dart-sdk/pkg/front_end/error_recovery.yaml

# Copyright (c) 2017, 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.

# Each entry in this file corresponds to an error recovery scenario. For each
# scenario we specify:
#
#  1. An explanation of the problem (description).
#  2. Important recovery notes (recovery): a list of text notes explaining of
#     how the code is interpreted by the front-end and its clients.
#  3. An optional set of questions if we don't have the answer at this
#     moment (questions).
#  4. An example code that illustrates the problem (example).
#
# At this time this is just a documentation file, the goal however is to turn it
# also into a test suite so every example can be tested automatically.
#
# To do so we can start annotating the examples to indicate relevant error
# locations with comments of the form `/*@error=name*/`, where `name` is a
# message name from `messages.yaml` that corresponds to the error (if known). If
# the compiler doesn't yet have a specific error message for the error, use
# `/*@error=?*/`. This comment should go immediately before the token where the
# error is reported. If we know at this time that the error has a region,
# include an /*@errorEnd*/ at the point where the region ends.

NameConflictDuplicateField:
  description: "A field was declared twice."
  recovery:
    - "both fields can be seen in the generated kernel output."
    - "code completion works on the types and inside initializers of either field."
    - "any errors from the usage of the field should be lower priority than this error."
    - "accesses to the field get resolved to the first declaration (in text order)."
  example: >-
    List bar = [1, 2];
    StringBuffer foo = new StringBuffer();
    class A {
      int    /*@error=DuplicatedName*/ field /*@errorEnd*/ = bar.length;
      String /*@error=DuplicatedName*/ field /*@errorEnd*/ = '$foo';
    }    

NameConflictDuplicateMethod:
  description: "A method was declared twice."
  recovery:
    - "both methods can be seen in the generated kernel output."
    - "code completion works within both methods."
    - "other code that accesses the method will be resolved to the first declaration."
  example: >-
    List bar = [1, 2];
    class A {
      int /*@error=DuplicatedName*/ m /*@errorEnd*/() => bar.length;
      int /*@error=DuplicatedName*/ m /*@errorEnd*/(StringBuffer foo) => '$foo';
    }    

NameConflictInconsistentMemberKind:
  description: "A method and a field have the same name."
  recovery:
    - "both can be seen in the generated output."
    - "first declaration wins."
  example: >-
    List bar = [1, 2];
    class A {
      int /*@error=DuplicatedName*/ m /*@errorEnd*/ = bar.length;
      int /*@error=DuplicatedName*/ m /*@errorEnd*/(StringBuffer foo) => '$foo';
    }    

ImportIsOutOfOrder:    
  description: "An import was written below a definition."
  recovery:
    - "treat it as if the import was on top."
    - "no cascading errors are presented as if the import was missing."
  example: >-
    class A extends B {}
    /*@error=?*/
    import 'b.dart'; // b.dart defines B
    /*@errorEnd*/    

CallAMissingConstructor:
  description: "A named constructor has a typo in the name."
  recovery:
    - "keep the expression where it occurs."
    - "treat the type of the expression as if a valid constructor was used."
  example: >-
    class C {
      bar() => null;
    }
    main() {
      var x = new C./*error=MethodNotFound*/foo();
      x.bar(); // no errors here, `x` has inferred type `C`.
    }    

TreatAbstractFunctionsAsEmpty:
  description: "A function in a non-abstract class is missing a body."
  recovery: "Treat it as if it was empty."
  example: >-
    class A {
      foo() /*@error=ExpectedBody*/;
    }    

IgnoreEmptyOptionalArgs:
  description: "A function declares optional argument, but the list is empty."
  recovery: "Treat it as if it wasn't there."
  example: >-
    m(a, b, []){}    

IgnoreEmptyOptionalArgs:
  description: "A function declares both positional and named arguments."
  questions: "Treat it as if only named arguments are there?"
  example: >-
    m(a, b, [c], {d}){}    

# TODO(sigmund): add details to the list below

NameConflictDuplicateTopLevelField:
  description: "A top-level field was declared twice."

NameConflictDuplicateTopLevelMethod:
  description: "A top-level method was declared twice."

NameConflictDuplicateTopLevelDeclaration:
  description: "Two top-level declarations use the same name."