Further work towards an exact GC

Add some more convenience in the helper classes
in qscopedvalue_p.h
Make accesses to CallData safer, and change
ExecutionEngine::newObject() to return a safe
pointer.

Change-Id: I980909754ce9681cf6faa1355bab3a1e5d6dd186
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>

8 files changed, 107 insertions, 60 deletions

diff --git a/src/qml/qml/qqmlcomponent.cpp b/src/qml/qml/qqmlcomponent.cpp
index 5ed75a1e06..149cbf2c49 100644
--- a/src/qml/qml/qqmlcomponent.cpp
+++ b/src/qml/qml/qqmlcomponent.cpp
@@ -1408,7 +1408,8 @@ void QQmlComponentPrivate::initializeObjectWithInitialProperties(const QV4::Valu
 QQmlComponentExtension::QQmlComponentExtension(QV8Engine *engine)
 {
     QV4::ExecutionEngine *v4 = QV8Engine::getV4(engine);
-    QV4::Object *proto = v4->newObject();
+    QV4::Scope scope(v4);
+    QV4::Scoped<QV4::Object> proto(scope, v4->newObject());
     QV4::Property *s = proto->insertMember(v4->newString(QStringLiteral("onStatusChanged")),
                                            QV4::Attr_Accessor|QV4::Attr_NotConfigurable|QV4::Attr_NotEnumerable);
     s->setGetter(V4FUNCTION(QmlIncubatorObject::method_get_statusChanged, v4));
@@ -1421,7 +1422,7 @@ QQmlComponentExtension::QQmlComponentExtension(QV8Engine *engine)
     s->setGetter(V4FUNCTION(QmlIncubatorObject::method_get_object, v4));
     proto->defineDefaultProperty(v4, QStringLiteral("forceCompletion"), QmlIncubatorObject::method_forceCompletion);
 
-    incubationProto = QV4::Value::fromObject(proto);
+    incubationProto = proto;
 }
 
 QV4::ReturnedValue QmlIncubatorObject::method_get_object(QV4::SimpleCallContext *ctx)
diff --git a/src/qml/qml/qqmllocale.cpp b/src/qml/qml/qqmllocale.cpp
index 405411e65c..d4998ec5ba 100644
--- a/src/qml/qml/qqmllocale.cpp
+++ b/src/qml/qml/qqmllocale.cpp
@@ -112,7 +112,7 @@ private:
 DEFINE_MANAGED_VTABLE(QQmlLocaleData);
 
 #define GET_LOCALE_DATA_RESOURCE(OBJECT) \
-    QQmlLocaleData *r = OBJECT.as<QQmlLocaleData>(); \
+    QV4::Scoped<QQmlLocaleData> r(scope, OBJECT.as<QQmlLocaleData>()); \
     if (!r) \
         V4THROW_ERROR("Not a valid Locale object")
 
@@ -140,6 +140,8 @@ QV4::ReturnedValue QQmlDateExtension::method_toLocaleString(QV4::SimpleCallConte
     if (ctx->argumentCount > 2)
         return QV4::DatePrototype::method_toLocaleString(ctx);
 
+    QV4::Scope scope(ctx);
+
     QV4::DateObject *date = ctx->thisObject.asDateObject();
     if (!date)
         return QV4::DatePrototype::method_toLocaleString(ctx);
@@ -182,6 +184,8 @@ QV4::ReturnedValue QQmlDateExtension::method_toLocaleTimeString(QV4::SimpleCallC
     if (ctx->argumentCount > 2)
         return QV4::DatePrototype::method_toLocaleTimeString(ctx);
 
+    QV4::Scope scope(ctx);
+
     QV4::DateObject *date = ctx->thisObject.asDateObject();
     if (!date)
         return QV4::DatePrototype::method_toLocaleTimeString(ctx);
@@ -225,6 +229,8 @@ QV4::ReturnedValue QQmlDateExtension::method_toLocaleDateString(QV4::SimpleCallC
     if (ctx->argumentCount > 2)
         return QV4::DatePrototype::method_toLocaleDateString(ctx);
 
+    QV4::Scope scope(ctx);
+
     QV4::DateObject *dateObj = ctx->thisObject.asDateObject();
     if (!dateObj)
         return QV4::DatePrototype::method_toLocaleDateString(ctx);
@@ -273,6 +279,8 @@ QV4::ReturnedValue QQmlDateExtension::method_fromLocaleString(QV4::SimpleCallCon
         return QV4::Encode(engine->newDateObject(dt));
     }
 
+    QV4::Scope scope(ctx);
+
     if (ctx->argumentCount < 1 || ctx->argumentCount > 3 || !isLocaleObject(ctx->arguments[0]))
         V4THROW_ERROR("Locale: Date.fromLocaleString(): Invalid arguments");
 
@@ -315,6 +323,8 @@ QV4::ReturnedValue QQmlDateExtension::method_fromLocaleTimeString(QV4::SimpleCal
     if (ctx->argumentCount < 1 || ctx->argumentCount > 3 || !isLocaleObject(ctx->arguments[0]))
         V4THROW_ERROR("Locale: Date.fromLocaleTimeString(): Invalid arguments");
 
+    QV4::Scope scope(ctx);
+
     GET_LOCALE_DATA_RESOURCE(ctx->arguments[0]);
 
     QLocale::FormatType enumFormat = QLocale::LongFormat;
@@ -355,6 +365,8 @@ QV4::ReturnedValue QQmlDateExtension::method_fromLocaleDateString(QV4::SimpleCal
     if (ctx->argumentCount < 1 || ctx->argumentCount > 3 || !isLocaleObject(ctx->arguments[0]))
         V4THROW_ERROR("Locale: Date.fromLocaleDateString(): Invalid arguments");
 
+    QV4::Scope scope(ctx);
+
     GET_LOCALE_DATA_RESOURCE(ctx->arguments[0]);
 
     QLocale::FormatType enumFormat = QLocale::LongFormat;
@@ -414,6 +426,8 @@ QV4::ReturnedValue QQmlNumberExtension::method_toLocaleString(QV4::SimpleCallCon
     if (!isLocaleObject(ctx->arguments[0]))
         return QV4::NumberPrototype::method_toLocaleString(ctx); // Use the default Number toLocaleString()
 
+    QV4::Scope scope(ctx);
+
     GET_LOCALE_DATA_RESOURCE(ctx->arguments[0]);
 
     quint16 format = 'f';
@@ -450,6 +464,8 @@ QV4::ReturnedValue QQmlNumberExtension::method_toLocaleCurrencyString(QV4::Simpl
     if (!isLocaleObject(ctx->arguments[0]))
         V4THROW_ERROR("Locale: Number.toLocaleCurrencyString(): Invalid arguments");
 
+    QV4::Scope scope(ctx);
+
     GET_LOCALE_DATA_RESOURCE(ctx->arguments[0]);
 
     QString symbol;
@@ -470,6 +486,8 @@ QV4::ReturnedValue QQmlNumberExtension::method_fromLocaleString(QV4::SimpleCallC
     int numberIdx = 0;
     QLocale locale;
 
+    QV4::Scope scope(ctx);
+
     if (ctx->argumentCount == 2) {
         if (!isLocaleObject(ctx->arguments[0]))
             V4THROW_ERROR("Locale: Number.fromLocaleString(): Invalid arguments");
@@ -671,8 +689,8 @@ public:
 QV8LocaleDataDeletable::QV8LocaleDataDeletable(QV8Engine *engine)
 {
     QV4::ExecutionEngine *eng = QV8Engine::getV4(engine);
-    QV4::Object *o = eng->newObject();
-    prototype = QV4::Value::fromObject(o);
+    QV4::Scope scope(eng);
+    QV4::Scoped<QV4::Object> o(scope, eng->newObject());
 
     o->defineDefaultProperty(eng, QStringLiteral("dateFormat"), QQmlLocaleData::method_dateFormat, 0);
     o->defineDefaultProperty(eng, QStringLiteral("standaloneDayName"), QQmlLocaleData::method_standaloneDayName, 0);
@@ -699,6 +717,8 @@ QV8LocaleDataDeletable::QV8LocaleDataDeletable(QV8Engine *engine)
     o->defineAccessorProperty(eng, QStringLiteral("amText"), QQmlLocaleData::method_get_amText, 0);
     o->defineAccessorProperty(eng, QStringLiteral("measurementSystem"), QQmlLocaleData::method_get_measurementSystem, 0);
     o->defineAccessorProperty(eng, QStringLiteral("exponential"), QQmlLocaleData::method_get_exponential, 0);
+
+    prototype = o;
 }
 
 QV8LocaleDataDeletable::~QV8LocaleDataDeletable()
diff --git a/src/qml/qml/qqmlvaluetypewrapper.cpp b/src/qml/qml/qqmlvaluetypewrapper.cpp
index f89ce15a57..b5073763b8 100644
--- a/src/qml/qml/qqmlvaluetypewrapper.cpp
+++ b/src/qml/qml/qqmlvaluetypewrapper.cpp
@@ -134,9 +134,10 @@ void QmlValueTypeWrapper::initProto(ExecutionEngine *v4)
     if (v4->qmlExtensions()->valueTypeWrapperPrototype)
         return;
 
-    Object *o = v4->newObject();
+    Scope scope(v4);
+    Scoped<Object> o(scope, v4->newObject());
     o->defineDefaultProperty(v4, QStringLiteral("toString"), method_toString, 1);
-    v4->qmlExtensions()->valueTypeWrapperPrototype = o;
+    v4->qmlExtensions()->valueTypeWrapperPrototype = o.getPointer();
 }
 
 ReturnedValue QmlValueTypeWrapper::create(QV8Engine *v8, QObject *object, int property, QQmlValueType *type)
diff --git a/src/qml/qml/qqmlxmlhttprequest.cpp b/src/qml/qml/qqmlxmlhttprequest.cpp
index dc98bd176e..bef943fd51 100644
--- a/src/qml/qml/qqmlxmlhttprequest.cpp
+++ b/src/qml/qml/qqmlxmlhttprequest.cpp
@@ -65,6 +65,7 @@
 #include <QtCore/qdebug.h>
 
 #include <private/qv4objectproto_p.h>
+#include <private/qv4scopedvalue_p.h>
 
 using namespace QV4;
 
@@ -99,15 +100,15 @@ static inline QQmlXMLHttpRequestData *xhrdata(QV8Engine *engine)
     return (QQmlXMLHttpRequestData *)engine->xmlHttpRequestData();
 }
 
-static Value constructMeObject(const Value &thisObj, QV8Engine *e)
+static ReturnedValue constructMeObject(const Value &thisObj, QV8Engine *e)
 {
     ExecutionEngine *v4 = QV8Engine::getV4(e);
     Scope scope(v4);
-    Object *meObj = v4->newObject();
+    Scoped<Object> meObj(scope, v4->newObject());
     meObj->put(v4->newString(QStringLiteral("ThisObject")), thisObj);
     ScopedValue v(scope, QmlContextWrapper::qmlScope(e, e->callingContext(), 0));
     meObj->put(v4->newString(QStringLiteral("ActivationObject")), v);
-    return Value::fromObject(meObj);
+    return meObj.asReturnedValue();
 }
 
 QQmlXMLHttpRequestData::QQmlXMLHttpRequestData()
@@ -625,10 +626,11 @@ Value Element::prototype(ExecutionEngine *engine)
 {
     QQmlXMLHttpRequestData *d = xhrdata(engine->v8Engine);
     if (d->elementPrototype.isEmpty()) {
-        Object *p = engine->newObject();
+        Scope scope(engine);
+        Scoped<Object> p(scope, engine->newObject());
         p->setPrototype(NodePrototype::getProto(engine).asObject());
         p->defineAccessorProperty(engine, QStringLiteral("tagName"), NodePrototype::method_get_nodeName, 0);
-        d->elementPrototype = Value::fromObject(p);
+        d->elementPrototype = p;
         engine->v8Engine->freezeObject(d->elementPrototype.value());
     }
     return d->elementPrototype.value();
@@ -638,12 +640,13 @@ Value Attr::prototype(ExecutionEngine *engine)
 {
     QQmlXMLHttpRequestData *d = xhrdata(engine->v8Engine);
     if (d->attrPrototype.isEmpty()) {
-        Object *p = engine->newObject();
+        Scope scope(engine);
+        Scoped<Object> p(scope, engine->newObject());
         p->setPrototype(NodePrototype::getProto(engine).asObject());
         p->defineAccessorProperty(engine, QStringLiteral("name"), method_name, 0);
         p->defineAccessorProperty(engine, QStringLiteral("value"), method_value, 0);
         p->defineAccessorProperty(engine, QStringLiteral("ownerElement"), method_ownerElement, 0);
-        d->attrPrototype = Value::fromObject(p);
+        d->attrPrototype = p;
         engine->v8Engine->freezeObject(d->attrPrototype.value());
     }
     return d->attrPrototype.value();
@@ -693,11 +696,12 @@ Value CharacterData::prototype(ExecutionEngine *v4)
 {
     QQmlXMLHttpRequestData *d = xhrdata(v4->v8Engine);
     if (d->characterDataPrototype.isEmpty()) {
-        Object *p = v4->newObject();
+        Scope scope(v4);
+        Scoped<Object> p(scope, v4->newObject());
         p->setPrototype(NodePrototype::getProto(v4).asObject());
         p->defineAccessorProperty(v4, QStringLiteral("data"), NodePrototype::method_get_nodeValue, 0);
         p->defineAccessorProperty(v4, QStringLiteral("length"), method_length, 0);
-        d->characterDataPrototype = Value::fromObject(p);
+        d->characterDataPrototype = p;
         v4->v8Engine->freezeObject(d->characterDataPrototype);
     }
     return d->characterDataPrototype.value();
@@ -725,11 +729,12 @@ Value Text::prototype(ExecutionEngine *v4)
 {
     QQmlXMLHttpRequestData *d = xhrdata(v4->v8Engine);
     if (d->textPrototype.isEmpty()) {
-        Object *p = v4->newObject();
+        Scope scope(v4);
+        Scoped<Object> p(scope, v4->newObject());
         p->setPrototype(CharacterData::prototype(v4).asObject());
         p->defineAccessorProperty(v4, QStringLiteral("isElementContentWhitespace"), method_isElementContentWhitespace, 0);
         p->defineAccessorProperty(v4, QStringLiteral("wholeText"), method_wholeText, 0);
-        d->textPrototype = Value::fromObject(p);
+        d->textPrototype = p;
         v4->v8Engine->freezeObject(d->textPrototype);
     }
     return d->textPrototype.value();
@@ -740,9 +745,10 @@ Value CDATA::prototype(ExecutionEngine *v4)
     // ### why not just use TextProto???
     QQmlXMLHttpRequestData *d = xhrdata(v4->v8Engine);
     if (d->cdataPrototype.isEmpty()) {
-        Object *p = v4->newObject();
+        Scope scope(v4);
+        Scoped<Object> p(scope, v4->newObject());
         p->setPrototype(Text::prototype(v4).asObject());
-        d->cdataPrototype = Value::fromObject(p);
+        d->cdataPrototype = p;
         v4->v8Engine->freezeObject(d->cdataPrototype);
     }
     return d->cdataPrototype.value();
@@ -752,13 +758,14 @@ Value Document::prototype(ExecutionEngine *v4)
 {
     QQmlXMLHttpRequestData *d = xhrdata(v4->v8Engine);
     if (d->documentPrototype.isEmpty()) {
-        Object *p = v4->newObject();
+        Scope scope(v4);
+        Scoped<Object> p(scope, v4->newObject());
         p->setPrototype(NodePrototype::getProto(v4).asObject());
         p->defineAccessorProperty(v4, QStringLiteral("xmlVersion"), method_xmlVersion, 0);
         p->defineAccessorProperty(v4, QStringLiteral("xmlEncoding"), method_xmlEncoding, 0);
         p->defineAccessorProperty(v4, QStringLiteral("xmlStandalone"), method_xmlStandalone, 0);
         p->defineAccessorProperty(v4, QStringLiteral("documentElement"), method_documentElement, 0);
-        d->documentPrototype = Value::fromObject(p);
+        d->documentPrototype = p;
         v4->v8Engine->freezeObject(d->documentPrototype);
     }
     return d->documentPrototype.value();
@@ -1016,9 +1023,9 @@ public:
     int replyStatus() const;
     QString replyStatusText() const;
 
-    Value open(const Value &me, const QString &, const QUrl &);
-    Value send(const Value &me, const QByteArray &);
-    Value abort(const Value &me);
+    ReturnedValue open(const ValueRef me, const QString &, const QUrl &);
+    ReturnedValue send(const ValueRef me, const QByteArray &);
+    ReturnedValue abort(const ValueRef me);
 
     void addHeader(const QString &, const QString &);
     QString header(const QString &name);
@@ -1060,11 +1067,11 @@ private:
 #endif
     void readEncoding();
 
-    Value getMe() const;
-    void setMe(const Value &me);
+    ReturnedValue getMe() const;
+    void setMe(const ValueRef me);
     PersistentValue m_me;
 
-    void dispatchCallback(const Value &me);
+    void dispatchCallback(const ValueRef me);
     void printError(const Exception &e);
 
     int m_status;
@@ -1115,8 +1122,7 @@ QString QQmlXMLHttpRequest::replyStatusText() const
     return m_statusText;
 }
 
-Value QQmlXMLHttpRequest::open(const Value &me, const QString &method,
-                                                       const QUrl &url)
+ReturnedValue QQmlXMLHttpRequest::open(const ValueRef me, const QString &method, const QUrl &url)
 {
     destroyNetwork();
     m_sendFlag = false;
@@ -1127,7 +1133,7 @@ Value QQmlXMLHttpRequest::open(const Value &me, const QString &method,
     m_state = Opened;
     m_addedHeaders.clear();
     dispatchCallback(me);
-    return Value::undefinedValue();
+    return Encode::undefined();
 }
 
 void QQmlXMLHttpRequest::addHeader(const QString &name, const QString &value)
@@ -1241,7 +1247,7 @@ void QQmlXMLHttpRequest::requestFromUrl(const QUrl &url)
                      this, SLOT(finished()));
 }
 
-Value QQmlXMLHttpRequest::send(const Value &me, const QByteArray &data)
+ReturnedValue QQmlXMLHttpRequest::send(const ValueRef me, const QByteArray &data)
 {
     m_errorFlag = false;
     m_sendFlag = true;
@@ -1252,10 +1258,10 @@ Value QQmlXMLHttpRequest::send(const Value &me, const QByteArray &data)
 
     requestFromUrl(m_url);
 
-    return Value::undefinedValue();
+    return Encode::undefined();
 }
 
-Value QQmlXMLHttpRequest::abort(const Value &me)
+ReturnedValue QQmlXMLHttpRequest::abort(const ValueRef me)
 {
     destroyNetwork();
     m_responseEntityBody = QByteArray();
@@ -1273,15 +1279,15 @@ Value QQmlXMLHttpRequest::abort(const Value &me)
 
     m_state = Unsent;
 
-    return Value::undefinedValue();
+    return Encode::undefined();
 }
 
-Value QQmlXMLHttpRequest::getMe() const
+ReturnedValue QQmlXMLHttpRequest::getMe() const
 {
-    return m_me.value();
+    return m_me.value().asReturnedValue();
 }
 
-void QQmlXMLHttpRequest::setMe(const Value &me)
+void QQmlXMLHttpRequest::setMe(const ValueRef me)
 {
     m_me = me;
 }
@@ -1293,18 +1299,22 @@ void QQmlXMLHttpRequest::readyRead()
     m_statusText =
         QString::fromUtf8(m_network->attribute(QNetworkRequest::HttpReasonPhraseAttribute).toByteArray());
 
+    Scope scope(v4);
+    ScopedValue me(scope, m_me.value());
+
     // ### We assume if this is called the headers are now available
     if (m_state < HeadersReceived) {
         m_state = HeadersReceived;
         fillHeadersList ();
-        dispatchCallback(m_me.value());
+        dispatchCallback(me);
     }
 
     bool wasEmpty = m_responseEntityBody.isEmpty();
     m_responseEntityBody.append(m_network->readAll());
     if (wasEmpty && !m_responseEntityBody.isEmpty())
         m_state = Loading;
-    dispatchCallback(m_me.value());
+
+    dispatchCallback(me);
 }
 
 static const char *errorToString(QNetworkReply::NetworkError error)
@@ -1335,6 +1345,9 @@ void QQmlXMLHttpRequest::error(QNetworkReply::NetworkError error)
         qWarning().nospace() << "    " << error << ' ' << errorToString(error) << ' ' << m_statusText;
     }
 
+    Scope scope(v4);
+    ScopedValue me(scope, m_me.value());
+
     if (error == QNetworkReply::ContentAccessDenied ||
         error == QNetworkReply::ContentOperationNotPermittedError ||
         error == QNetworkReply::ContentNotFoundError ||
@@ -1342,7 +1355,7 @@ void QQmlXMLHttpRequest::error(QNetworkReply::NetworkError error)
         error == QNetworkReply::ContentReSendError ||
         error == QNetworkReply::UnknownContentError) {
         m_state = Loading;
-        dispatchCallback(m_me.value());
+        dispatchCallback(me);
     } else {
         m_errorFlag = true;
         m_responseEntityBody = QByteArray();
@@ -1350,7 +1363,7 @@ void QQmlXMLHttpRequest::error(QNetworkReply::NetworkError error)
 
     m_state = Done;
 
-    dispatchCallback(m_me.value());
+    dispatchCallback(me);
 }
 
 #define XMLHTTPREQUEST_MAXIMUM_REDIRECT_RECURSION 15
@@ -1405,7 +1418,9 @@ void QQmlXMLHttpRequest::finished()
 
     dispatchCallback(m_me);
 
-    setMe(Value::emptyValue());
+    Scope scope(v4);
+    ScopedValue v(scope, Value::emptyValue());
+    setMe(v);
 }
 
 
@@ -1483,12 +1498,12 @@ const QByteArray &QQmlXMLHttpRequest::rawResponseBody() const
     return m_responseEntityBody;
 }
 
-void QQmlXMLHttpRequest::dispatchCallback(const Value &me)
+void QQmlXMLHttpRequest::dispatchCallback(const ValueRef me)
 {
     ExecutionContext *ctx = v4->current;
     QV4::Scope scope(v4);
     try {
-        Object *o = me.asObject();
+        Scoped<Object> o(scope, me);
         if (!o)
             ctx->throwError(QStringLiteral("QQmlXMLHttpRequest: internal error: empty ThisObject"));
 
@@ -1631,7 +1646,9 @@ DEFINE_MANAGED_VTABLE(QQmlXMLHttpRequestCtor);
 void QQmlXMLHttpRequestCtor::setupProto()
 {
     ExecutionEngine *v4 = engine();
-    proto = v4->newObject();
+    Scope scope(v4);
+    Scoped<Object> p(scope, v4->newObject());
+    proto = p.getPointer();
 
     // Methods
     proto->defineDefaultProperty(v4, QStringLiteral("open"), method_open);
@@ -1704,7 +1721,8 @@ ReturnedValue QQmlXMLHttpRequestCtor::method_open(SimpleCallContext *ctx)
     if (!username.isNull()) url.setUserName(username);
     if (!password.isNull()) url.setPassword(password);
 
-    return r->open(constructMeObject(ctx->thisObject, engine), method, url).asReturnedValue();
+    ScopedValue meObject(scope, constructMeObject(ctx->thisObject, engine));
+    return r->open(meObject, method, url);
 }
 
 ReturnedValue QQmlXMLHttpRequestCtor::method_setRequestHeader(SimpleCallContext *ctx)
@@ -1774,7 +1792,8 @@ ReturnedValue QQmlXMLHttpRequestCtor::method_send(SimpleCallContext *ctx)
     if (ctx->argumentCount > 0)
         data = ctx->arguments[0].toQStringNoThrow().toUtf8();
 
-    return r->send(constructMeObject(ctx->thisObject, engine), data).asReturnedValue();
+    ScopedValue meObject(scope, constructMeObject(ctx->thisObject, engine));
+    return r->send(meObject, data);
 }
 
 ReturnedValue QQmlXMLHttpRequestCtor::method_abort(SimpleCallContext *ctx)
@@ -1786,7 +1805,8 @@ ReturnedValue QQmlXMLHttpRequestCtor::method_abort(SimpleCallContext *ctx)
         V4THROW_REFERENCE("Not an XMLHttpRequest object");
     QQmlXMLHttpRequest *r = w->request;
 
-    return r->abort(constructMeObject(ctx->thisObject, ctx->engine->v8Engine)).asReturnedValue();
+    ScopedValue meObject(scope, constructMeObject(ctx->thisObject, ctx->engine->v8Engine));
+    return r->abort(meObject);
 }
 
 ReturnedValue QQmlXMLHttpRequestCtor::method_getResponseHeader(SimpleCallContext *ctx)
diff --git a/src/qml/qml/v8/qqmlbuiltinfunctions.cpp b/src/qml/qml/v8/qqmlbuiltinfunctions.cpp
index 6389ad2715..40b5075ddd 100644
--- a/src/qml/qml/v8/qqmlbuiltinfunctions.cpp
+++ b/src/qml/qml/v8/qqmlbuiltinfunctions.cpp
@@ -962,12 +962,12 @@ ReturnedValue QtObject::method_createQmlObject(SimpleCallContext *ctx)
             for (int ii = 0; ii < errors.count(); ++ii) {
                 const QQmlError &error = errors.at(ii);
                 errorstr += QLatin1String("\n    ") + error.toString();
-                QV4::Object *qmlerror = v4->newObject();
+                QV4::Scoped<QV4::Object> qmlerror(scope, v4->newObject());
                 qmlerror->put(v4->newString("lineNumber"), QV4::Value::fromInt32(error.line()));
                 qmlerror->put(v4->newString("columnNumber"), QV4::Value::fromInt32(error.column()));
                 qmlerror->put(v4->newString("fileName"), Value::fromString(v4->newString(error.url().toString())));
                 qmlerror->put(v4->newString("message"), Value::fromString(v4->newString(error.description())));
-                qmlerrors->putIndexed(ii, QV4::Value::fromObject(qmlerror));
+                qmlerrors->putIndexed(ii, qmlerror.asValue());
             }
 
             Scoped<Object> errorObject(scope, v4->newErrorObject(Value::fromString(v4->newString(errorstr))));
@@ -1001,7 +1001,8 @@ ReturnedValue QtObject::method_createQmlObject(SimpleCallContext *ctx)
         url = context->resolvedUrl(url);
 
     QObject *parentArg = 0;
-    if (QV4::QObjectWrapper *qobjectWrapper = ctx->arguments[1].as<QV4::QObjectWrapper>())
+    QV4::Scoped<QV4::QObjectWrapper> qobjectWrapper(scope, ctx->arguments[1]);
+    if (!!qobjectWrapper)
         parentArg = qobjectWrapper->object();
     if (!parentArg)
         V4THROW_ERROR("Qt.createQmlObject(): Missing parent object");
diff --git a/src/qml/qml/v8/qv4domerrors.cpp b/src/qml/qml/v8/qv4domerrors.cpp
index 63c79f85c2..f89831fa2f 100644
--- a/src/qml/qml/v8/qv4domerrors.cpp
+++ b/src/qml/qml/v8/qv4domerrors.cpp
@@ -48,7 +48,8 @@ using namespace QV4;
 
 void qt_add_domexceptions(ExecutionEngine *e)
 {
-    Object *domexception = e->newObject();
+    Scope scope(e);
+    Scoped<Object> domexception(scope, e->newObject());
     domexception->defineReadonlyProperty(e, QStringLiteral("INDEX_SIZE_ERR"), Value::fromInt32(DOMEXCEPTION_INDEX_SIZE_ERR));
     domexception->defineReadonlyProperty(e, QStringLiteral("DOMSTRING_SIZE_ERR"), Value::fromInt32(DOMEXCEPTION_DOMSTRING_SIZE_ERR));
     domexception->defineReadonlyProperty(e, QStringLiteral("HIERARCHY_REQUEST_ERR"), Value::fromInt32(DOMEXCEPTION_HIERARCHY_REQUEST_ERR));
@@ -66,7 +67,7 @@ void qt_add_domexceptions(ExecutionEngine *e)
     domexception->defineReadonlyProperty(e, QStringLiteral("INVALID_ACCESS_ERR"), Value::fromInt32(DOMEXCEPTION_INVALID_ACCESS_ERR));
     domexception->defineReadonlyProperty(e, QStringLiteral("VALIDATION_ERR"), Value::fromInt32(DOMEXCEPTION_VALIDATION_ERR));
     domexception->defineReadonlyProperty(e, QStringLiteral("TYPE_MISMATCH_ERR"), Value::fromInt32(DOMEXCEPTION_TYPE_MISMATCH_ERR));
-    e->globalObject->defineDefaultProperty(e->current, QStringLiteral("DOMException"), Value::fromObject(domexception));
+    e->globalObject->defineDefaultProperty(e->current, QStringLiteral("DOMException"), domexception.asValue());
 }
 
 QT_END_NAMESPACE
diff --git a/src/qml/qml/v8/qv4sqlerrors.cpp b/src/qml/qml/v8/qv4sqlerrors.cpp
index bd5a9fdc83..a203fd9980 100644
--- a/src/qml/qml/v8/qv4sqlerrors.cpp
+++ b/src/qml/qml/v8/qv4sqlerrors.cpp
@@ -49,7 +49,8 @@ using namespace QV4;
 
 void qt_add_sqlexceptions(QV4::ExecutionEngine *engine)
 {
-    Object *sqlexception = engine->newObject();
+    Scope scope(engine);
+    Scoped<Object> sqlexception(scope, engine->newObject());
     sqlexception->defineReadonlyProperty(engine, QStringLiteral("UNKNOWN_ERR"), Value::fromInt32(SQLEXCEPTION_UNKNOWN_ERR));
     sqlexception->defineReadonlyProperty(engine, QStringLiteral("DATABASE_ERR"), Value::fromInt32(SQLEXCEPTION_DATABASE_ERR));
     sqlexception->defineReadonlyProperty(engine, QStringLiteral("VERSION_ERR"), Value::fromInt32(SQLEXCEPTION_VERSION_ERR));
@@ -58,7 +59,7 @@ void qt_add_sqlexceptions(QV4::ExecutionEngine *engine)
     sqlexception->defineReadonlyProperty(engine, QStringLiteral("SYNTAX_ERR"), Value::fromInt32(SQLEXCEPTION_SYNTAX_ERR));
     sqlexception->defineReadonlyProperty(engine, QStringLiteral("CONSTRAINT_ERR"), Value::fromInt32(SQLEXCEPTION_CONSTRAINT_ERR));
     sqlexception->defineReadonlyProperty(engine, QStringLiteral("TIMEOUT_ERR"), Value::fromInt32(SQLEXCEPTION_TIMEOUT_ERR));
-    engine->globalObject->defineDefaultProperty(engine->current, QStringLiteral("SQLException"), Value::fromObject(sqlexception));
+    engine->globalObject->defineDefaultProperty(engine->current, QStringLiteral("SQLException"), sqlexception.asValue());
 }
 
 QT_END_NAMESPACE
diff --git a/src/qml/qml/v8/qv8engine.cpp b/src/qml/qml/v8/qv8engine.cpp
index 08bbd4c960..b62d8c173d 100644
--- a/src/qml/qml/v8/qv8engine.cpp
+++ b/src/qml/qml/v8/qv8engine.cpp
@@ -212,10 +212,11 @@ static QV4::ReturnedValue arrayFromVariantList(QV8Engine *engine, const QVariant
 static QV4::ReturnedValue objectFromVariantMap(QV8Engine *engine, const QVariantMap &map)
 {
     QV4::ExecutionEngine *e = QV8Engine::getV4(engine);
-    QV4::Object *o = e->newObject();
+    QV4::Scope scope(e);
+    QV4::Scoped<QV4::Object> o(scope, e->newObject());
     for (QVariantMap::ConstIterator iter = map.begin(); iter != map.end(); ++iter)
         o->put(e->newString(iter.key()), QV4::Value::fromReturnedValue(engine->fromVariant(iter.value())));
-    return QV4::Value::fromObject(o).asReturnedValue();
+    return o.asReturnedValue();
 }
 
 Q_CORE_EXPORT QString qt_regexp_toCanonical(const QString &, QRegExp::PatternSyntax);
@@ -566,13 +567,14 @@ QVariantList QV8Engine::variantListFromJS(QV4::ArrayObject *a,
 // the QVariantMap converted to JS, recursively.
 QV4::ReturnedValue QV8Engine::variantMapToJS(const QVariantMap &vmap)
 {
-    QV4::Object *o = m_v4Engine->newObject();
+    QV4::Scope scope(m_v4Engine);
+    QV4::Scoped<QV4::Object> o(scope, m_v4Engine->newObject());
     QVariantMap::const_iterator it;
     for (it = vmap.constBegin(); it != vmap.constEnd(); ++it) {
         QV4::Property *p = o->insertMember(m_v4Engine->newIdentifier(it.key()), QV4::Attr_Data);
         p->value = QV4::Value::fromReturnedValue(variantToJS(it.value()));
     }
-    return QV4::Value::fromObject(o).asReturnedValue();
+    return o.asReturnedValue();
 }
 
 // Converts a JS Object to a QVariantMap.