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

sdk/lib/_internal/compiler/implementation/enqueue.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.
 
 part of dart2js;
 
 class EnqueueTask extends CompilerTask {
   final Enqueuer codegen;
   final Enqueuer resolution;
 
@@ skipping 370 matching lines @@
       registerNewSelector(setterName,
                           new TypedSelector(type, setter),
                           universe.fieldSetters);
     });
   }
 
   void registerIsCheck(DartType type) {
     universe.isChecks.add(type);
   }
 
+  void registerJsCall(Send node, ResolverVisitor resolver) {
+    var argNodes = node.arguments;

[sra1, 2012/11/29 00:12:51]

We should avoid parsing this string in two places.

This code should be moved into NativeEnqueuerBase.processNativeBehavior.
That runs after the native element has been 'parsed' into a set of instantiated
classes.
That way, things will work if the only String in the program comes from a DOM
call.

It also takes care of the fact that the instantiated types and returned types
are not always the same.

[ngeoffray, 2012/11/29 11:10:44]

Done.

+    if (argNodes.isEmpty) {
+      compiler.cancel("JS expression has no type", node: node);
+    }
+
+    LiteralString specLiteral = argNodes.head.asLiteralString();
+    if (specLiteral != null) {
+      // Register primitive types we know a JS can return.
+      String specString = specLiteral.dartString.slowToString();
+      for (String typeString in specString.split('|')) {
+        if (specString == 'int') {
+          registerInstantiatedClass(compiler.intClass);
+        } else if (specString == 'double') {
+          registerInstantiatedClass(compiler.doubleClass);
+        } else if (specString == 'num') {
+          registerInstantiatedClass(compiler.numClass);
+        } else if (specString == 'String') {
+          registerInstantiatedClass(compiler.stringClass);
+        } else if (specString == '=List') {
+          registerInstantiatedClass(compiler.listClass);
+        } else if (specString == 'bool') {
+          registerInstantiatedClass(compiler.boolClass);
+        } else if (specString == 'Null') {
+          registerInstantiatedClass(compiler.nullClass);
+        }
+      }
+    }
+
+    nativeEnqueuer.registerJsCall(node, resolver);
+  }
+  
+
   void forEach(f(WorkItem work)) {
     while (!queue.isEmpty) {
       f(queue.removeLast()); // TODO(kasperl): Why isn't this removeFirst?
     }
   }
 
   String toString() => 'Enqueuer($name)';
 
   void logSummary(log(message)) {
     log(isResolutionQueue
         ? 'Resolved ${resolvedElements.length} elements.'
         : 'Compiled ${universe.generatedCode.length} methods.');
     nativeEnqueuer.logSummary(log);
   }
 }