Fix equality of implicit closures in the Dart VM.

runtime/vm/class_finalizer.cc

Index: runtime/vm/class_finalizer.cc
===================================================================
--- runtime/vm/class_finalizer.cc	(revision 25920)
+++ runtime/vm/class_finalizer.cc	(working copy)
@@ -1528,9 +1528,6 @@
                   name.ToCString());
     }
     cls.set_is_type_finalized();
-    // Signature classes extend Object. No need to add this class to the direct
-    // subclasses of Object.
-    ASSERT(super_type.IsNull() || super_type.IsObjectType());

[Florian Schneider, 2013/08/12 18:03:06]

Do we rely on this assertion somewhere else?

 
     // The type parameters of signature classes may have bounds.
     FinalizeUpperBounds(cls);
@@ -1880,10 +1877,14 @@
       CLASS_LIST_TYPED_DATA(DO_NOT_EXTEND_TYPED_DATA_CLASSES)
 #undef DO_NOT_EXTEND_TYPED_DATA_CLASSES
       case kByteDataViewCid:
-      case kDartFunctionCid:
       case kWeakPropertyCid:
         is_error = true;
         break;
+      case kDartFunctionCid:
+        // Signature classes, which are compiler generated and represent a

[Ivan Posva, 2013/08/13 07:35:09]

I don't think this is a valid restriction.

[Florian Schneider, 2013/08/13 14:52:20]

Done.

+        // function type, are allowed to extend the Function class.
+        if (!cls.IsSignatureClass()) is_error = true;
+        break;
       default: {
         // Special case: classes for which we don't have a known class id.
         if (super_type.IsDoubleType() ||
@@ -1935,7 +1936,7 @@
           interface.IsIntType() ||
           interface.IsDoubleType() ||
           interface.IsStringType() ||
-          (interface.IsFunctionType() && !cls.IsSignatureClass()) ||
+          interface.IsFunctionType() ||
           interface.IsDynamicType()) {
         const Script& script = Script::Handle(cls.script());
         ReportError(script, cls.token_pos(),