anchor.diff:    }
   
     /// The code of the const-construction of this reflector.
  -  String _constConstructionCode(_ImportCollector importCollector) {
  +  Future<String> _constConstructionCode(
  +      _ImportCollector importCollector) async {
       String prefix = importCollector._getPrefix(_reflector.library);
       if (_isPrivateName(_reflector.name)) {
  -      _severe("Cannot access private name `${_reflector.name}`", _reflector);
  +      await _severe(
  +          "Cannot access private name `${_reflector.name}`", _reflector);
       }
       return "const $prefix${_reflector.name}()";
     }
  
positive.code:     NodeList<ConstructorInitializer> initializers =
          constructorDeclarationNode.initializers;
      if (initializers.length > 1) {
        constructorFail();
        return false;
      }
  
  
negative.code:         descriptor & constants.classTypeAttribute != 0);
    }
  
    Future<bool> _hasSupportedReflectedTypeArguments(DartType dartType) async {
      if (dartType is ParameterizedType) {
        for (DartType typeArgument in dartType.typeArguments) {
          if (!await _hasSupportedReflectedTypeArguments(typeArgument)) {
            return false;
          }
        }
        return true;
      } else if (dartType is TypeParameterType || dartType.isDynamic) {
        return false;
      } else {
        await _severe('`reflectedTypeArguments` where an actual type argument '
            '(possibly nested) is $dartType');
        return false;
      }
  