Collect the types used in is-checks in the resolver phase.

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;
 
   void check(Node tree, TreeElements elements) {
     measure(() {
       Visitor visitor =
           new TypeCheckerVisitor(compiler, elements, compiler.types);
       try {
         tree.accept(visitor);
       } on CancelTypeCheckException catch (e) {
         if (LOG_FAILURES) {
           // Do not warn about unimplemented features; log message instead.
           compiler.log("'${e.node}': ${e.reason}");
         }
       }
     });
   }
 }
 
-interface Type {
-  SourceString get name();
-  Element get element();
+abstract class Type implements Hashable {
+  abstract SourceString get name();
+  abstract 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);
+  abstract Type unalias(Compiler compiler);
+
+  abstract bool equals(other);
 }
 
 class TypeVariableType implements Type {
   final TypeVariableElement element;
 
   TypeVariableType(this.element);
 
   SourceString get name => element.name;
 
   Type unalias(Compiler compiler) => this;
 
+  int hashCode() => 17 * element.hashCode();
+
+  bool equals(other) {
+    if (other is !TypeVariableType) return false;
+    return other.element == element;
+  }
+
   String toString() => name.slowToString();
 }
 
 /**
  * A statement type tracks whether a statement returns or may return.
  */
 class StatementType implements Type {
   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;
   }
 
   Type unalias(Compiler compiler) => this;
 
+  int hashCode() => 17 * stringName.hashCode();
+
+  bool equals(other) {
+    if (other is !StatementType) return false;
+    return other.stringName == stringName;
+  }
+
   String toString() => stringName;
 }
 
 class VoidType implements Type {
   const VoidType(this.element);
   SourceString get name => element.name;
   final VoidElement element;
 
   Type unalias(Compiler compiler) => this;
 
+  int hashCode() => 1729;
+
+  bool equals(other) => other is VoidType;
+
   String toString() => name.slowToString();
 }
 
 class InterfaceType implements Type {
   final Element element;
   final Link<Type> arguments;
 
   const InterfaceType(this.element,
                       [this.arguments = const EmptyLink<Type>()]);
 
   SourceString get name => element.name;
 
   Type unalias(Compiler compiler) => this;
 
   String toString() {
     StringBuffer sb = new StringBuffer();
     sb.add(name.slowToString());
     if (!arguments.isEmpty()) {
       sb.add('<');
       arguments.printOn(sb, ', ');
       sb.add('>');
     }
     return sb.toString();
   }
+
+  int hashCode() {
+    int hash = element.hashCode();
+    for (Link<Type> arguments = this.arguments;
+         !arguments.isEmpty();
+         arguments = arguments.tail) {
+      hash = 17 * hash + 3 * arguments.head.hashCode();
+    }
+    return hash;
+  }
+
+  bool equals(other) {
+    if (other is !InterfaceType) return false;
+    return arguments == other.arguments;
+  }
 }
 
 class FunctionType implements Type {
   final Element element;
   Type returnType;
   Link<Type> parameterTypes;
 
   FunctionType(Type this.returnType, Link<Type> this.parameterTypes,
                Element this.element);
 
@@ skipping 15 matching lines @@
     parameterTypes.forEach((_) { arity++; });
     return arity;
   }
 
   void initializeFrom(FunctionType other) {
     assert(returnType === null);
     assert(parameterTypes === null);
     returnType = other.returnType;
     parameterTypes = other.parameterTypes;
   }
+
+  int hashCode() {
+    int hash = 17 * element.hashCode() + 3 * returnType.hashCode();
+    for (Link<Type> parameters = parameterTypes;
+         !parameters.isEmpty();
+        parameters = parameters.tail) {
+      hash = 17 * hash + 3 * parameters.head.hashCode();
+    }
+    return hash;
+  }
+
+  bool equals(other) {
+    if (other is !FunctionType) return false;
+    return returnType == other.returnType
+           && parameterTypes == other.parameterTypes;
+  }
 }
 
 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();
   }
+
+  int hashCode() => 17 * element.hashCode();
+
+  bool equals(other) {
+    if (other is !TypedefType) return false;
+    return other.element == element;
+  }
 }
 
 class Types {
   final Compiler compiler;
   // TODO(karlklose): should we have a class Void?
   final VoidType voidType;
   final InterfaceType dynamicType;
 
   Types(Compiler compiler, Element dynamicElement)
     : this.with(compiler, dynamicElement,
@@ skipping 659 matching lines @@
   }
 
   visitCatchBlock(CatchBlock node) {
     return unhandledStatement();
   }
 
   visitTypedef(Typedef node) {
     return unhandledStatement();
   }
 }