Re-apply "Implement operator== and hashCode for bound closures."

tests/language/bound_closure_equality_test.dart

Index: tests/language/bound_closure_equality_test.dart
===================================================================
--- tests/language/bound_closure_equality_test.dart	(revision 0)
+++ tests/language/bound_closure_equality_test.dart	(revision 0)
@@ -0,0 +1,76 @@
+// Copyright (c) 2013, 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 {
+  const A();
+  foo() => 42;
+}
+
+class B {
+  foo() => 42;
+}
+
+main() {
+  // Use an array to defeat type inferencing.
+  var array = [new A(), new A(), new B(), new B()];
+  var set = new Set.from(array.map((a) => a.foo));
+  Expect.equals(array.length, set.length);
+  set.addAll(array.map((a) => a.foo));
+  Expect.equals(array.length, set.length);
+
+  for (int i = 0; i < array.length; i += 2) {
+    Expect.isTrue(set.contains(array[i].foo));
+    Expect.equals(array[i], array[i]);
+    Expect.equals(array[i].foo, array[i].foo);
+    Expect.equals(array[i].foo.hashCode, array[i].foo.hashCode);
+    for (int j = 0; j < array.length; j++) {
+      if (i == j) continue;
+      Expect.notEquals(array[i].foo, array[j].foo);
+    }
+  }
+
+  // Try with dart2js intercepted types.
+  array =  ['foo', 'bar', [], [], const []];
+  set = new Set.from(array.map((a) => a.indexOf));
+  Expect.equals(array.length, set.length);
+  set.addAll(array.map((a) => a.indexOf));
+  Expect.equals(array.length, set.length);
+
+  for (int i = 0; i < array.length; i += 2) {
+    Expect.isTrue(set.contains(array[i].indexOf));
+    Expect.equals(array[i], array[i]);
+    Expect.equals(array[i].indexOf, array[i].indexOf);
+    Expect.equals(array[i].indexOf.hashCode, array[i].indexOf.hashCode);
+    for (int j = 0; j < array.length; j++) {
+      if (i == j) continue;
+      Expect.notEquals(array[i].indexOf, array[j].indexOf);
+    }
+  }
+
+  array = [const A(), const A()];
+  set = new Set.from(array.map((a) => a.foo));
+  Expect.equals(1, set.length);
+  set.addAll(array.map((a) => a.foo));
+  Expect.equals(1, set.length);
+
+  Expect.isTrue(set.contains(array[0].foo));
+  Expect.equals(array[0].foo, array[0].foo);
+  Expect.equals(array[0].foo.hashCode, array[0].foo.hashCode);
+  Expect.equals(array[0].foo, array[1].foo);
+  Expect.equals(array[0].foo.hashCode, array[1].foo.hashCode);
+
+  array = [const [], const []];
+  set = new Set.from(array.map((a) => a.indexOf));
+  Expect.equals(1, set.length);
+  set.addAll(array.map((a) => a.indexOf));
+  Expect.equals(1, set.length);
+
+  Expect.isTrue(set.contains(array[0].indexOf));
+  Expect.equals(array[0].indexOf, array[0].indexOf);
+  Expect.equals(array[0].indexOf.hashCode, array[0].indexOf.hashCode);
+  Expect.equals(array[0].indexOf, array[1].indexOf);
+  Expect.equals(array[0].indexOf.hashCode, array[1].indexOf.hashCode);
+}