Emit declarations for typedefs that are needed by reflection.

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

Index: sdk/lib/_internal/compiler/implementation/js_emitter/code_emitter_task.dart
diff --git a/sdk/lib/_internal/compiler/implementation/js_emitter/code_emitter_task.dart b/sdk/lib/_internal/compiler/implementation/js_emitter/code_emitter_task.dart
index 7113389e597380d4f76f9d82e59430ff10ccef80..3888d0917ab32ba3ff9a9c792f292f9001cdc207 100644
--- a/sdk/lib/_internal/compiler/implementation/js_emitter/code_emitter_task.dart
+++ b/sdk/lib/_internal/compiler/implementation/js_emitter/code_emitter_task.dart
@@ -55,6 +55,8 @@ class CodeEmitterTask extends CompilerTask {
   // TODO(ngeoffray): remove this field.
   Set<ClassElement> instantiatedClasses;
 
+  List<TypedefElement> typedefsNeededForReflection;
+
   JavaScriptBackend get backend => compiler.backend;
   TypeVariableHandler get typeVariableHandler => backend.typeVariableHandler;
 
@@ -63,9 +65,12 @@ class CodeEmitterTask extends CompilerTask {
   String get n => compiler.enableMinification ? "" : "\n";
   String get N => compiler.enableMinification ? "\n" : ";\n";
 
+  CodeBuffer getBuffer(OutputUnit outputUnit) {
+    return outputBuffers.putIfAbsent(outputUnit, () => new CodeBuffer());
+  }
+
   CodeBuffer get mainBuffer {
-    return outputBuffers.putIfAbsent(compiler.deferredLoadTask.mainOutputUnit,
-        () => new CodeBuffer());
+    return getBuffer(compiler.deferredLoadTask.mainOutputUnit);
   }
 
   /**
@@ -750,6 +755,8 @@ class CodeEmitterTask extends CompilerTask {
       ClassElement cls = element;
       if (cls.isUnnamedMixinApplication) return null;
       return cls.name;
+    } else if (element.isTypedef) {
+      return element.name;
     }
     throw compiler.internalError(element,
         'Do not know how to reflect on this $element.');
@@ -859,7 +866,7 @@ class CodeEmitterTask extends CompilerTask {
     for (Element element in Elements.sortedByPosition(elements)) {
       ClassBuilder builder = new ClassBuilder(namer);
       containerBuilder.addMember(element, builder);
-      getElementDecriptor(element).properties.addAll(builder.properties);
+      getElementDescriptor(element).properties.addAll(builder.properties);
     }
   }
 
@@ -1145,10 +1152,15 @@ class CodeEmitterTask extends CompilerTask {
     }
   }
 
-  /**
-   * Compute all the classes that must be emitted.
-   */
-  void computeNeededClasses() {
+  /// Compute all the classes and typedefs that must be emitted.
+  void computeNeededDeclarations() {
+    // Compute needed typedefs.
+    typedefsNeededForReflection = Elements.sortedByPosition(
+        compiler.world.allTypedefs
+            .where(backend.isAccessibleByReflection)
+            .toList());
+
+    // Compute needed classes.
     instantiatedClasses =
         compiler.codegenWorld.instantiatedClasses.where(computeClassFilter())
             .toSet();
@@ -1303,21 +1315,17 @@ class CodeEmitterTask extends CompilerTask {
     if (uri.scheme == 'file' && compiler.outputUri != null) {
       uri = relativize(compiler.outputUri, library.canonicalUri, false);
     }
-    Map<OutputUnit, ClassBuilder> descriptors =
-        elementDescriptors[library];
+    Map<OutputUnit, ClassBuilder> descriptors = elementDescriptors[library];
 
     for (OutputUnit outputUnit in compiler.deferredLoadTask.allOutputUnits) {
-      ClassBuilder descriptor =
-          descriptors.putIfAbsent(outputUnit, () => new ClassBuilder(namer));
-      if (descriptor.properties.isEmpty) continue;
-      bool isDeferred =
-          outputUnit != compiler.deferredLoadTask.mainOutputUnit;
+      if (!descriptors.containsKey(outputUnit)) continue;
+
+      ClassBuilder descriptor = descriptors[outputUnit];
       jsAst.Fun metadata = metadataEmitter.buildMetadataFunction(library);
 
-      jsAst.ObjectInitializer initializers =
-          descriptor.toObjectInitializer();
-      CodeBuffer outputBuffer =
-          outputBuffers.putIfAbsent(outputUnit, () => new CodeBuffer());
+      jsAst.ObjectInitializer initializers = descriptor.toObjectInitializer();
+      CodeBuffer outputBuffer = getBuffer(outputUnit);
+
       int sizeBefore = outputBuffer.length;
       outputBuffers[outputUnit]
           ..write('["${library.getLibraryName()}",$_')
@@ -1343,7 +1351,7 @@ class CodeEmitterTask extends CompilerTask {
       // 'is$' method.
       typeTestEmitter.computeRequiredTypeChecks();
 
-      computeNeededClasses();
+      computeNeededDeclarations();
 
       mainBuffer.add(buildGeneratedBy());
       addComment(HOOKS_API_USAGE, mainBuffer);
@@ -1378,7 +1386,8 @@ class CodeEmitterTask extends CompilerTask {
       // Only output the classesCollector if we actually have any classes.
       if (!(nativeClasses.isEmpty &&
             compiler.codegenWorld.staticFunctionsNeedingGetter.isEmpty &&
-          outputClassLists.values.every((classList) => classList.isEmpty))) {
+          outputClassLists.values.every((classList) => classList.isEmpty) &&
+          typedefsNeededForReflection.isEmpty)) {
         // Shorten the code by using "$$" as temporary.
         classesCollector = r"$$";
         mainBuffer.add('var $classesCollector$_=$_{}$N$n');
@@ -1402,7 +1411,7 @@ class CodeEmitterTask extends CompilerTask {
       // Might create methodClosures.
       for (List<ClassElement> outputClassList in outputClassLists.values) {
         for (ClassElement element in outputClassList) {
-          generateClass(element, getElementDecriptor(element));
+          generateClass(element, getElementDescriptor(element));
         }
       }
 
@@ -1422,6 +1431,8 @@ class CodeEmitterTask extends CompilerTask {
           mainBuffer.write(';');
         }
 
+        // TODO(karlklose): document what kinds of fields this loop adds to the
+        // library class builder.
         for (Element element in elementDescriptors.keys) {
           // TODO(ahe): Should iterate over all libraries.  Otherwise, we will
           // not see libraries that only have fields.
@@ -1437,6 +1448,28 @@ class CodeEmitterTask extends CompilerTask {
           }
         }
 
+        // Emit all required typedef declarations into the main output unit.
+        // TODO(karlklose): unify required classes and typedefs to declarations
+        // and have builders for each kind.
+        for (TypedefElement typedef in typedefsNeededForReflection) {
+          OutputUnit mainUnit = compiler.deferredLoadTask.mainOutputUnit;
+          LibraryElement library = typedef.library;
+          // TODO(karlklose): add a TypedefBuilder and move this code there.
+          DartType type = typedef.alias;
+          int typeIndex = metadataEmitter.reifyType(type);
+          String typeReference =
+              encoding.encodeTypedefFieldDescriptor(typeIndex);
+          jsAst.Property descriptor = new jsAst.Property(
+              js.string(namer.classDescriptorProperty),
+              js.string(typeReference));
+          jsAst.Node declaration = new jsAst.ObjectInitializer([descriptor]);
+          String mangledName = namer.getNameX(typedef);
+          String reflectionName = getReflectionName(typedef, mangledName);
+          getElementDescriptorForOutputUnit(library, mainUnit)
+              ..addProperty(mangledName, declaration)
+              ..addProperty("+$reflectionName", js.string(''));
+        }
+
         if (!mangledFieldNames.isEmpty) {
           var keys = mangledFieldNames.keys.toList();
           keys.sort();
@@ -1689,7 +1722,7 @@ class CodeEmitterTask extends CompilerTask {
         () => new ClassBuilder(namer));
   }
 
-  ClassBuilder getElementDecriptor(Element element) {
+  ClassBuilder getElementDescriptor(Element element) {
     Element owner = element.library;
     if (!element.isTopLevel && !element.isNative) {
       // For static (not top level) elements, record their code in a buffer