From a92d237948fa8a696b549efae88d5dd5c4da8208 Mon Sep 17 00:00:00 2001
From: "svenpanne@chromium.org"
 <svenpanne@chromium.org@ce2b1a6d-e550-0410-aec6-3dcde31c8c00>
Date: Wed, 26 Jun 2013 08:00:05 +0000
Subject: [PATCH] Allow users of the V8 API to distinguish between unset and
 undefined HiddenValues

BUG=v8:2746
R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/17781002

Patch from Adam Klein <adamk@chromium.org>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15329 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
---
 src/api.cc              |  2 +-
 src/objects.cc          |  7 +++----
 src/objects.h           |  2 +-
 src/runtime.cc          |  1 +
 test/cctest/test-api.cc | 12 ++++++++++++
 5 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/src/api.cc b/src/api.cc
index 8ca858d..014d82e 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -3935,7 +3935,7 @@ v8::Local<v8::Value> v8::Object::GetHiddenValue(v8::Handle<v8::String> key) {
   i::Handle<i::String> key_string =
       isolate->factory()->InternalizeString(key_obj);
   i::Handle<i::Object> result(self->GetHiddenProperty(*key_string), isolate);
-  if (result->IsUndefined()) return v8::Local<v8::Value>();
+  if (result->IsTheHole()) return v8::Local<v8::Value>();
   return Utils::ToLocal(result);
 }
 
diff --git a/src/objects.cc b/src/objects.cc
index 8633012..5265901 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -4734,7 +4734,7 @@ Object* JSObject::GetHiddenProperty(Name* key) {
     // For a proxy, use the prototype as target object.
     Object* proxy_parent = GetPrototype();
     // If the proxy is detached, return undefined.
-    if (proxy_parent->IsNull()) return GetHeap()->undefined_value();
+    if (proxy_parent->IsNull()) return GetHeap()->the_hole_value();
     ASSERT(proxy_parent->IsJSGlobalObject());
     return JSObject::cast(proxy_parent)->GetHiddenProperty(key);
   }
@@ -4748,15 +4748,14 @@ Object* JSObject::GetHiddenProperty(Name* key) {
     if (key == GetHeap()->identity_hash_string()) {
       return inline_value;
     } else {
-      return GetHeap()->undefined_value();
+      return GetHeap()->the_hole_value();
     }
   }
 
-  if (inline_value->IsUndefined()) return GetHeap()->undefined_value();
+  if (inline_value->IsUndefined()) return GetHeap()->the_hole_value();
 
   ObjectHashTable* hashtable = ObjectHashTable::cast(inline_value);
   Object* entry = hashtable->Lookup(key);
-  if (entry->IsTheHole()) return GetHeap()->undefined_value();
   return entry;
 }
 
diff --git a/src/objects.h b/src/objects.h
index 2e2a018..d3abed1 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -1996,7 +1996,7 @@ class JSObject: public JSReceiver {
                                           Handle<Object> value);
   // Returns a failure if a GC is required.
   MUST_USE_RESULT MaybeObject* SetHiddenProperty(Name* key, Object* value);
-  // Gets the value of a hidden property with the given key. Returns undefined
+  // Gets the value of a hidden property with the given key. Returns the hole
   // if the property doesn't exist (or if called on a detached proxy),
   // otherwise returns the value set for the key.
   Object* GetHiddenProperty(Name* key);
diff --git a/src/runtime.cc b/src/runtime.cc
index 8917c58..86f7f0f 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -13380,6 +13380,7 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_GetOverflowedStackTrace) {
   CONVERT_ARG_CHECKED(JSObject, error_object, 0);
   String* key = isolate->heap()->hidden_stack_trace_string();
   Object* result = error_object->GetHiddenProperty(key);
+  if (result->IsTheHole()) result = isolate->heap()->undefined_value();
   RUNTIME_ASSERT(result->IsJSArray() ||
                  result->IsString() ||
                  result->IsUndefined());
diff --git a/test/cctest/test-api.cc b/test/cctest/test-api.cc
index c39b429..b95f292 100755
--- a/test/cctest/test-api.cc
+++ b/test/cctest/test-api.cc
@@ -19280,6 +19280,18 @@ THREADED_TEST(Regress2535) {
 }
 
 
+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:
-- 
2.7.4