DartType equals converted to operator == and tested.

lib/compiler/implementation/typechecker.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 class TypeCheckerTask extends CompilerTask {
   TypeCheckerTask(Compiler compiler) : super(compiler);
   String get name => "Type checker";
 
   static const bool LOG_FAILURES = false;
 
@@ skipping 22 matching lines @@
    *
    * 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 :].
    */
   abstract DartType unalias(Compiler compiler);
 
-  abstract bool equals(other);
+  abstract bool operator ==(other);
 }
 
 class TypeVariableType implements DartType {
   final TypeVariableElement element;
 
   TypeVariableType(this.element);
 
   SourceString get name => element.name;
 
   DartType unalias(Compiler compiler) => this;
 
   int hashCode() => 17 * element.hashCode();
 
-  bool equals(other) {
+  bool operator ==(other) {
     if (other is !TypeVariableType) return false;
-    return other.element == element;
+    return other.element === element;
   }
 
   String toString() => name.slowToString();
 }
 
 /**
  * A statement type tracks whether a statement returns or may return.
  */
 class StatementType implements DartType {
   final String stringName;
   Element get element => null;
 
   SourceString get name => new SourceString(stringName);
 
   const StatementType(this.stringName);
 
   static const RETURNING = const StatementType('<returning>');
   static const NOT_RETURNING = const StatementType('<not returning>');
   static const MAYBE_RETURNING = const StatementType('<maybe returning>');
 
   /** Combine the information about two control-flow edges that are joined. */
   StatementType join(StatementType other) {
     return (this === other) ? this : MAYBE_RETURNING;
   }
 
   DartType unalias(Compiler compiler) => this;
 
   int hashCode() => 17 * stringName.hashCode();
 
-  bool equals(other) {
+  bool operator ==(other) {
     if (other is !StatementType) return false;
     return other.stringName == stringName;
   }
 
   String toString() => stringName;
 }
 
 class VoidType implements DartType {
   const VoidType(this.element);
   SourceString get name => element.name;
   final VoidElement element;
 
   DartType unalias(Compiler compiler) => this;
 
   int hashCode() => 1729;
 
-  bool equals(other) => other is VoidType;
+  bool operator ==(other) => other is VoidType;
 
   String toString() => name.slowToString();
 }
 
 class InterfaceType implements DartType {
   final Element element;
   final Link<DartType> arguments;
 
   const InterfaceType(this.element,
                       [this.arguments = const EmptyLink<DartType>()]);
@@ skipping 17 matching lines @@
     int hash = element.hashCode();
     for (Link<DartType> arguments = this.arguments;
          !arguments.isEmpty();
          arguments = arguments.tail) {
       int argumentHash = arguments.head != null ? arguments.head.hashCode() : 0;
       hash = 17 * hash + 3 * argumentHash;
     }
     return hash;
   }
 
-  bool equals(other) {
+  bool operator ==(other) {
     if (other is !InterfaceType) return false;
+    if (element !== other.element) return false;
     return arguments == other.arguments;
   }
 }
 
 class FunctionType implements DartType {
   final Element element;
   DartType returnType;
   Link<DartType> parameterTypes;
 
   FunctionType(DartType this.returnType, Link<DartType> this.parameterTypes,
@@ skipping 28 matching lines @@
   int hashCode() {
     int hash = 17 * element.hashCode() + 3 * returnType.hashCode();
     for (Link<DartType> parameters = parameterTypes;
          !parameters.isEmpty();
         parameters = parameters.tail) {
       hash = 17 * hash + 3 * parameters.head.hashCode();
     }
     return hash;
   }
 
-  bool equals(other) {
+  bool operator ==(other) {
     if (other is !FunctionType) return false;
     return returnType == other.returnType
            && parameterTypes == other.parameterTypes;
   }
 }
 
 class TypedefType implements DartType {
   final TypedefElement element;
   final Link<DartType> typeArguments;
 
@@ skipping 14 matching lines @@
     if (!typeArguments.isEmpty()) {
       sb.add('<');
       typeArguments.printOn(sb, ', ');
       sb.add('>');
     }
     return sb.toString();
   }
 
   int hashCode() => 17 * element.hashCode();
 
-  bool equals(other) {
+  bool operator ==(other) {
     if (other is !TypedefType) return false;
-    return other.element == element;
+    if (element !== other.element) return false;
+    return typeArguments == other.typeArguments;
   }
 }
 
 class Types {
   final Compiler compiler;
   // TODO(karlklose): should we have a class Void?
   final VoidType voidType;
   final InterfaceType dynamicType;
 
   Types(Compiler compiler, Element dynamicElement)
@@ skipping 662 matching lines @@
   }
 
   visitCatchBlock(CatchBlock node) {
     return unhandledStatement();
   }
 
   visitTypedef(Typedef node) {
     return unhandledStatement();
   }
 }