|  | // Copyright (c) 2014, 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 "package:expect/expect.dart"; | 
|  |  | 
|  | class A { | 
|  | static const b = const B(); | 
|  | } | 
|  |  | 
|  | class B implements A { | 
|  | const B(); | 
|  |  | 
|  | operator ==(o) => true; // //# 00: compile-time error | 
|  | } | 
|  |  | 
|  | main() { | 
|  | // It is a compile-time error if the key type overrides operator ==. | 
|  | var m = const {A.b: 42}; | 
|  | Expect.equals(42, m[const B()]); | 
|  |  | 
|  | m = const {"foo": 99, A.b: 499}; | 
|  | Expect.equals(499, m[const B()]); | 
|  | } |