anchor.diff:    @override
     void visitChildren(ElementVisitor visitor) {
       super.visitChildren(visitor);
  -    _safelyVisitPossibleChild(returnType, visitor);
       safelyVisitChildren(typeParameters, visitor);
       safelyVisitChildren(parameters, visitor);
     }
  
positive.code:     }
      return annotations;
    }
  
    /// If the given [type] is a generic function type, then the element
    /// associated with the type is implicitly a child of this element and should
    /// be visited by the given [visitor].
    void _safelyVisitPossibleChild(DartType? type, ElementVisitor visitor) {
      var element = type?.element;
      if (element is GenericFunctionTypeElementImpl &&
          element.enclosingElement is! FunctionTypeAliasElement) {
        element.accept(visitor);
      }
    }
  }
  
  /// Abstract base class for elements whose type is guaranteed to be a function
  
negative.code:   @override
    void visitChildren(ElementVisitor visitor) {
      super.visitChildren(visitor);
      safelyVisitChildren(typeParameters, visitor);
      safelyVisitChildren(parameters, visitor);
    }
  