Substitution implemented for the class hierarchy.

lib/compiler/implementation/elements/elements.dart

Index: lib/compiler/implementation/elements/elements.dart
diff --git a/lib/compiler/implementation/elements/elements.dart b/lib/compiler/implementation/elements/elements.dart
index a104749521a57a0089f9f97975d1dc8d53b23074..00ead02f822f0dc39e470fa607a31239f2e76fd2 100644
--- a/lib/compiler/implementation/elements/elements.dart
+++ b/lib/compiler/implementation/elements/elements.dart
@@ -850,10 +850,39 @@ class ClassElement extends ContainerElement {
     }
   }
 
-  Type computeType(compiler) {
+  /**
+   * Called to ensure that type parameters and the type of this class have been
+   * created. The bounds of the type variables are not set here but instead
+   * during resolution of the class. This split is needed to create the type
+   * of the class before it has been resolved, which in turns enables the
+   * resolution to handle cyclic dependencies as for instance imposed by default
+   * classes.
+   */
+  void ensureParametersAndType(Compiler compiler) {
     if (type === null) {

[floitsch, 2012/07/26 11:14:40]

no need to === anymore. == is enough.

-      type = new InterfaceType(this);
+      ClassNode node = parseNode(compiler);
+      Link<Node> parameters =
+          node.typeParameters !== null ? node.typeParameters.nodes
+                                       : const EmptyLink<TypeVariable>();
+      // Create types and elements for type variable.
+      var arguments = new LinkBuilder<Type>();
+      for (Link<Node> link = parameters; !link.isEmpty(); link = link.tail) {
+        TypeVariable typeNode = link.head;
+        SourceString variableName = typeNode.name.source;
+        TypeVariableType variableType = new TypeVariableType(variableName);
+        arguments.addLast(variableType);
+        TypeVariableElement variableElement =
+            new TypeVariableElement(variableName, this, node,
+                                    variableType);
+        variableType.element = variableElement;
+        typeParameters[variableName] = variableElement;
+      }
+      type = new InterfaceType(this, arguments.toLink());
     }
+  }
+
+  Type computeType(compiler) {
+    ensureParametersAndType(compiler);
     return type;
   }