVALID_LANGUAGE_VERSION_OVERRIDE
problemMessage: "The Dart language version override number must begin with '@dart'."
correctionMessage: "Specify a Dart language version override with a comment like '// @dart = 2.0'."
comment: |-
No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a comment that appears to be an
attempt to specify a language version override doesn't conform to the
requirements for such a comment. For more information, see
[Per-library language version selection](https://dart.dev/guides/language/evolution#per-library-language-version-selection).
#### Example
The following code produces this diagnostic because the word `dart` must
be lowercase in such a comment and because there's no equal sign between
the word `dart` and the version number:
```dart
[!// @Dart 2.13!]
```
#### Common fixes
If the comment is intended to be a language version override, then change
the comment to follow the correct format:
```dart
// @dart = 2.13
```
INVALID_LANGUAGE_VERSION_OVERRIDE_LOCATION:
sharedName: INVALID_LANGUAGE_VERSION_OVERRIDE
problemMessage: The language version override must be specified before any declaration or directive.
correctionMessage: Try moving the language version override to the top of the file.
hasPublishedDocs: true
INVALID_LANGUAGE_VERSION_OVERRIDE_LOWER_CASE:
sharedName: INVALID_LANGUAGE_VERSION_OVERRIDE
problemMessage: "The Dart language version override comment must be specified with the word 'dart' in all lower case."
correctionMessage: "Specify a Dart language version override with a comment like '// @dart = 2.0'."
comment: |-
No parameters.
hasPublishedDocs: true
INVALID_LANGUAGE_VERSION_OVERRIDE_NUMBER:
sharedName: INVALID_LANGUAGE_VERSION_OVERRIDE
problemMessage: "The Dart language version override comment must be specified with a version number, like '2.0', after the '=' character."
correctionMessage: "Specify a Dart language version override with a comment like '// @dart = 2.0'."
comment: |-
No parameters.
hasPublishedDocs: true
INVALID_LANGUAGE_VERSION_OVERRIDE_PREFIX:
sharedName: INVALID_LANGUAGE_VERSION_OVERRIDE
problemMessage: "The Dart language version override number can't be prefixed with a letter."
correctionMessage: "Specify a Dart language version override with a comment like '// @dart = 2.0'."
comment: |-
No parameters.
hasPublishedDocs: true
INVALID_LANGUAGE_VERSION_OVERRIDE_TRAILING_CHARACTERS:
sharedName: INVALID_LANGUAGE_VERSION_OVERRIDE
problemMessage: "The Dart language version override comment can't be followed by any non-whitespace characters."
correctionMessage: "Specify a Dart language version override with a comment like '// @dart = 2.0'."
comment: |-
No parameters.
hasPublishedDocs: true
INVALID_LANGUAGE_VERSION_OVERRIDE_TWO_SLASHES:
sharedName: INVALID_LANGUAGE_VERSION_OVERRIDE
problemMessage: The Dart language version override comment must be specified with exactly two slashes.
correctionMessage: "Specify a Dart language version override with a comment like '// @dart = 2.0'."
comment: |-
No parameters.
hasPublishedDocs: true
INVALID_LANGUAGE_VERSION_OVERRIDE_EQUALS:
sharedName: INVALID_LANGUAGE_VERSION_OVERRIDE
problemMessage: "The Dart language version override comment must be specified with an '=' character."
correctionMessage: "Specify a Dart language version override with a comment like '// @dart = 2.0'."
comment: |-
No parameters.
hasPublishedDocs: true
INVALID_LITERAL_ANNOTATION:
problemMessage: Only const constructors can have the `@literal` annotation.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the [`literal`][meta-literal]
annotation is applied to anything other than a const constructor.
#### Examples
The following code produces this diagnostic because the constructor isn't
a `const` constructor:
```dart
import 'package:meta/meta.dart';
class C {
[!@literal!]
C();
}
```
The following code produces this diagnostic because `x` isn't a
constructor:
```dart
import 'package:meta/meta.dart';
[!@literal!]
var x;
```
#### Common fixes
If the annotation is on a constructor and the constructor should always be
invoked with `const`, when possible, then mark the constructor with the
`const` keyword:
```dart
import 'package:meta/meta.dart';
class C {
@literal
const C();
}
```
If the constructor can't be marked as `const`, then remove the annotation.
If the annotation is on anything other than a constructor, then remove the
annotation:
```dart
var x;
```
INVALID_NON_VIRTUAL_ANNOTATION:
problemMessage: "The annotation '@nonVirtual' can only be applied to a concrete instance member."
correctionMessage: Try removing '@nonVirtual'.
hasPublishedDocs: true
comment: |-
This warning is generated anywhere where `@nonVirtual` annotates something
other than a non-abstract instance member in a class or mixin.
No Parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the `nonVirtual` annotation is
found on a declaration other than a member of a class, mixin, or enum, or
if the member isn't a concrete instance member.
#### Examples
The following code produces this diagnostic because the annotation is on a
class declaration rather than a member inside the class:
```dart
import 'package:meta/meta.dart';
[!@nonVirtual!]
class C {}
```
The following code produces this diagnostic because the method `m` is an
abstract method:
```dart
import 'package:meta/meta.dart';
abstract class C {
[!@nonVirtual!]
void m();
}
```
The following code produces this diagnostic because the method `m` is a
static method:
```dart
import 'package:meta/meta.dart';
abstract class C {
[!@nonVirtual!]
static void m() {}
}
```
#### Common fixes
If the declaration isn't a member of a class, mixin, or enum, then remove
the annotation:
```dart
class C {}
```
If the member is intended to be a concrete instance member, then make it
so:
```dart
import 'package:meta/meta.dart';
abstract class C {
@nonVirtual
void m() {}
}
```
If the member is not intended to be a concrete instance member, then
remove the annotation:
```dart
abstract class C {
static void m() {}
}
```
INVALID_OVERRIDE_OF_NON_VIRTUAL_MEMBER:
problemMessage: "The member '{0}' is declared non-virtual in '{1}' and can't be overridden in subclasses."
hasPublishedDocs: true
comment: |-
This warning is generated anywhere where an instance member annotated with
`@nonVirtual` is overridden in a subclass.
Parameters:
0: the name of the member
1: the name of the defining class
documentation: |-
#### Description
The analyzer produces this diagnostic when a member of a class, mixin, or
enum overrides a member that has the `@nonVirtual` annotation on it.
#### Example
The following code produces this diagnostic because the method `m` in `B`
overrides the method `m` in `A`, and the method `m` in `A` is annotated
with the `@nonVirtual` annotation:
```dart
import 'package:meta/meta.dart';
class A {
@nonVirtual
void m() {}
}
class B extends A {
@override
void [!m!]() {}
}
```
#### Common fixes
If the annotation on the method in the superclass is correct (the method
in the superclass is not intended to be overridden), then remove or rename
the overriding method:
```dart
import 'package:meta/meta.dart';
class A {
@nonVirtual
void m() {}
}
class B extends A {}
```
If the method in the superclass is intended to be overridden, then remove
the `@nonVirtual` annotation:
```dart
class A {
void m() {}
}
class B extends A {
@override
void m() {}
}
```
INVALID_REQUIRED_NAMED_PARAM:
problemMessage: "The type parameter '{0}' is annotated with @required but only named parameters without a default value can be annotated with it."
correctionMessage: Remove @required.
comment: |-
This warning is generated anywhere where `@required` annotates a named
parameter with a default value.
Parameters:
0: the name of the member
INVALID_REQUIRED_OPTIONAL_POSITIONAL_PARAM:
problemMessage: "Incorrect use of the annotation @required on the optional positional parameter '{0}'. Optional positional parameters cannot be required."
correctionMessage: Remove @required.
comment: |-
This warning is generated anywhere where `@required` annotates an optional
positional parameter.
Parameters:
0: the name of the member
INVALID_REQUIRED_POSITIONAL_PARAM:
problemMessage: "Redundant use of the annotation @required on the required positional parameter '{0}'."
correctionMessage: Remove @required.
comment: |-
This warning is generated anywhere where `@required` annotates a
non-optional positional parameter.
Parameters:
0: the name of the member
INVALID_USE_OF_INTERNAL_MEMBER:
problemMessage: "The member '{0}' can only be used within its package."
comment: |-
Parameters:
0: the name of the member
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a reference to a declaration
that is annotated with the [`internal`][meta-internal] annotation is found
outside the package containing the declaration.
#### Example
Given a package `p` that defines a library containing a declaration marked
with the [`internal`][meta-internal] annotation:
```dart
%uri="package:p/src/p.dart"
import 'package:meta/meta.dart';
@internal
class C {}
```
The following code produces this diagnostic because it's referencing the
class `C`, which isn't intended to be used outside the package `p`:
```dart
import 'package:p/src/p.dart';
void f([!C!] c) {}
```
#### Common fixes
Remove the reference to the internal declaration.
INVALID_USE_OF_PROTECTED_MEMBER:
problemMessage: "The member '{0}' can only be used within instance members of subclasses of '{1}'."
comment: |-
This warning is generated anywhere where a member annotated with
`@protected` is used outside of an instance member of a subclass.
Parameters:
0: the name of the member
1: the name of the defining class
INVALID_USE_OF_VISIBLE_FOR_OVERRIDING_MEMBER:
problemMessage: "The member '{0}' can only be used for overriding."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the member
documentation: |-
#### Description
The analyzer produces this diagnostic when an instance member that is
annotated with [`visibleForOverriding`][meta-visibleForOverriding] is
referenced outside the library in which it's declared for any reason other
than to override it.
#### Example
Given a file `a.dart` containing the following declaration:
```dart
%uri="lib/a.dart"
import 'package:meta/meta.dart';
class A {
@visibleForOverriding
void a() {}
}
```
The following code produces this diagnostic because the method `m` is being
invoked even though the only reason it's public is to allow it to be
overridden:
```dart
import 'a.dart';
class B extends A {
void b() {
[!a!]();
}
}
```
#### Common fixes
Remove the invalid use of the member.
INVALID_USE_OF_VISIBLE_FOR_TEMPLATE_MEMBER:
problemMessage: "The member '{0}' can only be used within '{1}' or a template library."
comment: |-
This warning is generated anywhere where a member annotated with
`@visibleForTemplate` is used outside of a "template" Dart file.
Parameters:
0: the name of the member
1: the name of the defining class
INVALID_USE_OF_VISIBLE_FOR_TESTING_MEMBER:
problemMessage: "The member '{0}' can only be used within '{1}' or a test."
hasPublishedDocs: true
comment: |-
This warning is generated anywhere where a member annotated with
`@visibleForTesting` is used outside the defining library, or a test.
Parameters:
0: the name of the member
1: the name of the defining class
documentation: |-
#### Description
The analyzer produces this diagnostic when a member annotated with
`@visibleForTesting` is referenced anywhere other than the library in
which it is declared or in a library in the `test` directory.
#### Example
Given a file `c.dart` that contains the following:
```dart
%uri="lib/c.dart"
import 'package:meta/meta.dart';
class C {
@visibleForTesting
void m() {}
}
```
The following code, when not inside the `test` directory, produces this
diagnostic because the method `m` is marked as being visible only for
tests:
```dart
import 'c.dart';
void f(C c) {
c.[!m!]();
}
```
#### Common fixes
If the annotated member should not be referenced outside of tests, then
remove the reference:
```dart
import 'c.dart';
void f(C c) {}
```
If it's OK to reference the annotated member outside of tests, then remove
the annotation:
```dart
class C {
void m() {}
}
```
INVALID_VISIBILITY_ANNOTATION:
problemMessage: "The member '{0}' is annotated with '{1}', but this annotation is only meaningful on declarations of public members."
hasPublishedDocs: true
comment: |-
This warning is generated anywhere where a private declaration is
annotated with `@visibleForTemplate` or `@visibleForTesting`.
Parameters:
0: the name of the member
1: the name of the annotation
documentation: |-
#### Description
The analyzer produces this diagnostic when either the `visibleForTemplate`
or [`visibleForTesting`][meta-visibleForTesting] annotation is applied to
a non-public declaration.
#### Example
The following code produces this diagnostic:
```dart
import 'package:meta/meta.dart';
[!@visibleForTesting!]
void _someFunction() {}
void f() => _someFunction();
```
#### Common fixes
If the declaration doesn't need to be used by test code, then remove the
annotation:
```dart
void _someFunction() {}
void f() => _someFunction();
```
If it does, then make it public:
```dart
import 'package:meta/meta.dart';
@visibleForTesting
void someFunction() {}
void f() => someFunction();
```
INVALID_VISIBLE_FOR_OVERRIDING_ANNOTATION:
problemMessage: "The annotation 'visibleForOverriding' can only be applied to a public instance member that can be overridden."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when anything other than a public
instance member of a class is annotated with
[`visibleForOverriding`][meta-visibleForOverriding]. Because only public
instance members can be overridden outside the defining library, there's
no value to annotating any other declarations.
#### Example
The following code produces this diagnostic because the annotation is on a
class, and classes can't be overridden:
```dart
import 'package:meta/meta.dart';
[!@visibleForOverriding!]
class C {}
```
#### Common fixes
Remove the annotation:
```dart
class C {}
```
INVALID_VISIBLE_OUTSIDE_TEMPLATE_ANNOTATION:
problemMessage: "The annotation 'visibleOutsideTemplate' can only be applied to a member of a class, enum, or mixin that is annotated with 'visibleForTemplate'."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the `@visibleOutsideTemplate`
annotation is used incorrectly. This annotation is only meant to annotate
members of a class, enum, or mixin that has the `@visibleForTemplate`
annotation, to opt those members out of the visibility restrictions that
`@visibleForTemplate` imposes.
#### Examples
The following code produces this diagnostic because there is no
`@visibleForTemplate` annotation at the class level:
```dart
import 'package:angular_meta/angular_meta.dart';
class C {
[!@visibleOutsideTemplate!]
int m() {
return 1;
}
}
```
The following code produces this diagnostic because the annotation is on
a class declaration, not a member of a class, enum, or mixin:
```dart
import 'package:angular_meta/angular_meta.dart';
[!@visibleOutsideTemplate!]
class C {}
```
#### Common fixes
If the class is only visible so that templates can reference it, then add
the `@visibleForTemplate` annotation to the class:
```dart
import 'package:angular_meta/angular_meta.dart';
@visibleForTemplate
class C {
@visibleOutsideTemplate
int m() {
return 1;
}
}
```
If the `@visibleOutsideTemplate` annotation is on anything other than a
member of a class, enum, or mixin with the `@visibleForTemplate`
annotation, remove the annotation:
```dart
class C {}
```
RETURN_TYPE_INVALID_FOR_CATCH_ERROR:
sharedName: INVALID_RETURN_TYPE_FOR_CATCH_ERROR
problemMessage: "The return type '{0}' isn't assignable to '{1}', as required by 'Future.catchError'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the return type of the function
1: the expected return type as defined by the type of the Future
RETURN_OF_INVALID_TYPE_FROM_CATCH_ERROR:
sharedName: INVALID_RETURN_TYPE_FOR_CATCH_ERROR
problemMessage: "A value of type '{0}' can't be returned by the 'onError' handler because it must be assignable to '{1}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the return type as declared in the return statement
1: the expected return type as defined by the type of the Future
documentation: |-
#### Description
The analyzer produces this diagnostic when an invocation of
`Future.catchError` has an argument whose return type isn't compatible with
the type returned by the instance of `Future`. At runtime, the method
`catchError` attempts to return the value from the callback as the result
of the future, which results in another exception being thrown.
#### Examples
The following code produces this diagnostic because `future` is declared to
return an `int` while `callback` is declared to return a `String`, and
`String` isn't a subtype of `int`:
```dart
void f(Future<int> future, String Function(dynamic, StackTrace) callback) {
future.catchError([!callback!]);
}
```
The following code produces this diagnostic because the closure being
passed to `catchError` returns an `int` while `future` is declared to
return a `String`:
```dart
void f(Future<String> future) {
future.catchError((error, stackTrace) => [!3!]);
}
```
#### Common fixes
If the instance of `Future` is declared correctly, then change the callback
to match:
```dart
void f(Future<int> future, int Function(dynamic, StackTrace) callback) {
future.catchError(callback);
}
```
If the declaration of the instance of `Future` is wrong, then change it to
match the callback:
```dart
void f(Future<String> future, String Function(dynamic, StackTrace) callback) {
future.catchError(callback);
}
```
INVALID_REOPEN_ANNOTATION:
problemMessage: "The annotation '@reopen' can only be applied to a class that opens capabilities that the supertype intentionally disallows."
correctionMessage: Try removing the '@reopen' annotation.
comment: |-
This warning is generated anywhere where `@reopen` annotates a class which
did not reopen any type.
No parameters.
INVALID_SEALED_ANNOTATION:
problemMessage: "The annotation '@sealed' can only be applied to classes."
correctionMessage: Try removing the '@sealed' annotation.
hasPublishedDocs: true
comment: |-
This warning is generated anywhere where `@sealed` annotates something
other than a class.
No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a declaration other than a
class declaration has the `@sealed` annotation on it.
#### Example
The following code produces this diagnostic because the `@sealed`
annotation is on a method declaration:
```dart
import 'package:meta/meta.dart';
class A {
[!@sealed!]
void m() {}
}
```
#### Common fixes
Remove the annotation:
```dart
class A {
void m() {}
}
```
MISSING_OVERRIDE_OF_MUST_BE_OVERRIDDEN_ONE:
sharedName: MISSING_OVERRIDE_OF_MUST_BE_OVERRIDDEN
problemMessage: "Missing concrete implementation of '{0}'."
correctionMessage: Try overriding the missing member.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the member
documentation: |-
#### Description
The analyzer produces this diagnostic when an instance member that has the
`@mustBeOverridden` annotation isn't overridden in a subclass.
#### Example
The following code produces this diagnostic because the class `B` doesn't
have an override of the inherited method `A.m` when `A.m` is annotated
with `@mustBeOverridden`:
```dart
import 'package:meta/meta.dart';
class A {
@mustBeOverridden
void m() {}
}
class [!B!] extends A {}
```
#### Common fixes
If the annotation is appropriate for the member, then override the member
in the subclass:
```dart
import 'package:meta/meta.dart';
class A {
@mustBeOverridden
void m() {}
}
class B extends A {
@override
void m() {}
}
```
If the annotation isn't appropriate for the member, then remove the
annotation:
```dart
class A {
void m() {}
}
class B extends A {}
```
MISSING_OVERRIDE_OF_MUST_BE_OVERRIDDEN_TWO:
sharedName: MISSING_OVERRIDE_OF_MUST_BE_OVERRIDDEN
problemMessage: "Missing concrete implementations of '{0}' and '{1}'."
correctionMessage: Try overriding the missing members.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the first member
1: the name of the second member
MISSING_OVERRIDE_OF_MUST_BE_OVERRIDDEN_THREE_PLUS:
sharedName: MISSING_OVERRIDE_OF_MUST_BE_OVERRIDDEN
problemMessage: "Missing concrete implementations of '{0}', '{1}', and {2} more."
correctionMessage: Try overriding the missing members.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the first member
1: the name of the second member
2: the number of additional missing members that aren't listed
MISSING_REQUIRED_PARAM:
problemMessage: "The parameter '{0}' is required."
hasPublishedDocs: true
comment: |-
Generates a warning for a constructor, function or method invocation where
a required parameter is missing.
Parameters:
0: the name of the parameter
documentation: |-
#### Description
The analyzer produces this diagnostic when a method or function with a
named parameter that is annotated as being required is invoked without
providing a value for the parameter.
#### Example
The following code produces this diagnostic because the named parameter `x`
is required:
```dart
%language=2.9
import 'package:meta/meta.dart';
void f({@required int x}) {}
void g() {
[!f!]();
}
```
#### Common fixes
Provide the required value:
```dart
%language=2.9
import 'package:meta/meta.dart';
void f({@required int x}) {}
void g() {
f(x: 2);
}
```
MISSING_REQUIRED_PARAM_WITH_DETAILS:
sharedName: MISSING_REQUIRED_PARAM
problemMessage: "The parameter '{0}' is required. {1}."
hasPublishedDocs: true
comment: |-
Generates a warning for a constructor, function or method invocation where
a required parameter is missing.
Parameters:
0: the name of the parameter
1: message details
MISSING_RETURN:
problemMessage: "This function has a return type of '{0}', but doesn't end with a return statement."
correctionMessage: "Try adding a return statement, or changing the return type to 'void'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the declared return type
documentation: |-
#### Description
Any function or method that doesn't end with either an explicit return or a
throw implicitly returns `null`. This is rarely the desired behavior. The
analyzer produces this diagnostic when it finds an implicit return.
#### Example
The following code produces this diagnostic because `f` doesn't end with a
return:
```dart
%language=2.9
int [!f!](int x) {
if (x < 0) {
return 0;
}
}
```
#### Common fixes
Add a `return` statement that makes the return value explicit, even if
`null` is the appropriate value.
MIXIN_ON_SEALED_CLASS:
problemMessage: "The class '{0}' shouldn't be used as a mixin constraint because it is sealed, and any class mixing in this mixin must have '{0}' as a superclass."
correctionMessage: Try composing with this class, or refer to its documentation for more information.
hasPublishedDocs: true
comment: |-
This warning is generated anywhere where a `@sealed` class is used as a
a superclass constraint of a mixin.
Parameters:
0: the name of the sealed class
documentation: |-
#### Description
The analyzer produces this diagnostic when the superclass constraint of a
mixin is a class from a different package that was marked as
[`sealed`][meta-sealed]. Classes that are sealed can't be extended,
implemented, mixed in, or used as a superclass constraint.
#### Example
If the package `p` defines a sealed class:
```dart
%uri="package:p/p.dart"
import 'package:meta/meta.dart';
@sealed
class C {}
```
Then, the following code, when in a package other than `p`, produces this
diagnostic:
```dart
import 'package:p/p.dart';
[!mixin M on C {}!]
```
#### Common fixes
If the classes that use the mixin don't need to be subclasses of the sealed
class, then consider adding a field and delegating to the wrapped instance
of the sealed class.
MUST_BE_IMMUTABLE:
problemMessage: "This class (or a class that this class inherits from) is marked as '@immutable', but one or more of its instance fields aren't final: {0}"
hasPublishedDocs: true
comment: |-
Generates a warning for classes that inherit from classes annotated with
`@immutable` but that are not immutable.
Parameters:
0: the name of the class
documentation: |-
#### Description
The analyzer produces this diagnostic when an immutable class defines one
or more instance fields that aren't final. A class is immutable if it's
marked as being immutable using the annotation
[`immutable`][meta-immutable] or if it's a subclass of an immutable class.
#### Example
The following code produces this diagnostic because the field `x` isn't
final:
```dart
import 'package:meta/meta.dart';
@immutable
class [!C!] {
int x;
C(this.x);
}
```
#### Common fixes
If instances of the class should be immutable, then add the keyword `final`
to all non-final field declarations:
```dart
import 'package:meta/meta.dart';
@immutable
class C {
final int x;
C(this.x);
}
```
If the instances of the class should be mutable, then remove the
annotation, or choose a different superclass if the annotation is
inherited:
```dart
class C {
int x;
C(this.x);
}
```
MUST_CALL_SUPER:
problemMessage: "This method overrides a method annotated as '@mustCallSuper' in '{0}', but doesn't invoke the overridden method."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the class declaring the overridden method
documentation: |-
#### Description
The analyzer produces this diagnostic when a method that overrides a method
that is annotated as [`mustCallSuper`][meta-mustCallSuper] doesn't invoke
the overridden method as required.
#### Example
The following code produces this diagnostic because the method `m` in `B`
doesn't invoke the overridden method `m` in `A`:
```dart
import 'package:meta/meta.dart';
class A {
@mustCallSuper
m() {}
}
class B extends A {
@override
[!m!]() {}
}
```
#### Common fixes
Add an invocation of the overridden method in the overriding method:
```dart
import 'package:meta/meta.dart';
class A {
@mustCallSuper
m() {}
}
class B extends A {
@override
m() {
super.m();
}
}
```
NON_CONST_CALL_TO_LITERAL_CONSTRUCTOR_USING_NEW:
sharedName: NON_CONST_CALL_TO_LITERAL_CONSTRUCTOR
problemMessage: "This instance creation must be 'const', because the {0} constructor is marked as '@literal'."
correctionMessage: "Try replacing the 'new' keyword with 'const'."
hasPublishedDocs: true
comment: |-
Generate a warning for non-const instance creation (with the `new` keyword)
using a constructor annotated with `@literal`.
Parameters:
0: the name of the class defining the annotated constructor
NON_CONST_CALL_TO_LITERAL_CONSTRUCTOR:
problemMessage: "This instance creation must be 'const', because the {0} constructor is marked as '@literal'."
correctionMessage: "Try adding a 'const' keyword."
hasPublishedDocs: true
comment: |-
Generates a warning for non-const instance creation using a constructor
annotated with `@literal`.
Parameters:
0: the name of the class defining the annotated constructor
documentation: |-
#### Description
The analyzer produces this diagnostic when a constructor that has the
[`literal`][meta-literal] annotation is invoked without using the `const`
keyword, but all of the arguments to the constructor are constants. The
annotation indicates that the constructor should be used to create a
constant value whenever possible.
#### Example
The following code produces this diagnostic:
```dart
import 'package:meta/meta.dart';
class C {
@literal
const C();
}
C f() => [!C()!];
```
#### Common fixes
Add the keyword `const` before the constructor invocation:
```dart
import 'package:meta/meta.dart';
class C {
@literal
const C();
}
void f() => const C();
```
NULLABLE_TYPE_IN_CATCH_CLAUSE:
problemMessage: "A potentially nullable type can't be used in an 'on' clause because it isn't valid to throw a nullable expression."
correctionMessage: Try using a non-nullable type.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the type following `on` in a
`catch` clause is a nullable type. It isn't valid to specify a nullable
type because it isn't possible to catch `null` (because it's a runtime
error to throw `null`).
#### Example
The following code produces this diagnostic because the exception type is
specified to allow `null` when `null` can't be thrown:
```dart
void f() {
try {
// ...
} on [!FormatException?!] {
}
}
```
#### Common fixes
Remove the question mark from the type:
```dart
void f() {
try {
// ...
} on FormatException {
}
}
```
NULL_ARGUMENT_TO_NON_NULL_TYPE:
problemMessage: "'{0}' shouldn't be called with a null argument for the non-nullable type argument '{1}'."
correctionMessage: Try adding a non-null argument.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the method being invoked
1: the type argument associated with the method
documentation: |-
#### Description
The analyzer produces this diagnostic when `null` is passed to either the
constructor `Future.value` or the method `Completer.complete` when the type
argument used to create the instance was non-nullable. Even though the type
system can't express this restriction, passing in a `null` results in a
runtime exception.
#### Example
The following code produces this diagnostic because `null` is being passed
to the constructor `Future.value` even though the type argument is the
non-nullable type `String`:
```dart
Future<String> f() {
return Future.value([!null!]);
}
```
#### Common fixes
Pass in a non-null value:
```dart
Future<String> f() {
return Future.value('');
}
```
NULL_AWARE_BEFORE_OPERATOR:
problemMessage: "The left operand uses '?.', so its value can be null."
comment: |-
When the left operand of a binary expression uses '?.' operator, it can be
`null`.
NULL_AWARE_IN_CONDITION:
problemMessage: "The value of the '?.' operator can be 'null', which isn't appropriate in a condition."
correctionMessage: "Try replacing the '?.' with a '.', testing the left-hand side for null if necessary."
comment: |-
A condition in a control flow statement could evaluate to `null` because it
uses the null-aware '?.' operator.
NULL_AWARE_IN_LOGICAL_OPERATOR:
problemMessage: "The value of the '?.' operator can be 'null', which isn't appropriate as an operand of a logical operator."
comment: |-
A condition in operands of a logical operator could evaluate to `null`
because it uses the null-aware '?.' operator.
NULL_CHECK_ALWAYS_FAILS:
problemMessage: "This null-check will always throw an exception because the expression will always evaluate to 'null'."
comment: |-
No parameters.
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when the null check operator (`!`)
is used on an expression whose value can only be `null`. In such a case
the operator always throws an exception, which likely isn't the intended
behavior.
#### Example
The following code produces this diagnostic because the function `g` will
always return `null`, which means that the null check in `f` will always
throw:
```dart
void f() {
[!g()!!];
}
Null g() => null;
```
#### Common fixes
If you intend to always throw an exception, then replace the null check
with an explicit `throw` expression to make the intent more clear:
```dart
void f() {
g();
throw TypeError();
}
Null g() => null;
```
OVERRIDE_ON_NON_OVERRIDING_FIELD:
sharedName: OVERRIDE_ON_NON_OVERRIDING_MEMBER
problemMessage: "The field doesn't override an inherited getter or setter."
correctionMessage: Try updating this class to match the superclass, or removing the override annotation.
hasPublishedDocs: true
comment: |-
A field with the override annotation does not override a getter or setter.
No parameters.
OVERRIDE_ON_NON_OVERRIDING_GETTER:
sharedName: OVERRIDE_ON_NON_OVERRIDING_MEMBER
problemMessage: "The getter doesn't override an inherited getter."
correctionMessage: Try updating this class to match the superclass, or removing the override annotation.
hasPublishedDocs: true
comment: |-
A getter with the override annotation does not override an existing getter.
No parameters.
OVERRIDE_ON_NON_OVERRIDING_METHOD:
sharedName: OVERRIDE_ON_NON_OVERRIDING_MEMBER
problemMessage: "The method doesn't override an inherited method."
correctionMessage: Try updating this class to match the superclass, or removing the override annotation.
hasPublishedDocs: true
comment: |-
A method with the override annotation does not override an existing method.
No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a class member is annotated with
the `@override` annotation, but the member isn't declared in any of the
supertypes of the class.
#### Example
The following code produces this diagnostic because `m` isn't declared in
any of the supertypes of `C`:
```dart
class C {
@override
String [!m!]() => '';
}
```
#### Common fixes
If the member is intended to override a member with a different name, then
update the member to have the same name:
```dart
class C {
@override
String toString() => '';
}
```
If the member is intended to override a member that was removed from the
superclass, then consider removing the member from the subclass.
If the member can't be removed, then remove the annotation.
OVERRIDE_ON_NON_OVERRIDING_SETTER:
sharedName: OVERRIDE_ON_NON_OVERRIDING_MEMBER
problemMessage: "The setter doesn't override an inherited setter."
correctionMessage: Try updating this class to match the superclass, or removing the override annotation.
hasPublishedDocs: true
comment: |-
A setter with the override annotation does not override an existing setter.
No parameters.
PATTERN_NEVER_MATCHES_VALUE_TYPE:
problemMessage: "The matched value type '{0}' can never match the required type '{1}'."
correctionMessage: "Try using a different pattern."
comment: |-
Parameters:
0: the matched value type
1: the required pattern type
RECEIVER_OF_TYPE_NEVER:
problemMessage: "The receiver is of type 'Never', and will never complete with a value."
correctionMessage: Try checking for throw expressions or type errors in the receiver
comment: |-
It is not an error to call or tear-off a method, setter, or getter, or to
read or write a field, on a receiver of static type `Never`.
Implementations that provide feedback about dead or unreachable code are
encouraged to indicate that any arguments to the invocation are
unreachable.
It is not an error to apply an expression of type `Never` in the function
position of a function call. Implementations that provide feedback about
dead or unreachable code are encouraged to indicate that any arguments to
the call are unreachable.
Parameters: none
RECORD_LITERAL_ONE_POSITIONAL_NO_TRAILING_COMMA:
problemMessage: "A record literal with exactly one positional field requires a trailing comma."
correctionMessage: Try adding a trailing comma.
hasPublishedDocs: true
REMOVED_LINT_USE:
problemMessage: "'{0}' was removed in Dart '{1}'"
correctionMessage: "Remove the reference to '{0}'."
comment: |-
An error code indicating use of a removed lint rule.
Parameters:
0: the rule name
1: the SDK version in which the lint was removed
REPLACED_LINT_USE:
problemMessage: "'{0}' was replaced by '{2}' in Dart '{1}'."
correctionMessage: "Replace '{0}' with '{1}'."
comment: |-
An error code indicating use of a removed lint rule.
Parameters:
0: the rule name
1: the SDK version in which the lint was removed
2: the name of a replacing lint
RETURN_OF_DO_NOT_STORE:
problemMessage: "'{0}' is annotated with 'doNotStore' and shouldn't be returned unless '{1}' is also annotated."
correctionMessage: "Annotate '{1}' with 'doNotStore'."
comment: |-
Parameters:
0: the name of the annotated function being invoked
1: the name of the function containing the return
hasPublishedDocs: true
documentation: |-
#### Description
The analyzer produces this diagnostic when a value that is annotated with
the [`doNotStore`][meta-doNotStore] annotation is returned from a method,
getter, or function that doesn't have the same annotation.
#### Example
The following code produces this diagnostic because the result of invoking
`f` shouldn't be stored, but the function `g` isn't annotated to preserve
that semantic:
```dart
import 'package:meta/meta.dart';
@doNotStore
int f() => 0;
int g() => [!f()!];
```
#### Common fixes
If the value that shouldn't be stored is the correct value to return, then
mark the function with the [`doNotStore`][meta-doNotStore] annotation:
```dart
import 'package:meta/meta.dart';
@doNotStore
int f() => 0;
@doNotStore
int g() => f();
```
Otherwise, return a different value from the function:
```dart
import 'package:meta/meta.dart';
@doNotStore
int f() => 0;
int g() => 0;
```
SDK_VERSION_ASYNC_EXPORTED_FROM_CORE:
removedIn: "3.2"
problemMessage: "The class '{0}' wasn't exported from 'dart:core' until version 2.1, but this code is required to be able to run on earlier versions."
correctionMessage: "Try either importing 'dart:async' or updating the SDK constraints."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the class
documentation: |-
#### Description
The analyzer produces this diagnostic when either the class `Future` or
`Stream` is referenced in a library that doesn't import `dart:async` in
code that has an SDK constraint whose lower bound is less than 2.1.0. In
earlier versions, these classes weren't defined in `dart:core`, so the
import was necessary.
#### Example
Here's an example of a pubspec that defines an SDK constraint with a lower
bound of less than 2.1.0:
```yaml
%uri="pubspec.yaml"
environment:
sdk: '>=2.0.0 <2.4.0'
```
In the package that has that pubspec, code like the following produces this
diagnostic:
```dart
void f([!Future!] f) {}
```
#### Common fixes
If you don't need to support older versions of the SDK, then you can
increase the SDK constraint to allow the classes to be referenced:
```yaml
environment:
sdk: '>=2.1.0 <2.4.0'
```
If you need to support older versions of the SDK, then import the
`dart:async` library.
```dart
import 'dart:async';
void f(Future f) {}
```
SDK_VERSION_AS_EXPRESSION_IN_CONST_CONTEXT:
removedIn: "3.2"
problemMessage: "The use of an as expression in a constant expression wasn't supported until version 2.3.2, but this code is required to be able to run on earlier versions."
correctionMessage: Try updating the SDK constraints.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when an `as` expression inside a
[constant context][] is found in code that has an SDK constraint whose
lower bound is less than 2.3.2. Using an `as` expression in a
[constant context][] wasn't supported in earlier versions, so this code
won't be able to run against earlier versions of the SDK.
#### Example
Here's an example of a pubspec that defines an SDK constraint with a lower
bound of less than 2.3.2:
```yaml
%uri="pubspec.yaml"
environment:
sdk: '>=2.1.0 <2.4.0'
```
In the package that has that pubspec, code like the following produces
this diagnostic:
```dart
const num n = 3;
const int i = [!n as int!];
```
#### Common fixes
If you don't need to support older versions of the SDK, then you can
increase the SDK constraint to allow the expression to be used:
```yaml
environment:
sdk: '>=2.3.2 <2.4.0'
```
If you need to support older versions of the SDK, then either rewrite the
code to not use an `as` expression, or change the code so that the `as`
expression isn't in a [constant context][]:
```dart
num x = 3;
int y = x as int;
```
SDK_VERSION_BOOL_OPERATOR_IN_CONST_CONTEXT:
removedIn: "3.2"
problemMessage: "The use of the operator '{0}' for 'bool' operands in a constant context wasn't supported until version 2.3.2, but this code is required to be able to run on earlier versions."
correctionMessage: Try updating the SDK constraints.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the operator
documentation: |-
#### Description
The analyzer produces this diagnostic when any use of the `&`, `|`, or `^`
operators on the class `bool` inside a [constant context][] is found in
code that has an SDK constraint whose lower bound is less than 2.3.2. Using
these operators in a [constant context][] wasn't supported in earlier
versions, so this code won't be able to run against earlier versions of the
SDK.
#### Example
Here's an example of a pubspec that defines an SDK constraint with a lower
bound of less than 2.3.2:
```yaml
%uri="pubspec.yaml"
environment:
sdk: '>=2.1.0 <2.4.0'
```
In the package that has that pubspec, code like the following produces this
diagnostic:
```dart
const bool a = true;
const bool b = false;
const bool c = a [!&!] b;
```
#### Common fixes
If you don't need to support older versions of the SDK, then you can
increase the SDK constraint to allow the operators to be used:
```yaml
environment:
sdk: '>=2.3.2 <2.4.0'
```
If you need to support older versions of the SDK, then either rewrite the
code to not use these operators, or change the code so that the expression
isn't in a [constant context][]:
```dart
const bool a = true;
const bool b = false;
bool c = a & b;
```
SDK_VERSION_CONSTRUCTOR_TEAROFFS:
problemMessage: "Tearing off a constructor requires the 'constructor-tearoffs' language feature."
correctionMessage: "Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'."
hasPublishedDocs: true
comment: |-
No parameters.
There is also a [ParserError.EXPERIMENT_NOT_ENABLED] code which catches
some cases of constructor tearoff features (like `List<int>.filled;`).
Other constructor tearoff cases are not realized until resolution
(like `List.filled;`).
documentation: |-
#### Description
The analyzer produces this diagnostic when a constructor tear-off is found
in code that has an SDK constraint whose lower bound is less than 2.15.
Constructor tear-offs weren't supported in earlier versions, so this code
won't be able to run against earlier versions of the SDK.
#### Example
Here's an example of a pubspec that defines an SDK constraint with a lower
bound of less than 2.15:
```yaml
%uri="pubspec.yaml"
environment:
sdk: '>=2.9.0 <2.15.0'
```
In the package that has that pubspec, code like the following produces this
diagnostic:
```dart
%language=2.14
var setConstructor = [!Set.identity!];
```
#### Common fixes
If you don't need to support older versions of the SDK, then you can
increase the SDK constraint to allow the operator to be used:
```yaml
environment:
sdk: '>=2.15.0 <2.16.0'
```
If you need to support older versions of the SDK, then rewrite the code to
not use constructor tear-offs:
```dart
%language=2.14
var setConstructor = () => Set.identity();
```
SDK_VERSION_EQ_EQ_OPERATOR_IN_CONST_CONTEXT:
removedIn: "3.2"
problemMessage: "Using the operator '==' for non-primitive types wasn't supported until version 2.3.2, but this code is required to be able to run on earlier versions."
correctionMessage: Try updating the SDK constraints.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the operator `==` is used on a
non-primitive type inside a [constant context][] is found in code that has
an SDK constraint whose lower bound is less than 2.3.2. Using this operator
in a [constant context][] wasn't supported in earlier versions, so this
code won't be able to run against earlier versions of the SDK.
#### Example
Here's an example of a pubspec that defines an SDK constraint with a lower
bound of less than 2.3.2:
```yaml
%uri="pubspec.yaml"
environment:
sdk: '>=2.1.0 <2.4.0'
```
In the package that has that pubspec, code like the following produces this
diagnostic:
```dart
%language=2.9
class C {}
const C a = null;
const C b = null;
const bool same = a [!==!] b;
```
#### Common fixes
If you don't need to support older versions of the SDK, then you can
increase the SDK constraint to allow the operator to be used:
```yaml
environment:
sdk: '>=2.3.2 <2.4.0'
```
If you need to support older versions of the SDK, then either rewrite the
code to not use the `==` operator, or change the code so that the
expression isn't in a [constant context][]:
```dart
%language=2.9
class C {}
const C a = null;
const C b = null;
bool same = a == b;
```
SDK_VERSION_EXTENSION_METHODS:
removedIn: "3.2"
problemMessage: "Extension methods weren't supported until version 2.6.0, but this code is required to be able to run on earlier versions."
correctionMessage: Try updating the SDK constraints.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when an extension declaration or an
extension override is found in code that has an SDK constraint whose lower
bound is less than 2.6.0. Using extensions wasn't supported in earlier
versions, so this code won't be able to run against earlier versions of the
SDK.
#### Example
Here's an example of a pubspec that defines an SDK constraint with a lower
bound of less than 2.6.0:
```yaml
%uri="pubspec.yaml"
environment:
sdk: '>=2.4.0 <2.7.0'
```
In the package that has that pubspec, code like the following produces
this diagnostic:
```dart
[!extension!] E on String {
void sayHello() {
print('Hello $this');
}
}
```
#### Common fixes
If you don't need to support older versions of the SDK, then you can
increase the SDK constraint to allow the syntax to be used:
```yaml
environment:
sdk: '>=2.6.0 <2.7.0'
```
If you need to support older versions of the SDK, then rewrite the code to
not make use of extensions. The most common way to do this is to rewrite
the members of the extension as top-level functions (or methods) that take
the value that would have been bound to `this` as a parameter:
```dart
void sayHello(String s) {
print('Hello $s');
}
```
SDK_VERSION_GT_GT_GT_OPERATOR:
problemMessage: "The operator '>>>' wasn't supported until version 2.14.0, but this code is required to be able to run on earlier versions."
correctionMessage: Try updating the SDK constraints.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the operator `>>>` is used in
code that has an SDK constraint whose lower bound is less than 2.14.0. This
operator wasn't supported in earlier versions, so this code won't be able
to run against earlier versions of the SDK.
#### Example
Here's an example of a pubspec that defines an SDK constraint with a lower
bound of less than 2.14.0:
```yaml
%uri="pubspec.yaml"
environment:
sdk: '>=2.0.0 <2.15.0'
```
In the package that has that pubspec, code like the following produces this
diagnostic:
```dart
int x = 3 [!>>>!] 4;
```
#### Common fixes
If you don't need to support older versions of the SDK, then you can
increase the SDK constraint to allow the operator to be used:
```yaml
environment:
sdk: '>=2.14.0 <2.15.0'
```
If you need to support older versions of the SDK, then rewrite the code to
not use the `>>>` operator:
```dart
int x = logicalShiftRight(3, 4);
int logicalShiftRight(int leftOperand, int rightOperand) {
int divisor = 1 << rightOperand;
if (divisor == 0) {
return 0;
}
return leftOperand ~/ divisor;
}
```
SDK_VERSION_IS_EXPRESSION_IN_CONST_CONTEXT:
removedIn: "3.2"
problemMessage: "The use of an is expression in a constant context wasn't supported until version 2.3.2, but this code is required to be able to run on earlier versions."
correctionMessage: Try updating the SDK constraints.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when an `is` expression inside a
[constant context][] is found in code that has an SDK constraint whose
lower bound is less than 2.3.2. Using an `is` expression in a
[constant context][] wasn't supported in earlier versions, so this code
won't be able to run against earlier versions of the SDK.
#### Example
Here's an example of a pubspec that defines an SDK constraint with a lower
bound of less than 2.3.2:
```yaml
%uri="pubspec.yaml"
environment:
sdk: '>=2.1.0 <2.4.0'
```
In the package that has that pubspec, code like the following produces
this diagnostic:
```dart
const Object x = 4;
const y = [!x is int!] ? 0 : 1;
```
#### Common fixes
If you don't need to support older versions of the SDK, then you can
increase the SDK constraint to allow the expression to be used:
```yaml
environment:
sdk: '>=2.3.2 <2.4.0'
```
If you need to support older versions of the SDK, then either rewrite the
code to not use the `is` operator, or, if that isn't possible, change the
code so that the `is` expression isn't in a
[constant context][]:
```dart
const Object x = 4;
var y = x is int ? 0 : 1;
```
SDK_VERSION_NEVER:
problemMessage: "The type 'Never' wasn't supported until version 2.12.0, but this code is required to be able to run on earlier versions."
correctionMessage: Try updating the SDK constraints.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a reference to the class `Never`
is found in code that has an SDK constraint whose lower bound is less than
2.12.0. This class wasn't defined in earlier versions, so this code won't
be able to run against earlier versions of the SDK.
#### Example
Here's an example of a pubspec that defines an SDK constraint with a lower
bound of less than 2.12.0:
```yaml
%uri="pubspec.yaml"
environment:
sdk: '>=2.5.0 <2.6.0'
```
In the package that has that pubspec, code like the following produces this
diagnostic:
```dart
%language=2.9
[!Never!] n;
```
#### Common fixes
If you don't need to support older versions of the SDK, then you can
increase the SDK constraint to allow the type to be used:
```yaml
environment:
sdk: '>=2.12.0 <2.13.0'
```
If you need to support older versions of the SDK, then rewrite the code to
not reference this class:
```dart
dynamic x;
```
SDK_VERSION_SET_LITERAL:
removedIn: "3.2"
problemMessage: "Set literals weren't supported until version 2.2, but this code is required to be able to run on earlier versions."
correctionMessage: Try updating the SDK constraints.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a set literal is found in code
that has an SDK constraint whose lower bound is less than 2.2.0. Set
literals weren't supported in earlier versions, so this code won't be able
to run against earlier versions of the SDK.
#### Example
Here's an example of a pubspec that defines an SDK constraint with a lower
bound of less than 2.2.0:
```yaml
%uri="pubspec.yaml"
environment:
sdk: '>=2.1.0 <2.4.0'
```
In the package that has that pubspec, code like the following produces this
diagnostic:
```dart
var s = [!<int>{}!];
```
#### Common fixes
If you don't need to support older versions of the SDK, then you can
increase the SDK constraint to allow the syntax to be used:
```yaml
environment:
sdk: '>=2.2.0 <2.4.0'
```
If you do need to support older versions of the SDK, then replace the set
literal with code that creates the set without the use of a literal:
```dart
var s = new Set<int>();
```
SDK_VERSION_SINCE:
problemMessage: "This API is available since SDK {0}, but constraints '{1}' don't guarantee it."
correctionMessage: Try updating the SDK constraints.
comment: |-
Parameters:
0: the version specified in the `@Since()` annotation
1: the SDK version constraints
SDK_VERSION_UI_AS_CODE:
removedIn: "3.2"
problemMessage: "The for, if, and spread elements weren't supported until version 2.3.0, but this code is required to be able to run on earlier versions."
correctionMessage: Try updating the SDK constraints.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a for, if, or spread element is
found in code that has an SDK constraint whose lower bound is less than
2.3.0. Using a for, if, or spread element wasn't supported in earlier
versions, so this code won't be able to run against earlier versions of the
SDK.
#### Example
Here's an example of a pubspec that defines an SDK constraint with a lower
bound of less than 2.3.0:
```yaml
%uri="pubspec.yaml"
environment:
sdk: '>=2.2.0 <2.4.0'
```
In the package that has that pubspec, code like the following produces
this diagnostic:
```dart
var digits = [[!for (int i = 0; i < 10; i++) i!]];
```
#### Common fixes
If you don't need to support older versions of the SDK, then you can
increase the SDK constraint to allow the syntax to be used:
```yaml
environment:
sdk: '>=2.3.0 <2.4.0'
```
If you need to support older versions of the SDK, then rewrite the code to
not make use of those elements:
```dart
var digits = _initializeDigits();
List<int> _initializeDigits() {
var digits = <int>[];
for (int i = 0; i < 10; i++) {
digits.add(i);
}
return digits;
}
```
SDK_VERSION_UI_AS_CODE_IN_CONST_CONTEXT:
removedIn: "3.2"
problemMessage: "The if and spread elements weren't supported in constant expressions until version 2.5.0, but this code is required to be able to run on earlier versions."
correctionMessage: Try updating the SDK constraints.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when an if or spread element inside
a [constant context][] is found in code that has an SDK constraint whose
lower bound is less than 2.5.0. Using an if or spread element inside a
[constant context][] wasn't supported in earlier versions, so this code
won't be able to run against earlier versions of the SDK.
#### Example
Here's an example of a pubspec that defines an SDK constraint with a lower
bound of less than 2.5.0:
```yaml
%uri="pubspec.yaml"
environment:
sdk: '>=2.4.0 <2.6.0'
```
In the package that has that pubspec, code like the following produces
this diagnostic:
```dart
const a = [1, 2];
const b = [[!...a!]];
```
#### Common fixes
If you don't need to support older versions of the SDK, then you can
increase the SDK constraint to allow the syntax to be used:
```yaml
environment:
sdk: '>=2.5.0 <2.6.0'
```
If you need to support older versions of the SDK, then rewrite the code to
not make use of those elements:
```dart
const a = [1, 2];
const b = [1, 2];
```
If that isn't possible, change the code so that the element isn't in a
[constant context][]:
```dart
const a = [1, 2];
var b = [...a];
```
STRICT_RAW_TYPE:
problemMessage: "The generic type '{0}' should have explicit type arguments but doesn't."
correctionMessage: "Use explicit type arguments for '{0}'."
comment: |-
When "strict-raw-types" is enabled, "raw types" must have type arguments.
A "raw type" is a type name that does not use inference to fill in missing
type arguments; instead, each type argument is instantiated to its bound.
Parameters:
0: the name of the generic type
SUBTYPE_OF_SEALED_CLASS:
problemMessage: "The class '{0}' shouldn't be extended, mixed in, or implemented because it's sealed."
correctionMessage: "Try composing instead of inheriting, or refer to the documentation of '{0}' for more information."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the sealed class
documentation: |-
#### Description
The analyzer produces this diagnostic when a sealed class (one that either
has the [`sealed`][meta-sealed] annotation or inherits or mixes in a
sealed class) is referenced in either the `extends`, `implements`, or
`with` clause of a class or mixin declaration if the declaration isn't in
the same package as the sealed class.
#### Example
Given a library in a package other than the package being analyzed that
contains the following:
```dart
%uri="package:a/a.dart"
import 'package:meta/meta.dart';
class A {}
@sealed
class B {}
```
The following code produces this diagnostic because `C`, which isn't in the
same package as `B`, is extending the sealed class `B`:
```dart
import 'package:a/a.dart';
[!class C extends B {}!]
```
#### Common fixes
If the class doesn't need to be a subtype of the sealed class, then change
the declaration so that it isn't:
```dart
import 'package:a/a.dart';
class B extends A {}
```
If the class needs to be a subtype of the sealed class, then either change
the sealed class so that it's no longer sealed or move the subclass into
the same package as the sealed class.
TEXT_DIRECTION_CODE_POINT_IN_COMMENT:
problemMessage: The Unicode code point 'U+{0}' changes the appearance of text from how it's interpreted by the compiler.
correctionMessage: Try removing the code point or using the Unicode escape sequence '\u{0}'.
hasPublishedDocs: true
comment: |-
Parameters:
0: the unicode sequence of the code point.
documentation: |-
#### Description
The analyzer produces this diagnostic when it encounters source that
contains text direction Unicode code points. These code points cause
source code in either a string literal or a comment to be interpreted
and compiled differently than how it appears in editors, leading to
possible security vulnerabilities.
#### Example
The following code produces this diagnostic twice because there are
hidden characters at the start and end of the label string:
```dart
var label = '[!I!]nteractive text[!'!];
```
#### Common fixes
If the code points are intended to be included in the string literal,
then escape them:
```dart
var label = '\u202AInteractive text\u202C';
```
If the code points aren't intended to be included in the string literal,
then remove them:
```dart
var label = 'Interactive text';
```
TEXT_DIRECTION_CODE_POINT_IN_LITERAL:
problemMessage: The Unicode code point 'U+{0}' changes the appearance of text from how it's interpreted by the compiler.
correctionMessage: Try removing the code point or using the Unicode escape sequence '\u{0}'.
hasPublishedDocs: true
comment: |-
Parameters:
0: the unicode sequence of the code point.
documentation: |-
#### Description
The analyzer produces this diagnostic when it encounters source that
contains text direction Unicode code points. These code points cause
source code in either a string literal or a comment to be interpreted
and compiled differently than how it appears in editors, leading to
possible security vulnerabilities.
#### Example
The following code produces this diagnostic twice because there are
hidden characters at the start and end of the label string:
```dart
var label = '[!I!]nteractive text[!'!];
```
#### Common fixes
If the code points are intended to be included in the string literal,
then escape them:
```dart
var label = '\u202AInteractive text\u202C';
```
If the code points aren't intended to be included in the string literal,
then remove them:
```dart
var label = 'Interactive text';
```
TYPE_CHECK_IS_NOT_NULL:
sharedName: TYPE_CHECK_WITH_NULL
problemMessage: "Tests for non-null should be done with '!= null'."
correctionMessage: "Try replacing the 'is! Null' check with '!= null'."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when there's a type check (using the
`as` operator) where the type is `Null`. There's only one value whose type
is `Null`, so the code is both more readable and more performant when it
tests for `null` explicitly.
#### Examples
The following code produces this diagnostic because the code is testing to
see whether the value of `s` is `null` by using a type check:
```dart
void f(String? s) {
if ([!s is Null!]) {
return;
}
print(s);
}
```
The following code produces this diagnostic because the code is testing to
see whether the value of `s` is something other than `null` by using a type
check:
```dart
void f(String? s) {
if ([!s is! Null!]) {
print(s);
}
}
```
#### Common fixes
Replace the type check with the equivalent comparison with `null`:
```dart
void f(String? s) {
if (s == null) {
return;
}
print(s);
}
```
TYPE_CHECK_IS_NULL:
sharedName: TYPE_CHECK_WITH_NULL
problemMessage: "Tests for null should be done with '== null'."
correctionMessage: "Try replacing the 'is Null' check with '== null'."
hasPublishedDocs: true
comment: No parameters.
UNDEFINED_HIDDEN_NAME:
problemMessage: "The library '{0}' doesn't export a member with the hidden name '{1}'."
correctionMessage: Try removing the name from the list of hidden members.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the library being imported
1: the name in the hide clause that isn't defined in the library
documentation: |-
#### Description
The analyzer produces this diagnostic when a hide combinator includes a
name that isn't defined by the library being imported.
#### Example
The following code produces this diagnostic because `dart:math` doesn't
define the name `String`:
```dart
import 'dart:math' hide [!String!], max;
var x = min(0, 1);
```
#### Common fixes
If a different name should be hidden, then correct the name. Otherwise,
remove the name from the list:
```dart
import 'dart:math' hide max;
var x = min(0, 1);
```
UNDEFINED_REFERENCED_PARAMETER:
problemMessage: "The parameter '{0}' isn't defined by '{1}'."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the undefined parameter
1: the name of the targeted member
documentation: |-
#### Description
The analyzer produces this diagnostic when an annotation of the form
[`UseResult.unless(parameterDefined: parameterName)`][meta-UseResult]
specifies a parameter name that isn't defined by the annotated function.
#### Example
The following code produces this diagnostic because the function `f`
doesn't have a parameter named `b`:
```dart
import 'package:meta/meta.dart';
@UseResult.unless(parameterDefined: [!'b'!])
int f([int? a]) => a ?? 0;
```
#### Common fixes
Change the argument named `parameterDefined` to match the name of one of
the parameters to the function:
```dart
import 'package:meta/meta.dart';
@UseResult.unless(parameterDefined: 'a')
int f([int? a]) => a ?? 0;
```
UNDEFINED_SHOWN_NAME:
problemMessage: "The library '{0}' doesn't export a member with the shown name '{1}'."
correctionMessage: Try removing the name from the list of shown members.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the library being imported
1: the name in the show clause that isn't defined in the library
documentation: |-
#### Description
The analyzer produces this diagnostic when a show combinator includes a
name that isn't defined by the library being imported.
#### Example
The following code produces this diagnostic because `dart:math` doesn't
define the name `String`:
```dart
import 'dart:math' show min, [!String!];
var x = min(0, 1);
```
#### Common fixes
If a different name should be shown, then correct the name. Otherwise,
remove the name from the list:
```dart
import 'dart:math' show min;
var x = min(0, 1);
```
UNNECESSARY_CAST:
aliasFor: HintCode.UNNECESSARY_CAST
comment: This is the new replacement for [HintCode.UNNECESSARY_CAST].
UNNECESSARY_CAST_PATTERN:
problemMessage: Unnecessary cast pattern.
correctionMessage: Try removing the cast pattern.
comment: No parameters.
UNNECESSARY_FINAL:
problemMessage: The keyword 'final' isn't necessary because the parameter is implicitly 'final'.
correctionMessage: Try removing the 'final'.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when either a field initializing
parameter or a super parameter in a constructor has the keyword `final`.
In both cases the keyword is unnecessary because the parameter is
implicitly `final`.
#### Examples
The following code produces this diagnostic because the field initializing
parameter has the keyword `final`:
```dart
class A {
int value;
A([!final!] this.value);
}
```
The following code produces this diagnostic because the super parameter in
`B` has the keyword `final`:
```dart
class A {
A(int value);
}
class B extends A {
B([!final!] super.value);
}
```
#### Common fixes
Remove the unnecessary `final` keyword:
```dart
class A {
A(int value);
}
class B extends A {
B(super.value);
}
```
UNNECESSARY_IGNORE:
problemMessage: "The diagnostic '{0}' isn't produced at this location so it doesn't need to be ignored."
correctionMessage: Try removing the name from the list, or removing the whole comment if this is the only name in the list.
comment: |-
Parameters:
0: the name of the diagnostic being ignored
UNNECESSARY_NAN_COMPARISON_FALSE:
sharedName: UNNECESSARY_NAN_COMPARISON
problemMessage: A double can't equal 'double.nan', so the condition is always 'false'.
correctionMessage: Try using 'double.isNan', or removing the condition.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a value is compared to
`double.nan` using either `==` or `!=`.
Dart follows the [IEEE 754] floating-point standard for the semantics of
floating point operations, which states that, for any floating point value
`x` (including NaN, positive infinity, and negative infinity),
- `NaN == x` is always false
- `NaN != x` is always true
As a result, comparing any value to NaN is pointless because the result is
already known (based on the comparison operator being used).
#### Example
The following code produces this diagnostic because `d` is being compared
to `double.nan`:
```dart
bool isNaN(double d) => d [!== double.nan!];
```
#### Common fixes
Use the getter `double.isNaN` instead:
```dart
bool isNaN(double d) => d.isNaN;
```
UNNECESSARY_NAN_COMPARISON_TRUE:
sharedName: UNNECESSARY_NAN_COMPARISON
problemMessage: A double can't equal 'double.nan', so the condition is always 'true'.
correctionMessage: Try using 'double.isNan', or removing the condition.
hasPublishedDocs: true
comment: No parameters.
UNNECESSARY_NO_SUCH_METHOD:
problemMessage: "Unnecessary 'noSuchMethod' declaration."
correctionMessage: "Try removing the declaration of 'noSuchMethod'."
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when there's a declaration of
`noSuchMethod`, the only thing the declaration does is invoke the
overridden declaration, and the overridden declaration isn't the
declaration in `Object`.
Overriding the implementation of `Object`'s `noSuchMethod` (no matter what
the implementation does) signals to the analyzer that it shouldn't flag any
inherited abstract methods that aren't implemented in that class. This
works even if the overriding implementation is inherited from a superclass,
so there's no value to declare it again in a subclass.
#### Example
The following code produces this diagnostic because the declaration of
`noSuchMethod` in `A` makes the declaration of `noSuchMethod` in `B`
unnecessary:
```dart
class A {
@override
dynamic noSuchMethod(x) => super.noSuchMethod(x);
}
class B extends A {
@override
dynamic [!noSuchMethod!](y) {
return super.noSuchMethod(y);
}
}
```
#### Common fixes
Remove the unnecessary declaration:
```dart
class A {
@override
dynamic noSuchMethod(x) => super.noSuchMethod(x);
}
class B extends A {}
```
UNNECESSARY_NULL_COMPARISON_FALSE:
sharedName: UNNECESSARY_NULL_COMPARISON
problemMessage: "The operand can't be null, so the condition is always 'false'."
correctionMessage: Try removing the condition, an enclosing condition, or the whole conditional statement.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when it finds an equality comparison
(either `==` or `!=`) with one operand of `null` and the other operand
can't be `null`. Such comparisons are always either `true` or `false`, so
they serve no purpose.
#### Examples
The following code produces this diagnostic because `x` can never be
`null`, so the comparison always evaluates to `true`:
```dart
void f(int x) {
if (x [!!= null!]) {
print(x);
}
}
```
The following code produces this diagnostic because `x` can never be
`null`, so the comparison always evaluates to `false`:
```dart
void f(int x) {
if (x [!== null!]) {
throw ArgumentError("x can't be null");
}
}
```
#### Common fixes
If the other operand should be able to be `null`, then change the type of
the operand:
```dart
void f(int? x) {
if (x != null) {
print(x);
}
}
```
If the other operand really can't be `null`, then remove the condition:
```dart
void f(int x) {
print(x);
}
```
UNNECESSARY_NULL_COMPARISON_TRUE:
sharedName: UNNECESSARY_NULL_COMPARISON
problemMessage: "The operand can't be null, so the condition is always 'true'."
correctionMessage: Remove the condition.
hasPublishedDocs: true
comment: No parameters.
UNNECESSARY_QUESTION_MARK:
problemMessage: "The '?' is unnecessary because '{0}' is nullable without it."
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the type
documentation: |-
#### Description
The analyzer produces this diagnostic when either the type `dynamic` or the
type `Null` is followed by a question mark. Both of these types are
inherently nullable so the question mark doesn't change the semantics.
#### Example
The following code produces this diagnostic because the question mark
following `dynamic` isn't necessary:
```dart
dynamic[!?!] x;
```
#### Common fixes
Remove the unneeded question mark:
```dart
dynamic x;
```
UNNECESSARY_SET_LITERAL:
problemMessage: Braces unnecessarily wrap this expression in a set literal.
correctionMessage: Try removing the set literal around the expression.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when a function that has a return
type of `void`, `Future<void>`, or `FutureOr<void>` uses an expression
function body (`=>`) and the returned value is a literal set containing a
single element.
Although the language allows it, returning a value from a `void` function
isn't useful because it can't be used at the call site. In this particular
case the return is often due to a misunderstanding about the syntax. The
braces aren't necessary and can be removed.
#### Example
The following code produces this diagnostic because the closure being
passed to `g` has a return type of `void`, but is returning a set:
```dart
void f() {
g(() => [!{1}!]);
}
void g(void Function() p) {}
```
#### Common fixes
Remove the braces from around the value:
```dart
void f() {
g(() => 1);
}
void g(void Function() p) {}
```
UNNECESSARY_TYPE_CHECK_FALSE:
sharedName: UNNECESSARY_TYPE_CHECK
problemMessage: "Unnecessary type check; the result is always 'false'."
correctionMessage: Try correcting the type check, or removing the type check.
hasPublishedDocs: true
comment: No parameters.
documentation: |-
#### Description
The analyzer produces this diagnostic when the value of a type check (using
either `is` or `is!`) is known at compile time.
#### Example
The following code produces this diagnostic because the test `a is Object?`
is always `true`:
```dart
bool f<T>(T a) => [!a is Object?!];
```
#### Common fixes
If the type check doesn't check what you intended to check, then change the
test:
```dart
bool f<T>(T a) => a is Object;
```
If the type check does check what you intended to check, then replace the
type check with its known value or completely remove it:
```dart
bool f<T>(T a) => true;
```
UNNECESSARY_TYPE_CHECK_TRUE:
sharedName: UNNECESSARY_TYPE_CHECK
problemMessage: "Unnecessary type check; the result is always 'true'."
correctionMessage: Try correcting the type check, or removing the type check.
hasPublishedDocs: true
comment: No parameters.
UNNECESSARY_WILDCARD_PATTERN:
problemMessage: Unnecessary wildcard pattern.
correctionMessage: Try removing the wildcard pattern.
comment: No parameters.
UNREACHABLE_SWITCH_CASE:
aliasFor: HintCode.UNREACHABLE_SWITCH_CASE
comment: This is the new replacement for [HintCode.UNREACHABLE_SWITCH_CASE].
UNUSED_CATCH_CLAUSE:
problemMessage: "The exception variable '{0}' isn't used, so the 'catch' clause can be removed."
correctionMessage: Try removing the catch clause.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the exception variable
documentation: |-
#### Description
The analyzer produces this diagnostic when a `catch` clause is found, and
neither the exception parameter nor the optional stack trace parameter are
used in the `catch` block.
#### Example
The following code produces this diagnostic because `e` isn't referenced:
```dart
void f() {
try {
int.parse(';');
} on FormatException catch ([!e!]) {
// ignored
}
}
```
#### Common fixes
Remove the unused `catch` clause:
```dart
void f() {
try {
int.parse(';');
} on FormatException {
// ignored
}
}
```
UNUSED_CATCH_STACK:
problemMessage: "The stack trace variable '{0}' isn't used and can be removed."
correctionMessage: Try removing the stack trace variable, or using it.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the stack trace variable
documentation: |-
#### Description
The analyzer produces this diagnostic when the stack trace parameter in a
`catch` clause isn't referenced within the body of the `catch` block.
#### Example
The following code produces this diagnostic because `stackTrace` isn't
referenced:
```dart
void f() {
try {
// ...
} catch (exception, [!stackTrace!]) {
// ...
}
}
```
#### Common fixes
If you need to reference the stack trace parameter, then add a reference to
it. Otherwise, remove it:
```dart
void f() {
try {
// ...
} catch (exception) {
// ...
}
}
```
UNUSED_ELEMENT:
aliasFor: HintCode.UNUSED_ELEMENT
comment: This is the new replacement for [HintCode.UNUSED_ELEMENT].
UNUSED_ELEMENT_PARAMETER:
aliasFor: HintCode.UNUSED_ELEMENT_PARAMETER
comment: This is the new replacement for [HintCode.UNUSED_ELEMENT_PARAMETER].
UNUSED_FIELD:
problemMessage: "The value of the field '{0}' isn't used."
correctionMessage: Try removing the field, or using it.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the unused field
documentation: |-
#### Description
The analyzer produces this diagnostic when a private field is declared but
never read, even if it's written in one or more places.
#### Example
The following code produces this diagnostic because the field
`_originalValue` isn't read anywhere in the library:
```dart
class C {
final String [!_originalValue!];
final String _currentValue;
C(this._originalValue) : _currentValue = _originalValue;
String get value => _currentValue;
}
```
It might appear that the field `_originalValue` is being read in the
initializer (`_currentValue = _originalValue`), but that is actually a
reference to the parameter of the same name, not a reference to the field.
#### Common fixes
If the field isn't needed, then remove it.
If the field was intended to be used, then add the missing code.
UNUSED_IMPORT:
problemMessage: "Unused import: '{0}'."
correctionMessage: Try removing the import directive.
hasPublishedDocs: true
comment: |-
Parameters:
0: the content of the unused import's URI
documentation: |-
#### Description
The analyzer produces this diagnostic when an import isn't needed because
none of the names that are imported are referenced within the importing
library.
#### Example
The following code produces this diagnostic because nothing defined in
`dart:async` is referenced in the library:
```dart
import [!'dart:async'!];
void main() {}
```
#### Common fixes
If the import isn't needed, then remove it.
If some of the imported names are intended to be used, then add the missing
code.
UNUSED_LABEL:
problemMessage: "The label '{0}' isn't used."
correctionMessage: "Try removing the label, or using it in either a 'break' or 'continue' statement."
hasPublishedDocs: true
comment: |-
Parameters:
0: the label that isn't used
documentation: |-
#### Description
The analyzer produces this diagnostic when a label that isn't used is
found.
#### Example
The following code produces this diagnostic because the label `loop` isn't
referenced anywhere in the method:
```dart
void f(int limit) {
[!loop:!] for (int i = 0; i < limit; i++) {
print(i);
}
}
```
#### Common fixes
If the label isn't needed, then remove it:
```dart
void f(int limit) {
for (int i = 0; i < limit; i++) {
print(i);
}
}
```
If the label is needed, then use it:
```dart
void f(int limit) {
loop: for (int i = 0; i < limit; i++) {
print(i);
if (i != 0) {
break loop;
}
}
}
```
TODO(brianwilkerson) Highlight the identifier without the colon.
UNUSED_LOCAL_VARIABLE:
problemMessage: "The value of the local variable '{0}' isn't used."
correctionMessage: Try removing the variable or using it.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the unused variable
documentation: |-
#### Description
The analyzer produces this diagnostic when a local variable is declared but
never read, even if it's written in one or more places.
#### Example
The following code produces this diagnostic because the value of `count` is
never read:
```dart
void main() {
int [!count!] = 0;
}
```
#### Common fixes
If the variable isn't needed, then remove it.
If the variable was intended to be used, then add the missing code.
UNUSED_RESULT:
problemMessage: "The value of '{0}' should be used."
correctionMessage: Try using the result by invoking a member, passing it to a function, or returning it from this function.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name of the annotated method, property or function
documentation: |-
#### Description
The analyzer produces this diagnostic when a function annotated with
[`useResult`][meta-useResult] is invoked, and the value returned by that
function isn't used. The value is considered to be used if a member of the
value is invoked, if the value is passed to another function, or if the
value is assigned to a variable or field.
#### Example
The following code produces this diagnostic because the invocation of
`c.a()` isn't used, even though the method `a` is annotated with
[`useResult`][meta-useResult]:
```dart
import 'package:meta/meta.dart';
class C {
@useResult
int a() => 0;
int b() => 0;
}
void f(C c) {
c.[!a!]();
}
```
#### Common fixes
If you intended to invoke the annotated function, then use the value that
was returned:
```dart
import 'package:meta/meta.dart';
class C {
@useResult
int a() => 0;
int b() => 0;
}
void f(C c) {
print(c.a());
}
```
If you intended to invoke a different function, then correct the name of
the function being invoked:
```dart
import 'package:meta/meta.dart';
class C {
@useResult
int a() => 0;
int b() => 0;
}
void f(C c) {
c.b();
}
```
UNUSED_RESULT_WITH_MESSAGE:
sharedName: UNUSED_RESULT
problemMessage: "'{0}' should be used. {1}."
correctionMessage: Try using the result by invoking a member, passing it to a function, or returning it from this function.
hasPublishedDocs: true
comment: |-
The result of invoking a method, property, or function annotated with
`@useResult` must be used (assigned, passed to a function as an argument,
or returned by a function).
Parameters:
0: the name of the annotated method, property or function
1: message details
UNUSED_SHOWN_NAME:
problemMessage: "The name {0} is shown, but isn't used."
correctionMessage: Try removing the name from the list of shown members.
hasPublishedDocs: true
comment: |-
Parameters:
0: the name that is shown but not used
documentation: |-
#### Description
The analyzer produces this diagnostic when a show combinator includes a
name that isn't used within the library. Because it isn't referenced, the
name can be removed.
#### Example
The following code produces this diagnostic because the function `max`
isn't used:
```dart
import 'dart:math' show min, [!max!];
var x = min(0, 1);
```
#### Common fixes
Either use the name or remove it:
```dart
import 'dart:math' show min;
var x = min(0, 1);
```
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