anchor.diff:          messageOperatorWithTypeParameters,
           messagePositionalAfterNamedArgument,
           templateDuplicateLabelInSwitchStatement,
  -        templateExpectedButGot,
           templateExpectedIdentifier,
           templateExperimentNotEnabled,
           templateExtraneousModifier,
  -        templateInternalProblemUnhandled,
  -        templateUnexpectedToken;
  +        templateInternalProblemUnhandled;
   import 'package:_fe_analyzer_shared/src/parser/parser.dart'
       show
           Assert,
  
positive.code:   /// `true` if non-nullable behavior is enabled.
    final bool enableNonNullable;
  
    /// `true` if spread-collections behavior is enabled
    final bool enableSpreadCollections;
  
    /// `true` if control-flow-collections behavior is enabled
    final bool enableControlFlowCollections;
  
    /// `true` if triple-shift behavior is enabled
    final bool enableTripleShift;
  
  
negative.code:     // behavior and will be removed once unified collection has been enabled
      bool hasSetEntry,
    ) {
      List<CollectionElement> elements = popCollectionElements(count);
  
      var typeArguments = pop() as TypeArgumentList?;
      push(ast.setOrMapLiteral(
        constKeyword: constKeyword,
        typeArguments: typeArguments,
        leftBracket: leftBrace,
        elements: elements,
        rightBracket: rightBrace,
      ));
    }
  
    @override
  