Process typedefs, referenced from the program.

lib/compiler/implementation/dart_backend/backend.dart

Index: lib/compiler/implementation/dart_backend/backend.dart
diff --git a/lib/compiler/implementation/dart_backend/backend.dart b/lib/compiler/implementation/dart_backend/backend.dart
index f64cc13d349566cde41f450b1fd8458559d471ba..1755a85dc7ddbd9317f79194d5923ee7cd555139 100644
--- a/lib/compiler/implementation/dart_backend/backend.dart
+++ b/lib/compiler/implementation/dart_backend/backend.dart
@@ -70,10 +70,17 @@ class DartBackend extends Backend {
       !isDartCoreLib(compiler, element.getLibrary());
 
     try {
+      Set<TypedefElement> typedefs = new Set<TypedefElement>();
       PlaceholderCollector collector = new PlaceholderCollector(compiler);
       resolvedElements.forEach((element, treeElements) {
         if (!shouldOutput(element)) return;
+        if (element is AbstractFieldElement) return;
         collector.collect(element, treeElements);
+        new AdditionalElementCollector(
+            compiler,

[Roman, 2012/08/09 16:48:03]

style nazi: Can you please make it more compact? It does not look nice like
this, it is also easy to skip call to collect() while reading this.

[Anton Muhin, 2012/08/09 17:01:08]

Done.

+            element, treeElements,
+            typedefs)
+            .collect();
       });
 
       ConflictingRenamer renamer =
@@ -95,6 +102,8 @@ class DartBackend extends Backend {
         emitter.outputElement(element);
       });
 
+      typedefs.forEach(emitter.outputElement);

[Roman, 2012/08/09 16:48:03]

I think we also want to traverse typedef nodes, because they can have references
to yet not used types.

PS I guess that's why the test failed. Not necessary task for this cl, just to
keep a note.

[Anton Muhin, 2012/08/09 17:01:09]

I believe we traverse those typedefs as a part of collector (it does
visitChildren).  But we just do not emit empty classes back.

On 2012/08/09 16:48:03, Roman wrote:

+
       // Now output resolved classes with inner elements we met before.
       resolvedClassMembers.forEach(emitter.outputClass);
       compiler.assembledCode = emitter.toString();
@@ -123,3 +132,29 @@ bool isDartCoreLib(Compiler compiler, LibraryElement libraryElement) {
   }
   return false;
 }
+
+class AdditionalElementCollector extends AbstractVisitor {

[Roman, 2012/08/09 16:48:03]

Please think about better name. What is "additional element" is unclear. We are
trying to collect all used types here, so maybe some name telling about type
collection?

[Anton Muhin, 2012/08/09 17:01:09]

Ok, is it any better?

On 2012/08/09 16:48:03, Roman wrote:

+  final Compiler compiler;
+  final Element element;
+  final TreeElements treeElements;
+  final Set<TypedefElement> typedefs;
+
+  AdditionalElementCollector(
+      this.compiler,
+      this.element, this.treeElements,
+      this.typedefs);
+
+  visitNode(Node node) { node.visitChildren(this); }
+
+  visitTypeAnnotation(TypeAnnotation typeAnnotation) {
+    Element element = treeElements[typeAnnotation];

[Roman, 2012/08/09 16:48:03]

I think canonically types should be resolved through treeElements.getType() . Is
there any difference if you try that?

[Anton Muhin, 2012/08/09 17:01:09]

Right now I don't want to resolve types, meaning I don't want get Type instance
back, at least for typedefs.  I might be forced to do that for classes though. 
Let's see.

On 2012/08/09 16:48:03, Roman wrote:

+    if (element !== null) {
+      if (element.isTypedef()) typedefs.add(element as TypedefElement);

[ahe, 2012/08/09 16:51:55]

The cast is unnecessary. Dart is a dynamically typed language with optional
types. Respect the dynamic nature :-)

[Anton Muhin, 2012/08/09 17:01:09]

Sure, I was just concerned if some tool will give me a warning here as a put
Element into Set<TypedefElement>.

On 2012/08/09 16:51:55, ahe wrote:

+    }
+    typeAnnotation.visitChildren(this);
+  }
+
+  void collect() {
+    element.parseNode(compiler).accept(this);
+  }
+}