Implement MirrorUsed.targets for libraries

dart/sdk/lib/_internal/compiler/implementation/compiler.dart

Index: dart/sdk/lib/_internal/compiler/implementation/compiler.dart
diff --git a/dart/sdk/lib/_internal/compiler/implementation/compiler.dart b/dart/sdk/lib/_internal/compiler/implementation/compiler.dart
index 86f5db8a6694bea5537badd7cf79ad520b404139..b6c76067f9e7c04b180ebdcb5bf7cadc5931120b 100644
--- a/dart/sdk/lib/_internal/compiler/implementation/compiler.dart
+++ b/dart/sdk/lib/_internal/compiler/implementation/compiler.dart
@@ -211,6 +211,12 @@ abstract class Backend {
   void registerMetadataInstantiatedType(DartType type, TreeElements elements) {}
   void registerMetadataStaticUse(Element element) {}
   void registerMetadataGetOfStaticFunction(FunctionElement element) {}
+
+  void registerMirrorUsage(Set<String> symbols,

[Johnni Winther, 2013/07/30 11:15:09]

Please document.

[ahe, 2013/07/30 12:05:45]

Done.

+                           Set<Element> targets,
+                           Set<Element> metaTargets) {}
+
+  bool isNeededForReflection(Element element) => false;

[Johnni Winther, 2013/07/30 11:15:09]

Please document. For instance, is [element] only needed for reflection?

[ahe, 2013/07/30 12:05:45]

Done.

 }
 
 /**
@@ -338,6 +344,9 @@ abstract class Compiler implements DiagnosticListener {
   LibraryElement foreignLibrary;
   LibraryElement mainApp;
 
+  /// Initialized when dart:mirrors is loaded.
+  LibraryElement mirrorsLibrary;
+
   ClassElement objectClass;
   ClassElement closureClass;
   ClassElement boundClosureClass;
@@ -361,6 +370,9 @@ abstract class Compiler implements DiagnosticListener {
   // Initialized when dart:mirrors is loaded.
   ClassElement mirrorSystemClass;
 
+  // Initialized when dart:mirrors is loaded.
+  ClassElement mirrorsUsedClass;
+
   // Initialized after mirrorSystemClass has been resolved.
   FunctionElement mirrorSystemGetNameFunction;
 
@@ -437,6 +449,7 @@ abstract class Compiler implements DiagnosticListener {
   EnqueueTask enqueuer;
   CompilerTask fileReadingTask;
   DeferredLoadTask deferredLoadTask;
+  MirrorUsageAnalyzerTask mirrorUsageAnalyzerTask;
   ContainerTracer containerTracer;
   String buildId;
 
@@ -545,6 +558,7 @@ abstract class Compiler implements DiagnosticListener {
       containerTracer = new ContainerTracer(this),
       constantHandler = new ConstantHandler(this, backend.constantSystem),
       deferredLoadTask = new DeferredLoadTask(this),
+      mirrorUsageAnalyzerTask = new MirrorUsageAnalyzerTask(this),
       enqueuer = new EnqueueTask(this)];
 
     tasks.addAll(backend.tasks);
@@ -692,8 +706,11 @@ abstract class Compiler implements DiagnosticListener {
       });
     }
     if (uri == new Uri(scheme: 'dart', path: 'mirrors')) {
+      mirrorsLibrary = library;
       mirrorSystemClass =
           findRequiredElement(library, const SourceString('MirrorSystem'));
+      mirrorsUsedClass =
+          findRequiredElement(library, const SourceString('MirrorsUsed'));
     } else if (uri == new Uri(scheme: 'dart', path: '_collection-dev')) {
       symbolImplementationClass =
           findRequiredElement(library, const SourceString('Symbol'));
@@ -898,6 +915,8 @@ abstract class Compiler implements DiagnosticListener {
         });
       }
 
+      mirrorUsageAnalyzerTask.analyzeUsage(mainApp);
+
       // In order to see if a library is deferred, we must compute the
       // compile-time constants that are metadata.  This means adding
       // something to the resolution queue.  So we cannot wait with
@@ -1181,6 +1200,10 @@ abstract class Compiler implements DiagnosticListener {
                   api.Diagnostic.HINT);
   }
 
+  void reportHere(Spannable node, String debugMessage) {

[Johnni Winther, 2013/07/30 11:15:09]

Document that this is for debugging only.

[ahe, 2013/07/30 12:05:45]

Done.

+    reportInfo(node, MessageKind.GENERIC, {'text': 'HERE: $debugMessage'});
+  }
+
   void reportInternalError(Spannable node, String message) {
     reportError(
         node, MessageKind.GENERIC, {'text': 'Internal Error: $message'});