Make USES_DYNAMIC_AS_BOTTOM (fuzzy arrows) a warning

Fixes https://github.com/dart-lang/sdk/issues/31874 .

Change-Id: I75b43f52692f5860d8c4e78acb15b9c9281754a5
Reviewed-on: https://dart-review.googlesource.com/34506
Commit-Queue: Leaf Petersen <leafp@google.com>
Reviewed-by: Jenny Messerly <jmesserly@google.com>

pkg/analyzer/lib/error/error.dart

@@ -299,7 +299,6 @@ const List<ErrorCode> errorCodeValues = const [
   HintCode.UNUSED_IMPORT,
   HintCode.UNUSED_LOCAL_VARIABLE,
   HintCode.UNUSED_SHOWN_NAME,
-  HintCode.USES_DYNAMIC_AS_BOTTOM,
   HintCode.USE_OF_VOID_RESULT,
   HintCode.WRONG_NUMBER_OF_TYPE_ARGUMENTS_METHOD,
   HtmlErrorCode.PARSE_ERROR,
@@ -669,6 +668,7 @@ const List<ErrorCode> errorCodeValues = const [
   StrongModeCode.TOP_LEVEL_INSTANCE_GETTER,
   StrongModeCode.TOP_LEVEL_TYPE_ARGUMENTS,
   StrongModeCode.TOP_LEVEL_UNSUPPORTED,
+  StrongModeCode.USES_DYNAMIC_AS_BOTTOM,
   TodoCode.TODO,
 ];
 

pkg/analyzer/lib/src/dart/error/hint_codes.dart

@@ -37,18 +37,6 @@ class HintCode extends ErrorCode {
       'ARGUMENT_TYPE_NOT_ASSIGNABLE',
       "The argument type '{0}' can't be assigned to the parameter type '{1}'.");
 
-  /**
-   * This hint is generated when a function type is assigned to a function
-   * typed location, and the assignment will be invalid after fuzzy arrows
-   * (the treatment of dynamic as bottom in certain locations) is removed.
-   *
-   */
-  static const HintCode USES_DYNAMIC_AS_BOTTOM = const HintCode(
-      'USES_DYNAMIC_AS_BOTTOM',
-      "A function of type '{0}' can't be assigned to a variable of type '{1}'.",
-      "Try changing the type of the function, or "
-      "casting the right-hand type to '{1}'.");
-
   /**
    * When the target expression uses '?.' operator, it can be `null`, so all the
    * subsequent invocations should also use '?.' operator.

pkg/analyzer/lib/src/error/codes.dart

@@ -5069,6 +5069,19 @@ class StrongModeCode extends ErrorCode {
       "The type of '{0}' can't be inferred because {1} expressions aren't supported.",
       "Try adding an explicit type for '{0}'.");
 
+  /**
+   * This warning is generated when a function type is assigned to a function
+   * typed location, and the assignment will be invalid after fuzzy arrows
+   * (the treatment of dynamic as bottom in certain locations) is removed.
+   *
+   */
+  static const StrongModeCode USES_DYNAMIC_AS_BOTTOM = const StrongModeCode(
+      ErrorType.STATIC_TYPE_WARNING,
+      'USES_DYNAMIC_AS_BOTTOM',
+      "A function of type '{0}' can't be assigned to a location of type '{1}'.",
+      "Try changing the parameter types of the function or of the "
+      " receiving location.");
+
   @override
   final ErrorType type;
 

pkg/analyzer/lib/src/task/strong/checker.dart

@@ -1123,7 +1123,7 @@ class CodeChecker extends RecursiveAstVisitor {
       var cTo = rules.typeToConcreteType(to);
       // If still true, no warning needed
       if (rules.isSubtypeOf(cFrom, cTo)) return;
-      _recordMessage(expr, HintCode.USES_DYNAMIC_AS_BOTTOM, [from, to]);
+      _recordMessage(expr, StrongModeCode.USES_DYNAMIC_AS_BOTTOM, [from, to]);
     }
   }
 
@@ -1276,9 +1276,7 @@ class CodeChecker extends RecursiveAstVisitor {
         errorCode.name.startsWith('STRONG_MODE_TOP_LEVEL_')) {
       severity = ErrorSeverity.ERROR;
     }
-    if (severity != ErrorSeverity.INFO ||
-        _options.strongModeHints ||
-        errorCode == HintCode.USES_DYNAMIC_AS_BOTTOM) {
+    if (severity != ErrorSeverity.INFO || _options.strongModeHints) {
       int begin = node is AnnotatedNode
           ? node.firstTokenAfterCommentAndMetadata.offset
           : node.offset;

pkg/analyzer/test/src/task/options_test.dart

@@ -270,6 +270,7 @@ class ErrorCodeValuesTest {
         removeCode(StrongModeCode.TOP_LEVEL_INSTANCE_GETTER);
         removeCode(StrongModeCode.TOP_LEVEL_TYPE_ARGUMENTS);
         removeCode(StrongModeCode.TOP_LEVEL_UNSUPPORTED);
+        removeCode(StrongModeCode.USES_DYNAMIC_AS_BOTTOM);
       } else if (errorType == TodoCode) {
         declaredNames.remove('TODO_REGEX');
       }

pkg/analyzer/test/src/task/strong/checker_test.dart

@@ -489,7 +489,7 @@ void main() {
   f1("hello");
   dynamic f2 = foo;
   (/*info:DYNAMIC_INVOKE*/f2("hello"));
-  DynFun f3 = /*info:USES_DYNAMIC_AS_BOTTOM*/foo;
+  DynFun f3 = /*warning:USES_DYNAMIC_AS_BOTTOM*/foo;
   (/*info:DYNAMIC_INVOKE*/f3("hello"));
   (/*info:DYNAMIC_INVOKE*/f3(42));
   StrFun f4 = foo;
@@ -673,7 +673,7 @@ void main() {
     /*info:DYNAMIC_INVOKE*/f./*error:UNDEFINED_METHOD*/col(3);
   }
   {
-    A f = /*info:USES_DYNAMIC_AS_BOTTOM*/new B();
+    A f = /*warning:USES_DYNAMIC_AS_BOTTOM*/new B();
     int x;
     double y;
     x = /*info:DYNAMIC_CAST, info:DYNAMIC_INVOKE*/f(3);
@@ -686,7 +686,7 @@ void main() {
     /*info:DYNAMIC_INVOKE*/g.col(42.0);
     /*info:DYNAMIC_INVOKE*/g.foo(42.0);
     /*info:DYNAMIC_INVOKE*/g.x;
-    A f = /*info:USES_DYNAMIC_AS_BOTTOM*/new B();
+    A f = /*warning:USES_DYNAMIC_AS_BOTTOM*/new B();
     /*info:DYNAMIC_INVOKE*/f./*error:UNDEFINED_METHOD*/col(42.0);
     /*info:DYNAMIC_INVOKE*/f./*error:UNDEFINED_METHOD*/foo(42.0);
     /*info:DYNAMIC_INVOKE*/f./*error:UNDEFINED_GETTER*/x;
@@ -3091,7 +3091,7 @@ void main() {
   TakesA<int> f;
   TakesA<dynamic> g;
   TakesA<String> h;
-  g = /*info:USES_DYNAMIC_AS_BOTTOM*/h;
+  g = /*warning:USES_DYNAMIC_AS_BOTTOM*/h;
   f = /*info:DOWN_CAST_COMPOSITE*/f ?? g;
 }
 ''');