- Parse the return type of JS during resolution to know what can be instantiated there.

sdk/lib/_internal/compiler/implementation/native_handler.dart

Index: sdk/lib/_internal/compiler/implementation/native_handler.dart
===================================================================
--- sdk/lib/_internal/compiler/implementation/native_handler.dart	(revision 15508)
+++ sdk/lib/_internal/compiler/implementation/native_handler.dart	(working copy)
@@ -56,7 +56,7 @@
    *
    */
   // TODO(sra): The entry from codegen will not have a resolver.
-  void registerJsCall(Send node, ResolverVisitor resolver) {}
+  void registerJsCall(Send node, Enqueuer enqueuer, ResolverVisitor resolver) {}

[sra1, 2012/11/29 16:45:50]

enqueuer already available in implementations as this.world.

 
   /// Emits a summary information using the [log] function.
   void logSummary(log(message)) {}
@@ -218,9 +218,9 @@
     flushQueue();
   }
 
-  void registerJsCall(Send node, ResolverVisitor resolver) {
+  void registerJsCall(Send node, Enqueuer enqueuer, ResolverVisitor resolver) {
     processNativeBehavior(
-        NativeBehavior.ofJsCall(node, compiler, resolver),
+        NativeBehavior.ofJsCall(node, compiler, enqueuer, resolver),
         node);
     flushQueue();
   }
@@ -401,7 +401,8 @@
 
   //NativeBehavior();
 
-  static NativeBehavior ofJsCall(Send jsCall, Compiler compiler, resolver) {
+  static NativeBehavior ofJsCall(
+      Send jsCall, Compiler compiler, Enqueuer enqueuer, resolver) {
     // The first argument of a JS-call is a string encoding various attributes
     // of the code.
     //
@@ -430,6 +431,13 @@
         var type = _parseType(typeString, compiler,
             (name) => resolver.resolveTypeFromString(name),
             jsCall);
+        if (type == SpecialType.JsArray) {
+          enqueuer.registerInstantiatedClass(compiler.listClass); 

[sra1, 2012/11/29 16:45:50]

NativeBehavior is data.  There should be no side effect of creating a
description of something's native behavior.  We could add more information from
annotations, like side-effects.

The registering should be in processNativeBehavior, so that this annotation on a
native class also does the right thing:

class MessageEvent ... native ... {

    @Creates('=List')  @Returns('=List')
    final List ports;
}

NativeEnqueuerBase already had the main enqueuer as this.world.

[ngeoffray, 2012/11/30 11:30:00]

Done.

+        } else if (type == SpecialType.JsObject) {
+          enqueuer.registerInstantiatedClass(compiler.objectClass); 
+        } else if (type is InterfaceType) {
+          enqueuer.registerInstantiatedClass(type.element); 

[sra1, 2012/11/29 16:45:50]

I assume this is how 'int' gets instantiated.

Is there a way to tell if the type is one of the small number (other than native
classes) with hidden calls to the constructors (int, bool, String, ...)

Does JS('List', ...) to instantiate compiler.listClass through this path?

I'm concerned that this path will lead to instantiating all the native types.

[ngeoffray, 2012/11/30 11:30:00]

Yeah, just unconditionally registering will lead to instantiating all the types.
I've changed the code to manually check for these primitive classes. There is no
easy way right now other than if/else, but we can think of creating a set just
for them.

+        }
         behavior.typesInstantiated.add(type);
         behavior.typesReturned.add(type);
       }