Confusion on changing data property callback attributes

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 1986 matching lines @@
   LocalContext env;
   env->Global()->Set(v8_str("Child"), child->GetFunction());
   CompileRun("var child = new Child;"
              "child.age = 10;");
   ExpectBoolean("child.hasOwnProperty('age')", false);
   ExpectInt32("child.age", 10);
   ExpectInt32("child.accessor_age", 10);
 }
 
 
+THREADED_TEST(ExecutableAccessorIsPreservedOnAttributeChange) {
+  v8::Isolate* isolate = CcTest::isolate();
+  v8::HandleScope scope(isolate);
+  LocalContext env;
+  v8::Local<v8::Value> res = CompileRun("var a = []; a;");
+  i::Handle<i::JSObject> a(v8::Utils::OpenHandle(v8::Object::Cast(*res)));
+  CHECK(a->map()->instance_descriptors()->IsFixedArray());
+  CHECK_GT(i::FixedArray::cast(a->map()->instance_descriptors())->length(), 0);
+  CompileRun("Object.defineProperty(a, 'length', { writable: false });");
+  CHECK_EQ(i::FixedArray::cast(a->map()->instance_descriptors())->length(), 0);
+  // But we should still have an ExecutableAccessorInfo.
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  i::LookupResult lookup(i_isolate);
+  i::Handle<i::String> name(v8::Utils::OpenHandle(*v8_str("length")));
+  a->LookupOwnRealNamedProperty(name, &lookup);
+  CHECK(lookup.IsPropertyCallbacks());
+  i::Handle<i::Object> callback(lookup.GetCallbackObject(), i_isolate);
+  CHECK(callback->IsExecutableAccessorInfo());
+}
+
+
 THREADED_TEST(EmptyInterceptorBreakTransitions) {
   v8::HandleScope scope(CcTest::isolate());
   Handle<FunctionTemplate> templ = FunctionTemplate::New(CcTest::isolate());
   AddInterceptor(templ, EmptyInterceptorGetter, EmptyInterceptorSetter);
   LocalContext env;
   env->Global()->Set(v8_str("Constructor"), templ->GetFunction());
   CompileRun("var o1 = new Constructor;"
              "o1.a = 1;"  // Ensure a and x share the descriptor array.
              "Object.defineProperty(o1, 'x', {value: 10});");
   CompileRun("var o2 = new Constructor;"
@@ skipping 20621 matching lines @@
   Local<Script> script = v8::ScriptCompiler::Compile(
       isolate, &script_source);
   Local<Value> script_name = script->GetUnboundScript()->GetScriptName();
   CHECK(!script_name.IsEmpty());
   CHECK(script_name->IsString());
   String::Utf8Value utf8_name(script_name);
   CHECK_EQ(url, *utf8_name);
   int line_number = script->GetUnboundScript()->GetLineNumber(0);
   CHECK_EQ(13, line_number);
 }