Allow users of the V8 API to distinguish between unset and undefined HiddenValues

test/cctest/test-api.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 19262 matching lines @@
   v8::HandleScope scope(context->GetIsolate());
   Local<Value> set_value = CompileRun("new Set();");
   Local<Object> set_object(Local<Object>::Cast(set_value));
   CHECK_EQ(0, set_object->InternalFieldCount());
   Local<Value> map_value = CompileRun("new Map();");
   Local<Object> map_object(Local<Object>::Cast(map_value));
   CHECK_EQ(0, map_object->InternalFieldCount());
 }
 
 
+THREADED_TEST(Regress2746) {
+  LocalContext context;
+  v8::HandleScope scope(context->GetIsolate());
+  Local<Object> obj = Object::New();
+  Local<String> key = String::New("key");
+  obj->SetHiddenValue(key, v8::Undefined());
+  Local<Value> value = obj->GetHiddenValue(key);
+  CHECK(!value.IsEmpty());
+  CHECK(value->IsUndefined());
+}
+
+
 #ifndef WIN32
 class ThreadInterruptTest {
  public:
   ThreadInterruptTest() : sem_(NULL), sem_value_(0) { }
   ~ThreadInterruptTest() { delete sem_; }
 
   void RunTest() {
     sem_ = i::OS::CreateSemaphore(0);
 
     InterruptThread i_thread(this);
@@ skipping 43 matching lines @@
   i::Semaphore* sem_;
   volatile int sem_value_;
 };
 
 
 THREADED_TEST(SemaphoreInterruption) {
   ThreadInterruptTest().RunTest();
 }
 
 #endif  // WIN32