| // Copyright (c) 2021, the Dart project authors. Please see the AUTHORS file | |
| // for details. All rights reserved. Use of this source code is governed by a | |
| // BSD-style license that can be found in the LICENSE file. | |
| import 'dart:async'; | |
| Future<int> foo<X extends Object?>(X x) async { | |
| if (x is Future<int>) { | |
| return x; | |
| } else { | |
| throw 42; | |
| } | |
| } | |
| main() {} |