Implement MirrorUsed.targets for libraries

dart/tests/compiler/dart2js/mirrors_used_test.dart

Index: dart/tests/compiler/dart2js/mirrors_used_test.dart
diff --git a/dart/tests/compiler/dart2js/mirrors_used_test.dart b/dart/tests/compiler/dart2js/mirrors_used_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..09fdd29c9b883a28848d4f775b1914e9865e1c14
--- /dev/null
+++ b/dart/tests/compiler/dart2js/mirrors_used_test.dart
@@ -0,0 +1,95 @@
+// 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.
+
+/// Test that the @MirrorsUsed annotation suppress hints and that only
+/// requested elements are retained for reflection.
+library dart2js.test.mirrors_used_test;
+
+import 'package:expect/expect.dart';
+
+import 'memory_compiler.dart' show
+    compilerFor;
+
+import '../../../sdk/lib/_internal/compiler/implementation/apiimpl.dart' show
+    Compiler;
+
+import '../../../sdk/lib/_internal/compiler/implementation/dart2jslib.dart' show
+    SourceString;
+
+import
+    '../../../sdk/lib/_internal/compiler/implementation/elements/elements.dart'
+show
+    Elements;
+
+void expectOnlyVerboseInfo(Uri uri, int begin, int end, String message, kind) {
+  if (kind.name == 'verbose info') {
+    print(message);
+    return;
+  }
+  throw '$uri:$begin:$end: $kind: $message';
+}
+
+void main() {
+  Compiler compiler = compilerFor(
+      MEMORY_SOURCE_FILES, diagnosticHandler: expectOnlyVerboseInfo);
+  compiler.runCompiler(Uri.parse('memory:main.dart'));
+
+  print('');
+  List generatedCode =
+      Elements.sortedByPosition(compiler.enqueuer.codegen.generatedCode.keys);
+  for (var element in generatedCode) {
+    print(element);
+  }
+  print('');
+
+  // This assertion can fail for two reasons:
+  // 1. Too many elements retained for reflection.
+  // 2. Some code was refactored, and there are more methods.
+  // Either situation could be problematic, but in situation 2, it is often
+  // acceptable to increase [expectedMethodCount] a little.
+  int expectedMethodCount = 315;
+  Expect.isTrue(
+      generatedCode.length <= expectedMethodCount,
+      'Too many compiled methods: '
+      '${generatedCode.length} > $expectedMethodCount');
+
+  for (var library in compiler.libraries.values) {
+    library.forEachLocalMember((member) {
+      if (library == compiler.mainApp) {
+        // TODO(ahe): We currently retain the entire library. Update this test
+        // to test that only Foo is retained.
+        Expect.isTrue(
+            compiler.backend.isNeededForReflection(member), '$member');
+      } else {
+        Expect.isFalse(
+            compiler.backend.isNeededForReflection(member), '$member');
+      }
+    });
+  }
+}
+
+const MEMORY_SOURCE_FILES = const <String, String> {
+  'main.dart': """
+@MirrorsUsed(targets: const [Foo], override: '*')
+import 'dart:mirrors';
+
+import 'library.dart';
+
+class Foo {}
+
+main() {
+  useReflect(Foo);
+}
+""",
+  'library.dart': """
+library lib;
+
+import 'dart:mirrors';
+
+useReflect(type) {
+  print(new Symbol('Foo'));
+  print(MirrorSystem.getName(reflectClass(type).owner.qualifiedName));
+}
+""",
+};