Skeleton typedef type implementation

lib/compiler/implementation/typechecker.dart

Index: lib/compiler/implementation/typechecker.dart
diff --git a/lib/compiler/implementation/typechecker.dart b/lib/compiler/implementation/typechecker.dart
index aa6891976f43dcf3c4b610b6a68172a6a3a6b6b5..8c36f1f797c130ca126d8835e49d6f1753b77471 100644
--- a/lib/compiler/implementation/typechecker.dart
+++ b/lib/compiler/implementation/typechecker.dart
@@ -27,6 +27,18 @@ class TypeCheckerTask extends CompilerTask {
 interface Type {
   SourceString get name();
   Element get element();
+
+  /**
+   * Returns the unaliased type of this type.
+   *
+   * The unaliased type of a typedef'd type is the unaliased type to which its
+   * name is bound. The unaliased version of any other type is the type itself.
+   *
+   * For example, the unaliased type of [: typedef A Func<A,B>(B b) :] is the
+   * function type [: (B) -> A :] and the unaliased type of
+   * [: Func<int,String> :] is the function type [: (String) -> int :].
+   */
+  Type unalias(Compiler compiler);
 }
 
 class TypeVariableType implements Type {
@@ -36,7 +48,9 @@ class TypeVariableType implements Type {
 
   SourceString get name() => element.name;
 
-  toString() => name.slowToString();
+  Type unalias(Compiler compiler) => this;
+
+  String toString() => name.slowToString();
 }
 
 /**
@@ -59,6 +73,8 @@ class StatementType implements Type {
     return (this === other) ? this : MAYBE_RETURNING;
   }
 
+  Type unalias(Compiler compiler) => this;
+
   String toString() => stringName;
 }
 
@@ -67,7 +83,9 @@ class VoidType implements Type {
   SourceString get name() => element.name;
   final VoidElement element;
 
-  toString() => name.slowToString();
+  Type unalias(Compiler compiler) => this;
+
+  String toString() => name.slowToString();
 }
 
 class InterfaceType implements Type {
@@ -79,7 +97,9 @@ class InterfaceType implements Type {
 
   SourceString get name() => element.name;
 
-  toString() {
+  Type unalias(Compiler compiler) => this;
+
+  String toString() {
     StringBuffer sb = new StringBuffer();
     sb.add(name.slowToString());
     if (!arguments.isEmpty()) {
@@ -99,7 +119,9 @@ class FunctionType implements Type {
   FunctionType(Type this.returnType, Link<Type> this.parameterTypes,
                Element this.element);
 
-  toString() {
+  Type unalias(Compiler compiler) => this;
+
+  String toString() {
     StringBuffer sb = new StringBuffer();
     bool first = true;
     sb.add('(');
@@ -124,23 +146,60 @@ class FunctionType implements Type {
   }
 }
 
+class TypedefType implements Type {
+  final TypedefElement element;
+  final Link<Type> typeArguments;
+
+  const TypedefType(this.element,
+      [this.typeArguments = const EmptyLink<Type>()]);
+
+  SourceString get name() => element.name;
+
+  Type unalias(Compiler compiler) {
+    // TODO(ahe): This should be [ensureResolved].
+    compiler.resolveTypedef(element);
+    return element.alias.unalias(compiler);
+  }
+
+  String toString() {
+    StringBuffer sb = new StringBuffer();
+    sb.add(name.slowToString());
+    if (!typeArguments.isEmpty()) {
+      sb.add('<');
+      typeArguments.printOn(sb, ', ');
+      sb.add('>');
+    }
+    return sb.toString();
+  }
+}
+
 class Types {
+  final Compiler compiler;
+  // TODO(karlklose): should we have a class Void?
   final VoidType voidType;
   final InterfaceType dynamicType;
 
-  Types(Element dynamicElement)
-    : this.with(dynamicElement, new LibraryElement(new Script(null, null)));
+  Types(Compiler compiler, Element dynamicElement)
+    : this.with(compiler, dynamicElement,
+                new LibraryElement(new Script(null, null)));
 
-  // TODO(karlklose): should we have a class Void?
-  Types.with(Element dynamicElement, LibraryElement library)
-    : voidType = new VoidType(new VoidElement(library.entryCompilationUnit)),
+  Types.with(Compiler this.compiler,
+             Element dynamicElement,
+             LibraryElement library)
+    : voidType = new VoidType(new VoidElement(library)),
       dynamicType = new InterfaceType(dynamicElement);
 
   /** Returns true if t is a subtype of s */
   bool isSubtype(Type t, Type s) {
-    if (t === s || t === dynamicType || s === dynamicType ||
-        // TODO(karlklose): Test for s.element === compiler.objectClass.
-        s.name == const SourceString('Object')) return true;
+    if (t === s ||
+        t === dynamicType ||
+        s === dynamicType ||
+        s.element === compiler.objectClass) {
+      return true;
+    }
+    t = t.unalias(compiler);
+    s = s.unalias(compiler);
+
     if (t is VoidType) {
       return false;
     } else if (t is InterfaceType) {
@@ -155,6 +214,7 @@ class Types {
       }
       return false;
     } else if (t is FunctionType) {
+      if (s.element === compiler.functionClass) return true;
       if (s is !FunctionType) return false;
       FunctionType tf = t;
       FunctionType sf = s;