Implement implicit constructors in mixin applications.

sdk/lib/_internal/compiler/implementation/resolution/members.dart

Index: sdk/lib/_internal/compiler/implementation/resolution/members.dart
diff --git a/sdk/lib/_internal/compiler/implementation/resolution/members.dart b/sdk/lib/_internal/compiler/implementation/resolution/members.dart
index ffd407fcd4a2d50ceea67133be87e2a38c3416a5..97a972b6a66d04e073a8e5360b2307f05179318e 100644
--- a/sdk/lib/_internal/compiler/implementation/resolution/members.dart
+++ b/sdk/lib/_internal/compiler/implementation/resolution/members.dart
@@ -308,7 +308,7 @@ class ResolverTask extends CompilerTask {
         visitor.useElement(tree, element);
         visitor.setupFunction(tree, element);
 
-        if (isConstructor) {
+        if (isConstructor && !element.isForwardingConstructor) {
           // Even if there is no initializer list we still have to do the
           // resolution in case there is an implicit super constructor call.
           InitializerResolver resolver = new InitializerResolver(visitor);
@@ -317,6 +317,8 @@ class ResolverTask extends CompilerTask {
           if (redirection != null) {
             resolveRedirectingConstructor(resolver, tree, element, redirection);
           }
+        } else if (element.isForwardingConstructor) {
+          // Initializers will be checked on the original constructor.
         } else if (tree.initializers != null) {
           error(tree, MessageKind.FUNCTION_WITH_INITIALIZER);
         }
@@ -2565,7 +2567,11 @@ class ResolverVisitor extends MappingVisitor<Element> {
       compiler.backend.registerThrowNoSuchMethod(mapping);
     }
     compiler.withCurrentElement(constructor, () {
-      FunctionExpression tree = constructor.parseNode(compiler);
+      FunctionElement target = constructor;
+      if (constructor.isForwardingConstructor) {
+        target = constructor.targetConstructor;
+      }
+      FunctionExpression tree = target.parseNode(compiler);
       compiler.resolver.resolveConstructorImplementation(constructor, tree);
     });
 
@@ -3269,9 +3275,10 @@ class ClassResolverVisitor extends TypeDefinitionVisitor {
     assert(mixinApplication.supertype == null);
     mixinApplication.supertype = supertype;
 
+    Node node = mixinApplication.parseNode(compiler);
     // Named mixin application may have an 'implements' clause.
     NamedMixinApplication namedMixinApplication =
-        mixinApplication.parseNode(compiler).asNamedMixinApplication();
+        node.asNamedMixinApplication();
     Link<DartType> interfaces = (namedMixinApplication != null)
         ? resolveInterfaces(namedMixinApplication.interfaces,
                             namedMixinApplication.superclass)
@@ -3286,6 +3293,32 @@ class ClassResolverVisitor extends TypeDefinitionVisitor {
 
     assert(mixinApplication.mixin == null);
     mixinApplication.mixin = resolveMixinFor(mixinApplication, mixinType);
+
+    // Create forwarding constructors for constructor defined in the superclass
+    // because they are now hidden by the mixin application.
+    ClassElement superclass = supertype.element;
+    superclass.forEachLocalMember((Element member) {
+      if (!member.isConstructor() || member.isSynthesized) return;

[kasperl, 2013/04/25 12:13:12]

Does this work if the superclass itself is a mixin application? Do you have a
test for that?

   class S { S.foo(); }
   class M1 { }
   class M2 { }
   class C extends S with M1, M2 { 
     C.foo() : super.foo();
   }

   main() {
     new C.foo();
   }

[karlklose, 2013/05/03 09:35:45]

I change it to work with these.

+      assert(invariant(node, !member.isFactoryConstructor(),
+             message: 'mixins cannot have factory constructors'));
+      FunctionElement constructor = member;
+      SourceString constructorName;

[kasperl, 2013/04/25 12:13:12]

Add a helper for computing the constructor name? ... and maybe a helper for
creating the forwarding constructor too?

That way, this loop becomes much more readable. Run through all the super class
constructors and create forwarders for them.

[karlklose, 2013/05/03 09:35:45]

I created a method to create the forwarding constructor.

+      if (constructor.name == superclass.name) {
+        if (constructor.computeSignature(compiler).parameterCount == 0) {
+          return;
+        }
+        constructorName = mixinApplication.name;
+      } else {
+        SourceString selector =
+            Elements.deconstructConstructorName(constructor.name, superclass);
+        constructorName =
+            Elements.constructConstructorName(mixinApplication.name, selector);
+      }
+      Element forwarder =
+          new SynthesizedConstructorElementX.forwarding(constructorName,
+              constructor, mixinApplication);
+      mixinApplication.addToScope(forwarder, compiler);

[kasperl, 2013/04/25 12:13:12]

I'd rather have a method for adding a new constructor to a mixin application.

[karlklose, 2013/05/03 09:35:45]

Done.

+    });
     mixinApplication.addDefaultConstructorIfNeeded(compiler);
     calculateAllSupertypes(mixinApplication);
   }