|  | // Copyright (c) 2016, 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. | 
|  |  | 
|  | // @dart = 2.9 | 
|  | import 'package:expect/expect.dart'; | 
|  |  | 
|  | class Implementation { | 
|  | dynamic method(int x) {} | 
|  | } | 
|  |  | 
|  | abstract class Interface<T> { | 
|  | dynamic method(T x); | 
|  | } | 
|  |  | 
|  | class Subclass extends Implementation implements Interface<int> {} | 
|  |  | 
|  | main() { | 
|  | Subclass subclass = new Subclass(); | 
|  | Interface<int> intInterface = subclass; | 
|  | Interface<num> numInterface = intInterface; | 
|  | Expect.throws(() => numInterface.method(2.5)); | 
|  | } |