anchor.diff:    @override
     void visitClassDeclaration(ClassDeclaration node) {
       Scope outerScope = nameScope;
  -    var outerClass = enclosingClass;
       try {
         ClassElement element = node.declaredElement!;
  -      enclosingClass = node.declaredElement;
         node.metadata.accept(this);
   
         nameScope = TypeParameterScope(
  
positive.code:   @override
    void visitMixinDeclaration(MixinDeclaration node) {
      Scope outerScope = nameScope;
      var outerClass = enclosingClass;
      try {
        ClassElement element = node.declaredElement!;
        enclosingClass = element;
        node.metadata.accept(this);
  
        nameScope = TypeParameterScope(nameScope, element.typeParameters);
  
negative.code: 
    @override
    void visitFunctionDeclaration(FunctionDeclaration node) {
      node.metadata.accept(this);
      Scope outerScope = nameScope;
      try {
  