Convert most remaining return values from Value to ReturnedValue

Change-Id: If8b0c3b91be50678693868c10fefc3678008834d
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>

24 files changed, 228 insertions, 223 deletions

diff --git a/src/qml/qml/qqmlbinding.cpp b/src/qml/qml/qqmlbinding.cpp
index eff17ddd9a..a5e281dc56 100644
--- a/src/qml/qml/qqmlbinding.cpp
+++ b/src/qml/qml/qqmlbinding.cpp
@@ -244,12 +244,13 @@ void QQmlBinding::update(QQmlPropertyPrivate::WriteFlags flags)
 
         } else {
             QQmlEnginePrivate *ep = QQmlEnginePrivate::get(context()->engine);
+            QV4::Scope scope(ep->v4engine());
+
             ep->referenceScarceResources();
 
             bool isUndefined = false;
 
-            QV4::Value result =
-                    QQmlJavaScriptExpression::evaluate(context(), v4function.value(), &isUndefined);
+            QV4::ScopedValue result(scope, QQmlJavaScriptExpression::evaluate(context(), v4function.value(), &isUndefined));
 
             trace.event("writing binding result");
 
@@ -285,12 +286,12 @@ void QQmlBinding::update(QQmlPropertyPrivate::WriteFlags flags)
 QVariant QQmlBinding::evaluate()
 {
     QQmlEnginePrivate *ep = QQmlEnginePrivate::get(context()->engine);
+    QV4::Scope scope(ep->v4engine());
     ep->referenceScarceResources();
 
     bool isUndefined = false;
 
-    QV4::Value result =
-            QQmlJavaScriptExpression::evaluate(context(), v4function.value(), &isUndefined);
+    QV4::ScopedValue result(scope, QQmlJavaScriptExpression::evaluate(context(), v4function.value(), &isUndefined));
 
     ep->dereferenceScarceResources();
 
diff --git a/src/qml/qml/qqmlboundsignal.cpp b/src/qml/qml/qqmlboundsignal.cpp
index b7cb52bdbc..deb93b990d 100644
--- a/src/qml/qml/qqmlboundsignal.cpp
+++ b/src/qml/qml/qqmlboundsignal.cpp
@@ -194,7 +194,7 @@ void QQmlBoundSignalExpression::evaluate(void **a)
             //    for several cases (such as QVariant type and QObject-derived types)
             //args[ii] = engine->metaTypeToJS(type, a[ii + 1]);
             if (type == QMetaType::QVariant) {
-                args[ii] = engine->fromVariant(*((QVariant *)a[ii + 1]));
+                args[ii] = QV4::Value::fromReturnedValue(engine->fromVariant(*((QVariant *)a[ii + 1])));
             } else if (type == QMetaType::Int) {
                 //### optimization. Can go away if we switch to metaTypeToJS, or be expanded otherwise
                 args[ii] = QV4::Value::fromInt32(*reinterpret_cast<const int*>(a[ii + 1]));
@@ -204,9 +204,9 @@ void QQmlBoundSignalExpression::evaluate(void **a)
                 if (!*reinterpret_cast<void* const *>(a[ii + 1]))
                     args[ii] = QV4::Value::nullValue();
                 else
-                    args[ii] = QV4::QObjectWrapper::wrap(ep->v4engine(), *reinterpret_cast<QObject* const *>(a[ii + 1]));
+                    args[ii] = QV4::Value::fromReturnedValue(QV4::QObjectWrapper::wrap(ep->v4engine(), *reinterpret_cast<QObject* const *>(a[ii + 1])));
             } else {
-                args[ii] = engine->fromVariant(QVariant(type, a[ii + 1]));
+                args[ii] = QV4::Value::fromReturnedValue(engine->fromVariant(QVariant(type, a[ii + 1])));
             }
         }
 
diff --git a/src/qml/qml/qqmlcomponent.cpp b/src/qml/qml/qqmlcomponent.cpp
index eb5e314ead..f822728f08 100644
--- a/src/qml/qml/qqmlcomponent.cpp
+++ b/src/qml/qml/qqmlcomponent.cpp
@@ -1221,8 +1221,8 @@ void QQmlComponent::createObject(QQmlV4Function *args)
 
     QQmlComponent_setQmlParent(rv, parent);
 
-    QV4::Value object = QV4::QObjectWrapper::wrap(v4engine, rv);
-    Q_ASSERT(object.asObject());
+    QV4::ScopedValue object(scope, QV4::QObjectWrapper::wrap(v4engine, rv));
+    Q_ASSERT(object->isObject());
 
     if (!valuemap.isEmpty()) {
         QQmlComponentExtension *e = componentExtension(v8engine);
@@ -1369,8 +1369,8 @@ void QQmlComponentPrivate::initializeObjectWithInitialProperties(const QV4::Valu
     QV4::ExecutionEngine *v4engine = QV8Engine::getV4(v8engine);
     QV4::Scope scope(v4engine);
 
-    QV4::Value object = QV4::QObjectWrapper::wrap(v4engine, toCreate);
-    Q_ASSERT(object.asObject());
+    QV4::ScopedValue object(scope, QV4::QObjectWrapper::wrap(v4engine, toCreate));
+    Q_ASSERT(object->asObject());
 
     if (!valuemap.isEmpty()) {
         QQmlComponentExtension *e = componentExtension(v8engine);
@@ -1412,7 +1412,7 @@ QV4::ReturnedValue QmlIncubatorObject::method_get_object(QV4::SimpleCallContext
     if (!o)
         ctx->throwTypeError();
 
-    return QV4::QObjectWrapper::wrap(ctx->engine, o->object()).asReturnedValue();
+    return QV4::QObjectWrapper::wrap(ctx->engine, o->object());
 }
 
 QV4::ReturnedValue QmlIncubatorObject::method_forceCompletion(QV4::SimpleCallContext *ctx)
@@ -1478,7 +1478,7 @@ void QmlIncubatorObject::setInitialState(QObject *o)
         QV4::Scoped<QV4::FunctionObject> f(scope, QV4::Script::evaluate(v4, QString::fromLatin1(INITIALPROPERTIES_SOURCE), qmlGlobal.asObject()));
         QV4::ScopedCallData callData(scope, 2);
         callData->thisObject = QV4::Value::fromObject(v4->globalObject);
-        callData->args[0] = QV4::QObjectWrapper::wrap(v4, o);
+        callData->args[0] = QV4::Value::fromReturnedValue(QV4::QObjectWrapper::wrap(v4, o));
         callData->args[1] = valuemap;
         f->call(callData);
     }
diff --git a/src/qml/qml/qqmlcontextwrapper.cpp b/src/qml/qml/qqmlcontextwrapper.cpp
index f84f288770..50d1f32c10 100644
--- a/src/qml/qml/qqmlcontextwrapper.cpp
+++ b/src/qml/qml/qqmlcontextwrapper.cpp
@@ -73,15 +73,15 @@ QmlContextWrapper::~QmlContextWrapper()
         context->destroy();
 }
 
-QV4::Value QmlContextWrapper::qmlScope(QV8Engine *v8, QQmlContextData *ctxt, QObject *scope)
+ReturnedValue QmlContextWrapper::qmlScope(QV8Engine *v8, QQmlContextData *ctxt, QObject *scope)
 {
     ExecutionEngine *v4 = QV8Engine::getV4(v8);
 
     QmlContextWrapper *w = new (v4->memoryManager) QmlContextWrapper(v8, ctxt, scope);
-    return Value::fromObject(w);
+    return Value::fromObject(w).asReturnedValue();
 }
 
-QV4::Value QmlContextWrapper::urlScope(QV8Engine *v8, const QUrl &url)
+ReturnedValue QmlContextWrapper::urlScope(QV8Engine *v8, const QUrl &url)
 {
     ExecutionEngine *v4 = QV8Engine::getV4(v8);
 
@@ -92,7 +92,7 @@ QV4::Value QmlContextWrapper::urlScope(QV8Engine *v8, const QUrl &url)
 
     QmlContextWrapper *w = new (v4->memoryManager) QmlContextWrapper(v8, context, 0);
     w->isNullWrapper = true;
-    return Value::fromObject(w);
+    return Value::fromObject(w).asReturnedValue();
 }
 
 QQmlContextData *QmlContextWrapper::callingContext(ExecutionEngine *v4)
@@ -192,9 +192,9 @@ ReturnedValue QmlContextWrapper::get(Managed *m, String *name, bool *hasProperty
                 else
                     return QV4::Value::undefinedValue().asReturnedValue();
             } else if (r.type) {
-                return QmlTypeWrapper::create(engine, scopeObject, r.type).asReturnedValue();
+                return QmlTypeWrapper::create(engine, scopeObject, r.type);
             } else if (r.importNamespace) {
-                return QmlTypeWrapper::create(engine, scopeObject, context->imports, r.importNamespace).asReturnedValue();
+                return QmlTypeWrapper::create(engine, scopeObject, context->imports, r.importNamespace);
             }
             Q_ASSERT(!"Unreachable");
         }
@@ -216,7 +216,7 @@ ReturnedValue QmlContextWrapper::get(Managed *m, String *name, bool *hasProperty
                     ep->captureProperty(&context->idValues[propertyIdx].bindings);
                     if (hasProperty)
                         *hasProperty = true;
-                    return QV4::QObjectWrapper::wrap(v4, context->idValues[propertyIdx]).asReturnedValue();
+                    return QV4::QObjectWrapper::wrap(v4, context->idValues[propertyIdx]);
                 } else {
 
                     QQmlContextPrivate *cp = context->asQQmlContextPrivate();
@@ -231,9 +231,9 @@ ReturnedValue QmlContextWrapper::get(Managed *m, String *name, bool *hasProperty
                         QQmlListProperty<QObject> prop(context->asQQmlContext(), (void*) qintptr(propertyIdx),
                                                                QQmlContextPrivate::context_count,
                                                                QQmlContextPrivate::context_at);
-                        return QmlListWrapper::create(engine, prop, qMetaTypeId<QQmlListProperty<QObject> >()).asReturnedValue();
+                        return QmlListWrapper::create(engine, prop, qMetaTypeId<QQmlListProperty<QObject> >());
                     } else {
-                        return engine->fromVariant(cp->propertyValues.at(propertyIdx)).asReturnedValue();
+                        return engine->fromVariant(cp->propertyValues.at(propertyIdx));
                     }
                 }
             }
@@ -242,7 +242,8 @@ ReturnedValue QmlContextWrapper::get(Managed *m, String *name, bool *hasProperty
         // Search scope object
         if (scopeObject) {
             bool hasProp = false;
-            QV4::Value result = QV4::QObjectWrapper::getQmlProperty(v4->current, context, scopeObject, name, QV4::QObjectWrapper::CheckRevision, &hasProp);
+            QV4::ScopedValue result(scope, QV4::QObjectWrapper::getQmlProperty(v4->current, context, scopeObject,
+                                                                               name, QV4::QObjectWrapper::CheckRevision, &hasProp));
             if (hasProp) {
                 if (hasProperty)
                     *hasProperty = true;
diff --git a/src/qml/qml/qqmlcontextwrapper_p.h b/src/qml/qml/qqmlcontextwrapper_p.h
index 0ed933014b..c5f7f251c1 100644
--- a/src/qml/qml/qqmlcontextwrapper_p.h
+++ b/src/qml/qml/qqmlcontextwrapper_p.h
@@ -70,8 +70,8 @@ struct Q_QML_EXPORT QmlContextWrapper : Object
     QmlContextWrapper(QV8Engine *engine, QQmlContextData *context, QObject *scopeObject, bool ownsContext = false);
     ~QmlContextWrapper();
 
-    static QV4::Value qmlScope(QV8Engine *e, QQmlContextData *ctxt, QObject *scope);
-    static QV4::Value urlScope(QV8Engine *e, const QUrl &);
+    static ReturnedValue qmlScope(QV8Engine *e, QQmlContextData *ctxt, QObject *scope);
+    static ReturnedValue urlScope(QV8Engine *e, const QUrl &);
 
     static QQmlContextData *callingContext(ExecutionEngine *v4);
     static void takeContextOwnership(const QV4::Value &qmlglobal);
diff --git a/src/qml/qml/qqmlexpression.cpp b/src/qml/qml/qqmlexpression.cpp
index ddebf02c6c..76214c17a4 100644
--- a/src/qml/qml/qqmlexpression.cpp
+++ b/src/qml/qml/qqmlexpression.cpp
@@ -260,7 +260,7 @@ void QQmlExpression::setExpression(const QString &expression)
 }
 
 // Must be called with a valid handle scope
-QV4::Value QQmlExpressionPrivate::v4value(bool *isUndefined)
+QV4::ReturnedValue QQmlExpressionPrivate::v4value(bool *isUndefined)
 {
     if (!expressionFunctionValid) {
         function = qmlBinding(context(), scopeObject(), expression, url, line, &qmlscope);
@@ -285,7 +285,8 @@ QVariant QQmlExpressionPrivate::value(bool *isUndefined)
     ep->referenceScarceResources(); // "hold" scarce resources in memory during evaluation.
 
     {
-        QV4::Value result = v4value(isUndefined);
+        QV4::Scope scope(QV8Engine::getV4(ep->v8engine()));
+        QV4::ScopedValue result(scope, v4value(isUndefined));
         rv = ep->v8engine()->toVariant(result, -1);
     }
 
diff --git a/src/qml/qml/qqmlexpression_p.h b/src/qml/qml/qqmlexpression_p.h
index 9cc5a326f8..e84d193837 100644
--- a/src/qml/qml/qqmlexpression_p.h
+++ b/src/qml/qml/qqmlexpression_p.h
@@ -81,7 +81,7 @@ public:
 
     QVariant value(bool *isUndefined = 0);
 
-    QV4::Value v4value(bool *isUndefined = 0);
+    QV4::ReturnedValue v4value(bool *isUndefined = 0);
 
     static inline QQmlExpressionPrivate *get(QQmlExpression *expr);
     static inline QQmlExpression *get(QQmlExpressionPrivate *expr);
diff --git a/src/qml/qml/qqmljavascriptexpression.cpp b/src/qml/qml/qqmljavascriptexpression.cpp
index 322100f47e..d16d421ed2 100644
--- a/src/qml/qml/qqmljavascriptexpression.cpp
+++ b/src/qml/qml/qqmljavascriptexpression.cpp
@@ -122,15 +122,13 @@ void QQmlJavaScriptExpression::resetNotifyOnValueChanged()
     clearGuards();
 }
 
-QV4::Value
-QQmlJavaScriptExpression::evaluate(QQmlContextData *context,
+QV4::ReturnedValue QQmlJavaScriptExpression::evaluate(QQmlContextData *context,
                                    const QV4::Value &function, bool *isUndefined)
 {
     return evaluate(context, function, 0, 0, isUndefined);
 }
 
-QV4::Value
-QQmlJavaScriptExpression::evaluate(QQmlContextData *context,
+QV4::ReturnedValue QQmlJavaScriptExpression::evaluate(QQmlContextData *context,
                                    const QV4::Value &function,
                                    int argc, QV4::Value *args,
                                    bool *isUndefined)
@@ -140,7 +138,7 @@ QQmlJavaScriptExpression::evaluate(QQmlContextData *context,
     if (function.isEmpty() || function.isUndefined()) {
         if (isUndefined)
             *isUndefined = true;
-        return QV4::Value::emptyValue();
+        return QV4::Value::emptyValue().asReturnedValue();
     }
 
     QQmlEnginePrivate *ep = QQmlEnginePrivate::get(context->engine);
@@ -167,15 +165,14 @@ QQmlJavaScriptExpression::evaluate(QQmlContextData *context,
     QV4::ScopedValue result(scope, QV4::Value::undefinedValue());
     QV4::ExecutionContext *ctx = v4->current;
     try {
-        QV4::Value This = ep->v8engine()->global();
+        QV4::ScopedCallData callData(scope, argc);
+        callData->thisObject = ep->v8engine()->global();
         if (scopeObject() && requiresThisObject()) {
-            QV4::Value value = QV4::QObjectWrapper::wrap(ctx->engine, scopeObject());
-            if (value.isObject())
-                This = value;
+            QV4::ScopedValue value(scope, QV4::QObjectWrapper::wrap(ctx->engine, scopeObject()));
+            if (value->isObject())
+                callData->thisObject = value;
         }
 
-        QV4::ScopedCallData callData(scope, argc);
-        callData->thisObject = This;
         memcpy(callData->args, args, argc*sizeof(QV4::Value));
         result = function.asFunctionObject()->call(callData);
 
@@ -211,7 +208,7 @@ QQmlJavaScriptExpression::evaluate(QQmlContextData *context,
 
     ep->propertyCapture = lastPropertyCapture;
 
-    return result;
+    return result.asReturnedValue();
 }
 
 void QQmlJavaScriptExpression::GuardCapture::captureProperty(QQmlNotifier *n)
@@ -360,7 +357,7 @@ QQmlJavaScriptExpression::evalFunction(QQmlContextData *ctxt, QObject *scopeObje
     return result.asReturnedValue();
 }
 
-QV4::PersistentValue QQmlJavaScriptExpression::qmlBinding(QQmlContextData *ctxt, QObject *scope,
+QV4::PersistentValue QQmlJavaScriptExpression::qmlBinding(QQmlContextData *ctxt, QObject *qmlScope,
                                                        const QString &code, const QString &filename, quint16 line,
                                                        QV4::PersistentValue *qmlscope)
 {
@@ -369,10 +366,11 @@ QV4::PersistentValue QQmlJavaScriptExpression::qmlBinding(QQmlContextData *ctxt,
 
     QV4::ExecutionEngine *v4 = QV8Engine::getV4(ep->v8engine());
     QV4::ExecutionContext *ctx = v4->current;
+    QV4::Scope scope(v4);
 
-    QV4::Value scopeObject = QV4::QmlContextWrapper::qmlScope(ep->v8engine(), ctxt, scope);
-    QV4::Script script(v4, scopeObject.asObject(), code, filename, line);
-    QV4::Value result;
+    QV4::ScopedValue qmlScopeObject(scope, QV4::QmlContextWrapper::qmlScope(ep->v8engine(), ctxt, qmlScope));
+    QV4::Script script(v4, qmlScopeObject->asObject(), code, filename, line);
+    QV4::ScopedValue result(scope);
     try {
         script.parse();
         result = script.qmlBinding();
@@ -386,13 +384,13 @@ QV4::PersistentValue QQmlJavaScriptExpression::qmlBinding(QQmlContextData *ctxt,
             error.setLine(line);
         if (error.url().isEmpty())
             error.setUrl(QUrl::fromLocalFile(filename));
-        error.setObject(scope);
+        error.setObject(qmlScope);
         ep->warning(error);
         return QV4::PersistentValue();
     }
     if (qmlscope)
-        *qmlscope = scopeObject;
-    return result;
+        *qmlscope = qmlScopeObject;
+    return result.asReturnedValue();
 }
 
 
diff --git a/src/qml/qml/qqmljavascriptexpression_p.h b/src/qml/qml/qqmljavascriptexpression_p.h
index ef36a2f91a..f08b3af6cf 100644
--- a/src/qml/qml/qqmljavascriptexpression_p.h
+++ b/src/qml/qml/qqmljavascriptexpression_p.h
@@ -110,9 +110,9 @@ public:
 
     QQmlJavaScriptExpression(VTable *vtable);
 
-    QV4::Value evaluate(QQmlContextData *, const QV4::Value &function,
+    QV4::ReturnedValue evaluate(QQmlContextData *, const QV4::Value &function,
                                   bool *isUndefined);
-    QV4::Value evaluate(QQmlContextData *, const QV4::Value &function,
+    QV4::ReturnedValue evaluate(QQmlContextData *, const QV4::Value &function,
                                   int argc, QV4::Value *args,
                                   bool *isUndefined);
 
diff --git a/src/qml/qml/qqmllistwrapper.cpp b/src/qml/qml/qqmllistwrapper.cpp
index e8f01bbc08..23aca851a6 100644
--- a/src/qml/qml/qqmllistwrapper.cpp
+++ b/src/qml/qml/qqmllistwrapper.cpp
@@ -63,10 +63,10 @@ QmlListWrapper::~QmlListWrapper()
 {
 }
 
-Value QmlListWrapper::create(QV8Engine *v8, QObject *object, int propId, int propType)
+ReturnedValue QmlListWrapper::create(QV8Engine *v8, QObject *object, int propId, int propType)
 {
     if (!object || propId == -1)
-        return Value::nullValue();
+        return Encode::null();
 
     ExecutionEngine *v4 = QV8Engine::getV4(v8);
 
@@ -75,10 +75,10 @@ Value QmlListWrapper::create(QV8Engine *v8, QObject *object, int propId, int pro
     r->propertyType = propType;
     void *args[] = { &r->property, 0 };
     QMetaObject::metacall(object, QMetaObject::ReadProperty, propId, args);
-    return Value::fromObject(r);
+    return Value::fromObject(r).asReturnedValue();
 }
 
-Value QmlListWrapper::create(QV8Engine *v8, const QQmlListProperty<QObject> &prop, int propType)
+ReturnedValue QmlListWrapper::create(QV8Engine *v8, const QQmlListProperty<QObject> &prop, int propType)
 {
     ExecutionEngine *v4 = QV8Engine::getV4(v8);
 
@@ -86,7 +86,7 @@ Value QmlListWrapper::create(QV8Engine *v8, const QQmlListProperty<QObject> &pro
     r->object = prop.object;
     r->property = prop;
     r->propertyType = propType;
-    return Value::fromObject(r);
+    return Value::fromObject(r).asReturnedValue();
 }
 
 QVariant QmlListWrapper::toVariant() const
@@ -126,7 +126,7 @@ ReturnedValue QmlListWrapper::getIndexed(Managed *m, uint index, bool *hasProper
 
     quint32 count = w->property.count ? w->property.count(&w->property) : 0;
     if (index < count && w->property.at)
-        return QV4::QObjectWrapper::wrap(e, w->property.at(&w->property, index)).asReturnedValue();
+        return QV4::QObjectWrapper::wrap(e, w->property.at(&w->property, index));
 
     return Value::undefinedValue().asReturnedValue();
 }
@@ -156,7 +156,7 @@ Property *QmlListWrapper::advanceIterator(Managed *m, ObjectIterator *it, String
             *attrs = QV4::Attr_Data;
         *index = it->arrayIndex;
         ++it->arrayIndex;
-        it->tmpDynamicProperty.value = QV4::QObjectWrapper::wrap(w->engine(), w->property.at(&w->property, *index));
+        it->tmpDynamicProperty.value = QV4::Value::fromReturnedValue(QV4::QObjectWrapper::wrap(w->engine(), w->property.at(&w->property, *index)));
         return &it->tmpDynamicProperty;
     }
     return QV4::Object::advanceIterator(m, it, name, index, attrs);
diff --git a/src/qml/qml/qqmllistwrapper_p.h b/src/qml/qml/qqmllistwrapper_p.h
index 4778443d6b..0de028a35b 100644
--- a/src/qml/qml/qqmllistwrapper_p.h
+++ b/src/qml/qml/qqmllistwrapper_p.h
@@ -76,8 +76,8 @@ protected:
 
 public:
 
-    static Value create(QV8Engine *v8, QObject *object, int propId, int propType);
-    static Value create(QV8Engine *v8, const QQmlListProperty<QObject> &prop, int propType);
+    static ReturnedValue create(QV8Engine *v8, QObject *object, int propId, int propType);
+    static ReturnedValue create(QV8Engine *v8, const QQmlListProperty<QObject> &prop, int propType);
 
     QVariant toVariant() const;
 
diff --git a/src/qml/qml/qqmllocale.cpp b/src/qml/qml/qqmllocale.cpp
index 27c8dff598..38ffc5386d 100644
--- a/src/qml/qml/qqmllocale.cpp
+++ b/src/qml/qml/qqmllocale.cpp
@@ -807,7 +807,7 @@ QQmlLocale::~QQmlLocale()
 {
 }
 
-QV4::Value QQmlLocale::locale(QV8Engine *v8engine, const QString &locale)
+QV4::ReturnedValue QQmlLocale::locale(QV8Engine *v8engine, const QString &locale)
 {
     QV8LocaleDataDeletable *d = localeV8Data(v8engine);
     QV4::ExecutionEngine *engine = QV8Engine::getV4(v8engine);
@@ -815,7 +815,7 @@ QV4::Value QQmlLocale::locale(QV8Engine *v8engine, const QString &locale)
     if (!locale.isEmpty())
         wrapper->locale = QLocale(locale);
     wrapper->setPrototype(d->prototype.value().asObject());
-    return QV4::Value::fromObject(wrapper);
+    return QV4::Value::fromObject(wrapper).asReturnedValue();
 }
 
 void QQmlLocale::registerStringLocaleCompare(QV4::ExecutionEngine *engine)
diff --git a/src/qml/qml/qqmllocale_p.h b/src/qml/qml/qqmllocale_p.h
index 5088693269..8075bd462f 100644
--- a/src/qml/qml/qqmllocale_p.h
+++ b/src/qml/qml/qqmllocale_p.h
@@ -118,7 +118,7 @@ public:
         Saturday = Qt::Saturday
     };
 
-    static QV4::Value locale(QV8Engine *v8engine, const QString &lang);
+    static QV4::ReturnedValue locale(QV8Engine *v8engine, const QString &lang);
 
     static void registerStringLocaleCompare(QV4::ExecutionEngine *engine);
 
diff --git a/src/qml/qml/qqmltypewrapper.cpp b/src/qml/qml/qqmltypewrapper.cpp
index 8f05a877ef..09ef732e2d 100644
--- a/src/qml/qml/qqmltypewrapper.cpp
+++ b/src/qml/qml/qqmltypewrapper.cpp
@@ -87,19 +87,19 @@ QVariant QmlTypeWrapper::toVariant() const
 
 
 // Returns a type wrapper for type t on o.  This allows access of enums, and attached properties.
-Value QmlTypeWrapper::create(QV8Engine *v8, QObject *o, QQmlType *t, TypeNameMode mode)
+ReturnedValue QmlTypeWrapper::create(QV8Engine *v8, QObject *o, QQmlType *t, TypeNameMode mode)
 {
     Q_ASSERT(t);
     ExecutionEngine *v4 = QV8Engine::getV4(v8);
 
     QmlTypeWrapper *w = new (v4->memoryManager) QmlTypeWrapper(v8);
     w->mode = mode; w->object = o; w->type = t;
-    return Value::fromObject(w);
+    return Value::fromObject(w).asReturnedValue();
 }
 
 // Returns a type wrapper for importNamespace (of t) on o.  This allows nested resolution of a type in a
 // namespace.
-Value QmlTypeWrapper::create(QV8Engine *v8, QObject *o, QQmlTypeNameCache *t, const void *importNamespace, TypeNameMode mode)
+ReturnedValue QmlTypeWrapper::create(QV8Engine *v8, QObject *o, QQmlTypeNameCache *t, const void *importNamespace, TypeNameMode mode)
 {
     Q_ASSERT(t);
     Q_ASSERT(importNamespace);
@@ -108,17 +108,20 @@ Value QmlTypeWrapper::create(QV8Engine *v8, QObject *o, QQmlTypeNameCache *t, co
     QmlTypeWrapper *w = new (v4->memoryManager) QmlTypeWrapper(v8);
     w->mode = mode; w->object = o; w->typeNamespace = t; w->importNamespace = importNamespace;
     t->addref();
-    return Value::fromObject(w);
+    return Value::fromObject(w).asReturnedValue();
 }
 
 
 ReturnedValue QmlTypeWrapper::get(Managed *m, String *name, bool *hasProperty)
 {
-    QmlTypeWrapper *w = m->as<QmlTypeWrapper>();
     QV4::ExecutionEngine *v4 = m->engine();
+    QV4::Scope scope(v4);
+
+    QmlTypeWrapper *w = m->as<QmlTypeWrapper>();
     if (!w)
         v4->current->throwTypeError();
 
+
     if (hasProperty)
         *hasProperty = true;
 
@@ -155,12 +158,12 @@ ReturnedValue QmlTypeWrapper::get(Managed *m, String *name, bool *hasProperty)
                 }
 
                 // check for property.
-                return QV4::QObjectWrapper::getQmlProperty(v4->current, context, qobjectSingleton, name, QV4::QObjectWrapper::IgnoreRevision, hasProperty).asReturnedValue();
+                return QV4::QObjectWrapper::getQmlProperty(v4->current, context, qobjectSingleton, name, QV4::QObjectWrapper::IgnoreRevision, hasProperty);
             } else if (!siinfo->scriptApi(e).isUndefined()) {
                 QV4::ExecutionEngine *engine = QV8Engine::getV4(v8engine);
                 // NOTE: if used in a binding, changes will not trigger re-evaluation since non-NOTIFYable.
-                QV4::Object *o = QJSValuePrivate::get(siinfo->scriptApi(e))->getValue(engine).asObject();
-                if (o)
+                QV4::Scoped<Object> o(scope, QJSValuePrivate::get(siinfo->scriptApi(e))->getValue(engine));
+                if (!!o)
                     return o->get(name);
             }
 
@@ -179,7 +182,7 @@ ReturnedValue QmlTypeWrapper::get(Managed *m, String *name, bool *hasProperty)
             } else if (w->object) {
                 QObject *ao = qmlAttachedPropertiesObjectById(type->attachedPropertiesId(), object);
                 if (ao)
-                    return QV4::QObjectWrapper::getQmlProperty(v4->current, context, ao, name, QV4::QObjectWrapper::IgnoreRevision, hasProperty).asReturnedValue();
+                    return QV4::QObjectWrapper::getQmlProperty(v4->current, context, ao, name, QV4::QObjectWrapper::IgnoreRevision, hasProperty);
 
                 // Fall through to base implementation
             }
@@ -196,16 +199,16 @@ ReturnedValue QmlTypeWrapper::get(Managed *m, String *name, bool *hasProperty)
         if (r.isValid()) {
             QQmlContextData *context = v8engine->callingContext();
             if (r.type) {
-                return create(w->v8, object, r.type, w->mode).asReturnedValue();
+                return create(w->v8, object, r.type, w->mode);
             } else if (r.scriptIndex != -1) {
                 int index = r.scriptIndex;
                 if (index < context->importedScripts.count())
                     return context->importedScripts.at(index).value().asReturnedValue();
             } else if (r.importNamespace) {
-                return create(w->v8, object, context->imports, r.importNamespace).asReturnedValue();
+                return create(w->v8, object, context->imports, r.importNamespace);
             }
 
-            return QV4::Value::undefinedValue().asReturnedValue();
+            return QV4::Encode::undefined();
 
         }
 
diff --git a/src/qml/qml/qqmltypewrapper_p.h b/src/qml/qml/qqmltypewrapper_p.h
index c545e1cc3b..acf6845736 100644
--- a/src/qml/qml/qqmltypewrapper_p.h
+++ b/src/qml/qml/qqmltypewrapper_p.h
@@ -78,8 +78,8 @@ public:
 
     QVariant toVariant() const;
 
-    static QV4::Value create(QV8Engine *, QObject *, QQmlType *, TypeNameMode = IncludeEnums);
-    static QV4::Value create(QV8Engine *, QObject *, QQmlTypeNameCache *, const void *, TypeNameMode = IncludeEnums);
+    static ReturnedValue create(QV8Engine *, QObject *, QQmlType *, TypeNameMode = IncludeEnums);
+    static ReturnedValue create(QV8Engine *, QObject *, QQmlTypeNameCache *, const void *, TypeNameMode = IncludeEnums);
 
 
     static ReturnedValue get(Managed *m, String *name, bool *hasProperty);
diff --git a/src/qml/qml/qqmlvaluetypewrapper.cpp b/src/qml/qml/qqmlvaluetypewrapper.cpp
index d9ee928858..88704d58b3 100644
--- a/src/qml/qml/qqmlvaluetypewrapper.cpp
+++ b/src/qml/qml/qqmlvaluetypewrapper.cpp
@@ -139,7 +139,7 @@ void QmlValueTypeWrapper::initProto(ExecutionEngine *v4)
     v4->qmlExtensions()->valueTypeWrapperPrototype = o;
 }
 
-Value QmlValueTypeWrapper::create(QV8Engine *v8, QObject *object, int property, QQmlValueType *type)
+ReturnedValue QmlValueTypeWrapper::create(QV8Engine *v8, QObject *object, int property, QQmlValueType *type)
 {
     ExecutionEngine *v4 = QV8Engine::getV4(v8);
     initProto(v4);
@@ -147,10 +147,10 @@ Value QmlValueTypeWrapper::create(QV8Engine *v8, QObject *object, int property,
     QmlValueTypeReference *r = new (v4->memoryManager) QmlValueTypeReference(v8);
     r->setPrototype(v4->qmlExtensions()->valueTypeWrapperPrototype);
     r->type = type; r->object = object; r->property = property;
-    return Value::fromObject(r);
+    return Value::fromObject(r).asReturnedValue();
 }
 
-Value QmlValueTypeWrapper::create(QV8Engine *v8, const QVariant &value, QQmlValueType *type)
+ReturnedValue QmlValueTypeWrapper::create(QV8Engine *v8, const QVariant &value, QQmlValueType *type)
 {
     ExecutionEngine *v4 = QV8Engine::getV4(v8);
     initProto(v4);
@@ -158,7 +158,7 @@ Value QmlValueTypeWrapper::create(QV8Engine *v8, const QVariant &value, QQmlValu
     QmlValueTypeCopy *r = new (v4->memoryManager) QmlValueTypeCopy(v8);
     r->setPrototype(v4->qmlExtensions()->valueTypeWrapperPrototype);
     r->type = type; r->value = value;
-    return Value::fromObject(r);
+    return Value::fromObject(r).asReturnedValue();
 }
 
 QVariant QmlValueTypeWrapper::toVariant() const
@@ -301,7 +301,7 @@ ReturnedValue QmlValueTypeWrapper::get(Managed *m, String *name, bool *hasProper
     if (result->isFunction()) {
         // calling a Q_INVOKABLE function of a value type
         QQmlContextData *qmlContext = QV4::QmlContextWrapper::callingContext(v4);
-        return QV4::QObjectWrapper::getQmlProperty(v4->current, qmlContext, r->type, name, QV4::QObjectWrapper::IgnoreRevision).asReturnedValue();
+        return QV4::QObjectWrapper::getQmlProperty(v4->current, qmlContext, r->type, name, QV4::QObjectWrapper::IgnoreRevision);
     }
 
 #define VALUE_TYPE_LOAD(metatype, cpptype, constructor) \
@@ -321,7 +321,7 @@ ReturnedValue QmlValueTypeWrapper::get(Managed *m, String *name, bool *hasProper
     QVariant v(result->propType, (void *)0);
     void *args[] = { v.data(), 0 };
     r->type->qt_metacall(QMetaObject::ReadProperty, result->coreIndex, args);
-    return r->v8->fromVariant(v).asReturnedValue();
+    return r->v8->fromVariant(v);
 #undef VALUE_TYPE_ACCESSOR
 }
 
diff --git a/src/qml/qml/qqmlvaluetypewrapper_p.h b/src/qml/qml/qqmlvaluetypewrapper_p.h
index 2483b8e26b..355000bb39 100644
--- a/src/qml/qml/qqmlvaluetypewrapper_p.h
+++ b/src/qml/qml/qqmlvaluetypewrapper_p.h
@@ -76,8 +76,8 @@ protected:
 
 public:
 
-    static Value create(QV8Engine *v8, QObject *, int, QQmlValueType *);
-    static Value create(QV8Engine *v8, const QVariant &, QQmlValueType *);
+    static ReturnedValue create(QV8Engine *v8, QObject *, int, QQmlValueType *);
+    static ReturnedValue create(QV8Engine *v8, const QVariant &, QQmlValueType *);
 
     QVariant toVariant() const;
     bool isEqual(const QVariant& value);
diff --git a/src/qml/qml/qqmlvme.cpp b/src/qml/qml/qqmlvme.cpp
index e32193e6f6..1a6577d7ad 100644
--- a/src/qml/qml/qqmlvme.cpp
+++ b/src/qml/qml/qqmlvme.cpp
@@ -372,7 +372,7 @@ QObject *QQmlVME::run(QList<QQmlError> *errors,
         // Store a created object in a property.  These all pop from the objects stack.
         QML_STORE_VALUE(StoreObject, QObject *, objects.pop());
         QML_STORE_VALUE(StoreVariantObject, QVariant, QVariant::fromValue(objects.pop()));
-        QML_STORE_VAR(StoreVarObject, QV4::QObjectWrapper::wrap(ep->v4engine(), objects.pop()));
+        QML_STORE_VAR(StoreVarObject, QV4::Value::fromReturnedValue(QV4::QObjectWrapper::wrap(ep->v4engine(), objects.pop())));
 
         // Store a literal value in a corresponding property
         QML_STORE_VALUE(StoreFloat, float, instr.value);
@@ -420,7 +420,7 @@ QObject *QQmlVME::run(QList<QQmlError> *errors,
 
         // Store a literal value in a var property.
         // We deliberately do not use string converters here
-        QML_STORE_VAR(StoreVar, ep->v8engine()->fromVariant(PRIMITIVES.at(instr.value)));
+        QML_STORE_VAR(StoreVar, QV4::Value::fromReturnedValue(ep->v8engine()->fromVariant(PRIMITIVES.at(instr.value))));
         QML_STORE_VAR(StoreVarInteger, QV4::Value::fromInt32(instr.value));
         QML_STORE_VAR(StoreVarDouble, QV4::Value::fromDouble(instr.value));
         QML_STORE_VAR(StoreVarBool, QV4::Value::fromBoolean(instr.value));
@@ -1113,6 +1113,8 @@ QV4::PersistentValue QQmlVME::run(QQmlContextData *parentCtxt, QQmlScriptData *s
     Q_ASSERT(parentCtxt && parentCtxt->engine);
     QQmlEnginePrivate *ep = QQmlEnginePrivate::get(parentCtxt->engine);
     QV8Engine *v8engine = ep->v8engine();
+    QV4::ExecutionEngine *v4 = QV8Engine::getV4(parentCtxt->engine);
+    QV4::Scope scope(v4);
 
     if (script->hasError()) {
         ep->warning(script->error());
@@ -1178,7 +1180,7 @@ QV4::PersistentValue QQmlVME::run(QQmlContextData *parentCtxt, QQmlScriptData *s
         return QV4::PersistentValue();
     }
 
-    QV4::Value qmlglobal = QV4::QmlContextWrapper::qmlScope(v8engine, ctxt, 0);
+    QV4::ScopedValue qmlglobal(scope, QV4::QmlContextWrapper::qmlScope(v8engine, ctxt, 0));
     QV4::QmlContextWrapper::takeContextOwnership(qmlglobal);
 
     QV4::ExecutionContext *ctx = QV8Engine::getV4(v8engine)->current;
diff --git a/src/qml/qml/qqmlvmemetaobject.cpp b/src/qml/qml/qqmlvmemetaobject.cpp
index 360528ea7a..488b4a0adf 100644
--- a/src/qml/qml/qqmlvmemetaobject.cpp
+++ b/src/qml/qml/qqmlvmemetaobject.cpp
@@ -911,8 +911,10 @@ int QQmlVMEMetaObject::metaCall(QMetaObject::Call c, int _id, void **a)
 
                 QQmlEnginePrivate *ep = QQmlEnginePrivate::get(ctxt->engine);
                 ep->referenceScarceResources(); // "hold" scarce resources in memory during evaluation.
+                QV4::Scope scope(ep->v4engine());
 
-                QV4::FunctionObject *function = method(id).asFunctionObject();
+
+                QV4::Scoped<QV4::FunctionObject> function(scope, method(id));
                 if (!function) {
                     // The function was not compiled.  There are some exceptional cases which the
                     // expression rewriter does not rewrite properly (e.g., \r-terminated lines
@@ -927,12 +929,11 @@ int QQmlVMEMetaObject::metaCall(QMetaObject::Call c, int _id, void **a)
 
                 QQmlVMEMetaData::MethodData *data = metaData->methodData() + id;
 
-                QV4::Scope scope(function->engine());
                 QV4::ScopedCallData callData(scope, data->parameterCount);
                 callData->thisObject = ep->v8engine()->global();
 
                 for (int ii = 0; ii < data->parameterCount; ++ii)
-                    callData->args[ii] = ep->v8engine()->fromVariant(*(QVariant *)a[ii + 1]);
+                    callData->args[ii] = QV4::Value::fromReturnedValue(ep->v8engine()->fromVariant(*(QVariant *)a[ii + 1]));
 
                 QV4::ScopedValue result(scope);
                 QV4::ExecutionContext *ctx = function->engine()->current;
@@ -961,11 +962,11 @@ int QQmlVMEMetaObject::metaCall(QMetaObject::Call c, int _id, void **a)
         return object->qt_metacall(c, _id, a);
 }
 
-QV4::Value QQmlVMEMetaObject::method(int index)
+QV4::ReturnedValue QQmlVMEMetaObject::method(int index)
 {
     if (!ctxt || !ctxt->isValid()) {
         qWarning("QQmlVMEMetaObject: Internal error - attempted to evaluate a function in an invalid context");
-        return QV4::Value::emptyValue();
+        return QV4::Value::emptyValue().asReturnedValue();
     }
 
     if (!v8methods) 
@@ -984,16 +985,16 @@ QV4::Value QQmlVMEMetaObject::method(int index)
                                                                ctxt->urlString, data->lineNumber);
     }
 
-    return v8methods[index];
+    return v8methods[index].value().asReturnedValue();
 }
 
-QV4::Value QQmlVMEMetaObject::readVarProperty(int id)
+QV4::ReturnedValue QQmlVMEMetaObject::readVarProperty(int id)
 {
     Q_ASSERT(id >= firstVarPropertyIndex);
 
     if (ensureVarPropertiesAllocated())
-        return QV4::Value::fromReturnedValue(varProperties.value().asObject()->getIndexed(id - firstVarPropertyIndex));
-    return QV4::Value::emptyValue();
+        return varProperties.value().asObject()->getIndexed(id - firstVarPropertyIndex);
+    return QV4::Value::emptyValue().asReturnedValue();
 }
 
 QVariant QQmlVMEMetaObject::readPropertyAsVariant(int id)
@@ -1070,8 +1071,8 @@ void QQmlVMEMetaObject::writeProperty(int id, const QVariant &value)
 
         // And, if the new value is a scarce resource, we need to ensure that it does not get
         // automatically released by the engine until no other references to it exist.
-        QV4::Value newv = QQmlEnginePrivate::get(ctxt->engine)->v8engine()->fromVariant(value);
-        if (QV4::VariantObject *v = newv.as<QV4::VariantObject>())
+        QV4::ScopedValue newv(scope, QQmlEnginePrivate::get(ctxt->engine)->v8engine()->fromVariant(value));
+        if (QV4::VariantObject *v = newv->as<QV4::VariantObject>())
             v->addVmePropertyReference();
 
         // Write the value and emit change signal as appropriate.
@@ -1150,7 +1151,7 @@ quint16 QQmlVMEMetaObject::vmeMethodLineNumber(int index)
     return data->lineNumber;
 }
 
-QV4::Value QQmlVMEMetaObject::vmeMethod(int index)
+QV4::ReturnedValue QQmlVMEMetaObject::vmeMethod(int index)
 {
     if (index < methodOffset()) {
         Q_ASSERT(parentVMEMetaObject());
@@ -1178,7 +1179,7 @@ void QQmlVMEMetaObject::setVmeMethod(int index, QV4::PersistentValue function)
     v8methods[methodIndex] = function;
 }
 
-QV4::Value QQmlVMEMetaObject::vmeProperty(int index)
+QV4::ReturnedValue QQmlVMEMetaObject::vmeProperty(int index)
 {
     if (index < propOffset()) {
         Q_ASSERT(parentVMEMetaObject());
diff --git a/src/qml/qml/qqmlvmemetaobject_p.h b/src/qml/qml/qqmlvmemetaobject_p.h
index 9824e0d54b..35592c4906 100644
--- a/src/qml/qml/qqmlvmemetaobject_p.h
+++ b/src/qml/qml/qqmlvmemetaobject_p.h
@@ -164,10 +164,10 @@ public:
 
     bool aliasTarget(int index, QObject **target, int *coreIndex, int *valueTypeIndex) const;
     void registerInterceptor(int index, int valueIndex, QQmlPropertyValueInterceptor *interceptor);
-    QV4::Value vmeMethod(int index);
+    QV4::ReturnedValue vmeMethod(int index);
     quint16 vmeMethodLineNumber(int index);
     void setVmeMethod(int index, QV4::PersistentValue function);
-    QV4::Value vmeProperty(int index);
+    QV4::ReturnedValue vmeProperty(int index);
     void setVMEProperty(int index, const QV4::Value &v);
 
     void connectAliasSignal(int index, bool indexInSignalRange);
@@ -217,9 +217,9 @@ public:
     QQmlPropertyValueInterceptor *interceptors;
 
     QV4::PersistentValue *v8methods;
-    QV4::Value method(int);
+    QV4::ReturnedValue method(int);
 
-    QV4::Value readVarProperty(int);
+    QV4::ReturnedValue readVarProperty(int);
     void writeVarProperty(int, const QV4::Value &);
     QVariant readPropertyAsVariant(int);
     void writeProperty(int, const QVariant &);
diff --git a/src/qml/qml/qqmlxmlhttprequest.cpp b/src/qml/qml/qqmlxmlhttprequest.cpp
index 651a2703f3..b7447aee07 100644
--- a/src/qml/qml/qqmlxmlhttprequest.cpp
+++ b/src/qml/qml/qqmlxmlhttprequest.cpp
@@ -100,9 +100,11 @@ static inline QQmlXMLHttpRequestData *xhrdata(QV8Engine *engine)
 static Value constructMeObject(const Value &thisObj, QV8Engine *e)
 {
     ExecutionEngine *v4 = QV8Engine::getV4(e);
+    Scope scope(v4);
     Object *meObj = v4->newObject();
     meObj->put(v4->newString(QStringLiteral("ThisObject")), thisObj);
-    meObj->put(v4->newString(QStringLiteral("ActivationObject")), QmlContextWrapper::qmlScope(e, e->callingContext(), 0));
+    ScopedValue v(scope, QmlContextWrapper::qmlScope(e, e->callingContext(), 0));
+    meObj->put(v4->newString(QStringLiteral("ActivationObject")), v);
     return Value::fromObject(meObj);
 }
 
diff --git a/src/qml/qml/v8/qqmlbuiltinfunctions.cpp b/src/qml/qml/v8/qqmlbuiltinfunctions.cpp
index 59457df30c..2a75bf9834 100644
--- a/src/qml/qml/v8/qqmlbuiltinfunctions.cpp
+++ b/src/qml/qml/v8/qqmlbuiltinfunctions.cpp
@@ -202,7 +202,7 @@ ReturnedValue QtObject::method_rgba(QV4::SimpleCallContext *ctx)
     if (a < 0.0) a=0.0;
     if (a > 1.0) a=1.0;
 
-    return ctx->engine->v8Engine->fromVariant(QQml_colorProvider()->fromRgbF(r, g, b, a)).asReturnedValue();
+    return ctx->engine->v8Engine->fromVariant(QQml_colorProvider()->fromRgbF(r, g, b, a));
 }
 
 /*!
@@ -231,7 +231,7 @@ ReturnedValue QtObject::method_hsla(QV4::SimpleCallContext *ctx)
     if (a < 0.0) a=0.0;
     if (a > 1.0) a=1.0;
 
-    return ctx->engine->v8Engine->fromVariant(QQml_colorProvider()->fromHslF(h, s, l, a)).asReturnedValue();
+    return ctx->engine->v8Engine->fromVariant(QQml_colorProvider()->fromHslF(h, s, l, a));
 }
 
 /*!
@@ -292,7 +292,7 @@ ReturnedValue QtObject::method_rect(QV4::SimpleCallContext *ctx)
     double w = ctx->arguments[2].toNumber();
     double h = ctx->arguments[3].toNumber();
 
-    return ctx->engine->v8Engine->fromVariant(QVariant::fromValue(QRectF(x, y, w, h))).asReturnedValue();
+    return ctx->engine->v8Engine->fromVariant(QVariant::fromValue(QRectF(x, y, w, h)));
 }
 
 /*!
@@ -307,7 +307,7 @@ ReturnedValue QtObject::method_point(QV4::SimpleCallContext *ctx)
     double x = ctx->arguments[0].toNumber();
     double y = ctx->arguments[1].toNumber();
 
-    return ctx->engine->v8Engine->fromVariant(QVariant::fromValue(QPointF(x, y))).asReturnedValue();
+    return ctx->engine->v8Engine->fromVariant(QVariant::fromValue(QPointF(x, y)));
 }
 
 /*!
@@ -322,7 +322,7 @@ ReturnedValue QtObject::method_size(QV4::SimpleCallContext *ctx)
     double w = ctx->arguments[0].toNumber();
     double h = ctx->arguments[1].toNumber();
 
-    return ctx->engine->v8Engine->fromVariant(QVariant::fromValue(QSizeF(w, h))).asReturnedValue();
+    return ctx->engine->v8Engine->fromVariant(QVariant::fromValue(QSizeF(w, h)));
 }
 
 /*!
@@ -343,7 +343,7 @@ ReturnedValue QtObject::method_font(QV4::SimpleCallContext *ctx)
     QVariant v = QQml_valueTypeProvider()->createVariantFromJsObject(QMetaType::QFont, QQmlV4Handle(ctx->arguments[0]), v8engine, &ok);
     if (!ok)
         V4THROW_ERROR("Qt.font(): Invalid argument: no valid font subproperties specified");
-    return v8engine->fromVariant(v).asReturnedValue();
+    return v8engine->fromVariant(v);
 }
 
 
@@ -363,7 +363,7 @@ ReturnedValue QtObject::method_vector2d(QV4::SimpleCallContext *ctx)
 
     const void *params[] = { xy };
     QV8Engine *v8engine = ctx->engine->v8Engine;
-    return v8engine->fromVariant(QQml_valueTypeProvider()->createValueType(QMetaType::QVector2D, 1, params)).asReturnedValue();
+    return v8engine->fromVariant(QQml_valueTypeProvider()->createValueType(QMetaType::QVector2D, 1, params));
 }
 
 /*!
@@ -382,7 +382,7 @@ ReturnedValue QtObject::method_vector3d(QV4::SimpleCallContext *ctx)
 
     const void *params[] = { xyz };
     QV8Engine *v8engine = ctx->engine->v8Engine;
-    return v8engine->fromVariant(QQml_valueTypeProvider()->createValueType(QMetaType::QVector3D, 1, params)).asReturnedValue();
+    return v8engine->fromVariant(QQml_valueTypeProvider()->createValueType(QMetaType::QVector3D, 1, params));
 }
 
 /*!
@@ -402,7 +402,7 @@ ReturnedValue QtObject::method_vector4d(QV4::SimpleCallContext *ctx)
 
     const void *params[] = { xyzw };
     QV8Engine *v8engine = ctx->engine->v8Engine;
-    return v8engine->fromVariant(QQml_valueTypeProvider()->createValueType(QMetaType::QVector4D, 1, params)).asReturnedValue();
+    return v8engine->fromVariant(QQml_valueTypeProvider()->createValueType(QMetaType::QVector4D, 1, params));
 }
 
 /*!
@@ -422,7 +422,7 @@ ReturnedValue QtObject::method_quaternion(QV4::SimpleCallContext *ctx)
 
     const void *params[] = { sxyz };
     QV8Engine *v8engine = ctx->engine->v8Engine;
-    return v8engine->fromVariant(QQml_valueTypeProvider()->createValueType(QMetaType::QQuaternion, 1, params)).asReturnedValue();
+    return v8engine->fromVariant(QQml_valueTypeProvider()->createValueType(QMetaType::QQuaternion, 1, params));
 }
 
 /*!
@@ -441,7 +441,7 @@ ReturnedValue QtObject::method_matrix4x4(QV4::SimpleCallContext *ctx)
         QVariant v = QQml_valueTypeProvider()->createVariantFromJsObject(QMetaType::QMatrix4x4, QQmlV4Handle(ctx->arguments[0]), v8engine, &ok);
         if (!ok)
             V4THROW_ERROR("Qt.matrix4x4(): Invalid argument: not a valid matrix4x4 values array");
-        return v8engine->fromVariant(v).asReturnedValue();
+        return v8engine->fromVariant(v);
     }
 
     if (ctx->argumentCount != 16)
@@ -466,7 +466,7 @@ ReturnedValue QtObject::method_matrix4x4(QV4::SimpleCallContext *ctx)
     vals[15] = ctx->arguments[15].toNumber();
 
     const void *params[] = { vals };
-    return v8engine->fromVariant(QQml_valueTypeProvider()->createValueType(QMetaType::QMatrix4x4, 1, params)).asReturnedValue();
+    return v8engine->fromVariant(QQml_valueTypeProvider()->createValueType(QMetaType::QMatrix4x4, 1, params));
 }
 
 /*!
@@ -504,7 +504,7 @@ ReturnedValue QtObject::method_lighter(QV4::SimpleCallContext *ctx)
     if (ctx->argumentCount == 2)
         factor = ctx->arguments[1].toNumber();
 
-    return v8engine->fromVariant(QQml_colorProvider()->lighter(v, factor)).asReturnedValue();
+    return v8engine->fromVariant(QQml_colorProvider()->lighter(v, factor));
 }
 
 /*!
@@ -543,7 +543,7 @@ ReturnedValue QtObject::method_darker(QV4::SimpleCallContext *ctx)
     if (ctx->argumentCount == 2)
         factor = ctx->arguments[1].toNumber();
 
-    return v8engine->fromVariant(QQml_colorProvider()->darker(v, factor)).asReturnedValue();
+    return v8engine->fromVariant(QQml_colorProvider()->darker(v, factor));
 }
 
 /*!
@@ -601,7 +601,7 @@ ReturnedValue QtObject::method_tint(QV4::SimpleCallContext *ctx)
         return QV4::Encode::null();
     }
 
-    return v8engine->fromVariant(QQml_colorProvider()->tint(v1, v2)).asReturnedValue();
+    return v8engine->fromVariant(QQml_colorProvider()->tint(v1, v2));
 }
 
 /*!
@@ -645,7 +645,7 @@ ReturnedValue QtObject::method_formatDate(QV4::SimpleCallContext *ctx)
          formattedDate = date.toString(enumFormat);
     }
 
-    return v8engine->fromVariant(QVariant::fromValue(formattedDate)).asReturnedValue();
+    return v8engine->fromVariant(QVariant::fromValue(formattedDate));
 }
 
 /*!
@@ -694,7 +694,7 @@ ReturnedValue QtObject::method_formatTime(QV4::SimpleCallContext *ctx)
          formattedTime = time.toString(enumFormat);
     }
 
-    return v8engine->fromVariant(QVariant::fromValue(formattedTime)).asReturnedValue();
+    return v8engine->fromVariant(QVariant::fromValue(formattedTime));
 }
 
 /*!
@@ -812,7 +812,7 @@ ReturnedValue QtObject::method_formatDateTime(QV4::SimpleCallContext *ctx)
          formattedDt = dt.toString(enumFormat);
     }
 
-    return v8engine->fromVariant(QVariant::fromValue(formattedDt)).asReturnedValue();
+    return v8engine->fromVariant(QVariant::fromValue(formattedDt));
 }
 
 /*!
@@ -827,7 +827,7 @@ ReturnedValue QtObject::method_openUrlExternally(QV4::SimpleCallContext *ctx)
     QV8Engine *v8engine = ctx->engine->v8Engine;
 
     QUrl url(Value::fromReturnedValue(method_resolvedUrl(ctx)).toQStringNoThrow());
-    return v8engine->fromVariant(QQml_guiProvider()->openUrlExternally(url)).asReturnedValue();
+    return v8engine->fromVariant(QQml_guiProvider()->openUrlExternally(url));
 }
 
 /*!
@@ -863,7 +863,7 @@ ReturnedValue QtObject::method_fontFamilies(SimpleCallContext *ctx)
         V4THROW_ERROR("Qt.fontFamilies(): Invalid arguments");
 
     QV8Engine *v8engine = ctx->engine->v8Engine;
-    return v8engine->fromVariant(QVariant(QQml_guiProvider()->fontFamilies())).asReturnedValue();
+    return v8engine->fromVariant(QVariant(QQml_guiProvider()->fontFamilies()));
 }
 
 /*!
@@ -1039,7 +1039,7 @@ ReturnedValue QtObject::method_createQmlObject(SimpleCallContext *ctx)
 
     Q_ASSERT(obj);
 
-    return QV4::QObjectWrapper::wrap(ctx->engine, obj).asReturnedValue();
+    return QV4::QObjectWrapper::wrap(ctx->engine, obj);
 }
 
 /*!
@@ -1133,7 +1133,7 @@ ReturnedValue QtObject::method_createComponent(SimpleCallContext *ctx)
     QQmlData::get(c, true)->explicitIndestructibleSet = false;
     QQmlData::get(c)->indestructible = false;
 
-    return QV4::QObjectWrapper::wrap(ctx->engine, c).asReturnedValue();
+    return QV4::QObjectWrapper::wrap(ctx->engine, c);
 }
 
 /*!
@@ -1168,7 +1168,7 @@ ReturnedValue QtObject::method_locale(SimpleCallContext *ctx)
     if (ctx->argumentCount == 1)
         code = ctx->arguments[0].toQStringNoThrow();
 
-    return QQmlLocale::locale(v8engine, code).asReturnedValue();
+    return QQmlLocale::locale(v8engine, code);
 }
 
 namespace {
@@ -1276,7 +1276,7 @@ ReturnedValue QtObject::method_get_platform(SimpleCallContext *ctx)
         // Only allocate a platform object once
         qt->m_platform = new QQmlPlatform(ctx->engine->v8Engine->publicEngine());
 
-    return QV4::QObjectWrapper::wrap(ctx->engine, qt->m_platform).asReturnedValue();
+    return QV4::QObjectWrapper::wrap(ctx->engine, qt->m_platform);
 }
 
 ReturnedValue QtObject::method_get_application(SimpleCallContext *ctx)
@@ -1293,7 +1293,7 @@ ReturnedValue QtObject::method_get_application(SimpleCallContext *ctx)
         // Only allocate an application object once
         qt->m_application = QQml_guiProvider()->application(ctx->engine->v8Engine->publicEngine());
 
-    return QV4::QObjectWrapper::wrap(ctx->engine, qt->m_application).asReturnedValue();
+    return QV4::QObjectWrapper::wrap(ctx->engine, qt->m_application);
 }
 
 #ifndef QT_NO_IM
@@ -1301,7 +1301,7 @@ ReturnedValue QtObject::method_get_inputMethod(SimpleCallContext *ctx)
 {
     QObject *o = QQml_guiProvider()->inputMethod();
     QQmlEngine::setObjectOwnership(o, QQmlEngine::CppOwnership);
-    return QV4::QObjectWrapper::wrap(ctx->engine, o).asReturnedValue();
+    return QV4::QObjectWrapper::wrap(ctx->engine, o);
 }
 #endif
 
diff --git a/src/qml/qml/v8/qv8engine.cpp b/src/qml/qml/v8/qv8engine.cpp
index c377608341..63ab33a457 100644
--- a/src/qml/qml/v8/qv8engine.cpp
+++ b/src/qml/qml/v8/qv8engine.cpp
@@ -181,7 +181,7 @@ QVariant QV8Engine::toVariant(const QV4::Value &value, int typeHint)
     return toBasicVariant(value);
 }
 
-static QV4::Value arrayFromStringList(QV8Engine *engine, const QStringList &list)
+static QV4::ReturnedValue arrayFromStringList(QV8Engine *engine, const QStringList &list)
 {
     QV4::ExecutionEngine *e = QV8Engine::getV4(engine);
     QV4::ArrayObject *a = e->newArrayObject();
@@ -191,10 +191,10 @@ static QV4::Value arrayFromStringList(QV8Engine *engine, const QStringList &list
     for (int ii = 0; ii < len; ++ii)
         a->arrayData[ii].value = QV4::Value::fromString(e->newString(list.at(ii)));
     a->setArrayLengthUnchecked(len);
-    return QV4::Value::fromObject(a);
+    return QV4::Value::fromObject(a).asReturnedValue();
 }
 
-static QV4::Value arrayFromVariantList(QV8Engine *engine, const QVariantList &list)
+static QV4::ReturnedValue arrayFromVariantList(QV8Engine *engine, const QVariantList &list)
 {
     QV4::ExecutionEngine *e = QV8Engine::getV4(engine);
     QV4::ArrayObject *a = e->newArrayObject();
@@ -202,23 +202,23 @@ static QV4::Value arrayFromVariantList(QV8Engine *engine, const QVariantList &li
     a->arrayReserve(len);
     a->arrayDataLen = len;
     for (int ii = 0; ii < len; ++ii)
-        a->arrayData[ii].value = engine->fromVariant(list.at(ii));
+        a->arrayData[ii].value = QV4::Value::fromReturnedValue(engine->fromVariant(list.at(ii)));
     a->setArrayLengthUnchecked(len);
-    return QV4::Value::fromObject(a);
+    return QV4::Value::fromObject(a).asReturnedValue();
 }
 
-static QV4::Value objectFromVariantMap(QV8Engine *engine, const QVariantMap &map)
+static QV4::ReturnedValue objectFromVariantMap(QV8Engine *engine, const QVariantMap &map)
 {
     QV4::ExecutionEngine *e = QV8Engine::getV4(engine);
     QV4::Object *o = e->newObject();
     for (QVariantMap::ConstIterator iter = map.begin(); iter != map.end(); ++iter)
-        o->put(e->newString(iter.key()), engine->fromVariant(iter.value()));
-    return QV4::Value::fromObject(o);
+        o->put(e->newString(iter.key()), QV4::Value::fromReturnedValue(engine->fromVariant(iter.value())));
+    return QV4::Value::fromObject(o).asReturnedValue();
 }
 
 Q_CORE_EXPORT QString qt_regexp_toCanonical(const QString &, QRegExp::PatternSyntax);
 
-QV4::Value QV8Engine::fromVariant(const QVariant &variant)
+QV4::ReturnedValue QV8Engine::fromVariant(const QVariant &variant)
 {
     int type = variant.userType();
     const void *ptr = variant.constData();
@@ -227,49 +227,50 @@ QV4::Value QV8Engine::fromVariant(const QVariant &variant)
         switch (QMetaType::Type(type)) {
             case QMetaType::UnknownType:
             case QMetaType::Void:
-                return QV4::Value::undefinedValue();
+                return QV4::Encode::undefined();
             case QMetaType::Bool:
-                return QV4::Value::fromBoolean(*reinterpret_cast<const bool*>(ptr));
+                return QV4::Encode(*reinterpret_cast<const bool*>(ptr));
             case QMetaType::Int:
-                return QV4::Value::fromInt32(*reinterpret_cast<const int*>(ptr));
+                return QV4::Encode(*reinterpret_cast<const int*>(ptr));
             case QMetaType::UInt:
-                return QV4::Value::fromUInt32(*reinterpret_cast<const uint*>(ptr));
+                return QV4::Encode(*reinterpret_cast<const uint*>(ptr));
             case QMetaType::LongLong:
-                return QV4::Value::fromDouble(*reinterpret_cast<const qlonglong*>(ptr));
+                return QV4::Encode((double)*reinterpret_cast<const qlonglong*>(ptr));
             case QMetaType::ULongLong:
-                return QV4::Value::fromDouble(*reinterpret_cast<const qulonglong*>(ptr));
+                return QV4::Encode((double)*reinterpret_cast<const qulonglong*>(ptr));
             case QMetaType::Double:
-                return QV4::Value::fromDouble(*reinterpret_cast<const double*>(ptr));
+                return QV4::Encode(*reinterpret_cast<const double*>(ptr));
             case QMetaType::QString:
-                return QV4::Value::fromString(m_v4Engine->current, *reinterpret_cast<const QString*>(ptr));
+                return QV4::Value::fromString(m_v4Engine->current, *reinterpret_cast<const QString*>(ptr)).asReturnedValue();
             case QMetaType::Float:
-                return QV4::Value::fromDouble(*reinterpret_cast<const float*>(ptr));
+                return QV4::Encode(*reinterpret_cast<const float*>(ptr));
             case QMetaType::Short:
-                return QV4::Value::fromInt32(*reinterpret_cast<const short*>(ptr));
+                return QV4::Encode((int)*reinterpret_cast<const short*>(ptr));
             case QMetaType::UShort:
-                return QV4::Value::fromUInt32(*reinterpret_cast<const unsigned short*>(ptr));
+                return QV4::Encode((int)*reinterpret_cast<const unsigned short*>(ptr));
             case QMetaType::Char:
-                return QV4::Value::fromInt32(*reinterpret_cast<const char*>(ptr));
+                return QV4::Encode((int)*reinterpret_cast<const char*>(ptr));
             case QMetaType::UChar:
-                return QV4::Value::fromUInt32(*reinterpret_cast<const unsigned char*>(ptr));
+                return QV4::Encode((int)*reinterpret_cast<const unsigned char*>(ptr));
             case QMetaType::QChar:
-                return QV4::Value::fromInt32((*reinterpret_cast<const QChar*>(ptr)).unicode());
+                return QV4::Encode((int)(*reinterpret_cast<const QChar*>(ptr)).unicode());
             case QMetaType::QDateTime:
-                return QV4::Value::fromObject(m_v4Engine->newDateObject(*reinterpret_cast<const QDateTime *>(ptr)));
+                return QV4::Value::fromObject(m_v4Engine->newDateObject(*reinterpret_cast<const QDateTime *>(ptr))).asReturnedValue();
             case QMetaType::QDate:
-                return QV4::Value::fromObject(m_v4Engine->newDateObject(QDateTime(*reinterpret_cast<const QDate *>(ptr))));
+                return QV4::Value::fromObject(m_v4Engine->newDateObject(QDateTime(*reinterpret_cast<const QDate *>(ptr)))).asReturnedValue();
             case QMetaType::QTime:
-            return QV4::Value::fromObject(m_v4Engine->newDateObject(QDateTime(QDate(1970,1,1), *reinterpret_cast<const QTime *>(ptr))));
+            return QV4::Value::fromObject(m_v4Engine->newDateObject(QDateTime(QDate(1970,1,1), *reinterpret_cast<const QTime *>(ptr)))).asReturnedValue();
             case QMetaType::QRegExp:
-                return QV4::Value::fromObject(m_v4Engine->newRegExpObject(*reinterpret_cast<const QRegExp *>(ptr)));
+                return QV4::Value::fromObject(m_v4Engine->newRegExpObject(*reinterpret_cast<const QRegExp *>(ptr))).asReturnedValue();
             case QMetaType::QObjectStar:
                 return QV4::QObjectWrapper::wrap(m_v4Engine, *reinterpret_cast<QObject* const *>(ptr));
             case QMetaType::QStringList:
                 {
                 bool succeeded = false;
-                QV4::Value retn = QV4::SequencePrototype::fromVariant(m_v4Engine, variant, &succeeded);
+                QV4::Scope scope(m_v4Engine);
+                QV4::ScopedValue retn(scope, QV4::SequencePrototype::fromVariant(m_v4Engine, variant, &succeeded));
                 if (succeeded)
-                    return retn;
+                    return retn.asReturnedValue();
                 return arrayFromStringList(this, *reinterpret_cast<const QStringList *>(ptr));
                 }
             case QMetaType::QVariantList:
@@ -290,13 +291,14 @@ QV4::Value QV8Engine::fromVariant(const QVariant &variant)
         if (QQmlValueType *vt = QQmlValueTypeFactory::valueType(type))
             return QV4::QmlValueTypeWrapper::create(this, variant, vt);
     } else {
+        QV4::Scope scope(m_v4Engine);
         if (type == qMetaTypeId<QQmlListReference>()) {
             typedef QQmlListReferencePrivate QDLRP;
             QDLRP *p = QDLRP::get((QQmlListReference*)ptr);
             if (p->object) {
                 return QV4::QmlListWrapper::create(this, p->property, p->propertyType);
             } else {
-                return QV4::Value::nullValue();
+                return QV4::Encode::null();
             }
         } else if (type == qMetaTypeId<QJSValue>()) {
             const QJSValue *value = reinterpret_cast<const QJSValue *>(ptr);
@@ -310,9 +312,9 @@ QV4::Value QV8Engine::fromVariant(const QVariant &variant)
             a->arrayReserve(list.count());
             a->arrayDataLen = list.count();
             for (int ii = 0; ii < list.count(); ++ii)
-                a->arrayData[ii].value = QV4::QObjectWrapper::wrap(m_v4Engine, list.at(ii));
+                a->arrayData[ii].value = QV4::Value::fromReturnedValue(QV4::QObjectWrapper::wrap(m_v4Engine, list.at(ii)));
             a->setArrayLengthUnchecked(list.count());
-            return QV4::Value::fromObject(a);
+            return QV4::Value::fromObject(a).asReturnedValue();
         } else if (QMetaType::typeFlags(type) & QMetaType::PointerToQObject) {
             return QV4::QObjectWrapper::wrap(m_v4Engine, *reinterpret_cast<QObject* const *>(ptr));
         }
@@ -323,9 +325,9 @@ QV4::Value QV8Engine::fromVariant(const QVariant &variant)
             return QV4::QObjectWrapper::wrap(m_v4Engine, obj);
 
         bool succeeded = false;
-        QV4::Value retn = QV4::SequencePrototype::fromVariant(m_v4Engine, variant, &succeeded);
+        QV4::ScopedValue retn(scope, QV4::SequencePrototype::fromVariant(m_v4Engine, variant, &succeeded));
         if (succeeded)
-            return retn;
+            return retn.asReturnedValue();
 
         if (QQmlValueType *vt = QQmlValueTypeFactory::valueType(type))
             return QV4::QmlValueTypeWrapper::create(this, variant, vt);
@@ -335,7 +337,7 @@ QV4::Value QV8Engine::fromVariant(const QVariant &variant)
     //    + QObjectList
     //    + QList<int>
 
-    return QV4::Value::fromObject(m_v4Engine->newVariantObject(variant));
+    return QV4::Value::fromObject(m_v4Engine->newVariantObject(variant)).asReturnedValue();
 }
 
 QNetworkAccessManager *QV8Engine::networkAccessManager()
@@ -513,15 +515,15 @@ QV4::Value QV8Engine::global()
 // The result is a new Array object with length equal to the length
 // of the QVariantList, and the elements being the QVariantList's
 // elements converted to JS, recursively.
-QV4::Value QV8Engine::variantListToJS(const QVariantList &lst)
+QV4::ReturnedValue QV8Engine::variantListToJS(const QVariantList &lst)
 {
     QV4::ArrayObject *a = m_v4Engine->newArrayObject();
     a->arrayReserve(lst.size());
     a->arrayDataLen = lst.size();
     for (int i = 0; i < lst.size(); i++)
-        a->arrayData[i].value = variantToJS(lst.at(i));
+        a->arrayData[i].value = QV4::Value::fromReturnedValue(variantToJS(lst.at(i)));
     a->setArrayLengthUnchecked(lst.size());
-    return QV4::Value::fromObject(a);
+    return QV4::Value::fromObject(a).asReturnedValue();
 }
 
 // Converts a JS Array object to a QVariantList.
@@ -559,15 +561,15 @@ QVariantList QV8Engine::variantListFromJS(QV4::ArrayObject *a,
 // The result is a new Object object with property names being
 // the keys of the QVariantMap, and values being the values of
 // the QVariantMap converted to JS, recursively.
-QV4::Value QV8Engine::variantMapToJS(const QVariantMap &vmap)
+QV4::ReturnedValue QV8Engine::variantMapToJS(const QVariantMap &vmap)
 {
     QV4::Object *o = 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 = variantToJS(it.value());
+        p->value = QV4::Value::fromReturnedValue(variantToJS(it.value()));
     }
-    return QV4::Value::fromObject(o);
+    return QV4::Value::fromObject(o).asReturnedValue();
 }
 
 // Converts a JS Object to a QVariantMap.
@@ -588,17 +590,19 @@ QVariantMap QV8Engine::variantMapFromJS(QV4::Object *o,
         // empty object (and no error is thrown).
         return result;
     }
+    QV4::Scope scope(o->engine());
 
     visitedObjects.insert(o);
 
     QV4::ObjectIterator it(o, QV4::ObjectIterator::EnumerableOnly);
+    QV4::ScopedValue name(scope);
     while (1) {
         QV4::Value v;
-        QV4::Value name = it.nextPropertyNameAsString(&v);
-        if (name.isNull())
+        name = it.nextPropertyNameAsString(&v);
+        if (name->isNull())
             break;
 
-        QString key = name.toQStringNoThrow();
+        QString key = name->toQStringNoThrow();
         result.insert(key, variantFromJS(v, visitedObjects));
     }
 
@@ -608,96 +612,85 @@ QVariantMap QV8Engine::variantMapFromJS(QV4::Object *o,
 
 // Converts the meta-type defined by the given type and data to JS.
 // Returns the value if conversion succeeded, an empty handle otherwise.
-QV4::Value QV8Engine::metaTypeToJS(int type, const void *data)
+QV4::ReturnedValue QV8Engine::metaTypeToJS(int type, const void *data)
 {
     Q_ASSERT(data != 0);
-    QV4::Value result;
 
     // check if it's one of the types we know
     switch (QMetaType::Type(type)) {
     case QMetaType::UnknownType:
     case QMetaType::Void:
-        return QV4::Value::undefinedValue();
+        return QV4::Encode::undefined();
     case QMetaType::Bool:
-        return QV4::Value::fromBoolean(*reinterpret_cast<const bool*>(data));
+        return QV4::Encode(*reinterpret_cast<const bool*>(data));
     case QMetaType::Int:
-        return QV4::Value::fromInt32(*reinterpret_cast<const int*>(data));
+        return QV4::Encode(*reinterpret_cast<const int*>(data));
     case QMetaType::UInt:
-        return QV4::Value::fromUInt32(*reinterpret_cast<const uint*>(data));
+        return QV4::Encode(*reinterpret_cast<const uint*>(data));
     case QMetaType::LongLong:
-        return QV4::Value::fromDouble(double(*reinterpret_cast<const qlonglong*>(data)));
+        return QV4::Encode(double(*reinterpret_cast<const qlonglong*>(data)));
     case QMetaType::ULongLong:
 #if defined(Q_OS_WIN) && defined(_MSC_FULL_VER) && _MSC_FULL_VER <= 12008804
 #pragma message("** NOTE: You need the Visual Studio Processor Pack to compile support for 64bit unsigned integers.")
-        return QV4::Value::fromDouble(double((qlonglong)*reinterpret_cast<const qulonglong*>(data)));
+        return QV4::Encode(double((qlonglong)*reinterpret_cast<const qulonglong*>(data)));
 #elif defined(Q_CC_MSVC) && !defined(Q_CC_MSVC_NET)
-        return QV4::Value::fromDouble(double((qlonglong)*reinterpret_cast<const qulonglong*>(data)));
+        return QV4::Encode(double((qlonglong)*reinterpret_cast<const qulonglong*>(data)));
 #else
-        return QV4::Value::fromDouble(double(*reinterpret_cast<const qulonglong*>(data)));
+        return QV4::Encode(double(*reinterpret_cast<const qulonglong*>(data)));
 #endif
     case QMetaType::Double:
-        return QV4::Value::fromDouble(*reinterpret_cast<const double*>(data));
+        return QV4::Encode(*reinterpret_cast<const double*>(data));
     case QMetaType::QString:
-        return QV4::Value::fromString(m_v4Engine->current, *reinterpret_cast<const QString*>(data));
+        return QV4::Value::fromString(m_v4Engine->current, *reinterpret_cast<const QString*>(data)).asReturnedValue();
     case QMetaType::Float:
-        return QV4::Value::fromDouble(*reinterpret_cast<const float*>(data));
+        return QV4::Encode(*reinterpret_cast<const float*>(data));
     case QMetaType::Short:
-        return QV4::Value::fromInt32(*reinterpret_cast<const short*>(data));
+        return QV4::Encode((int)*reinterpret_cast<const short*>(data));
     case QMetaType::UShort:
-        return QV4::Value::fromUInt32(*reinterpret_cast<const unsigned short*>(data));
+        return QV4::Encode((int)*reinterpret_cast<const unsigned short*>(data));
     case QMetaType::Char:
-        return QV4::Value::fromInt32(*reinterpret_cast<const char*>(data));
+        return QV4::Encode((int)*reinterpret_cast<const char*>(data));
     case QMetaType::UChar:
-        return QV4::Value::fromUInt32(*reinterpret_cast<const unsigned char*>(data));
+        return QV4::Encode((int)*reinterpret_cast<const unsigned char*>(data));
     case QMetaType::QChar:
-        return QV4::Value::fromUInt32((*reinterpret_cast<const QChar*>(data)).unicode());
+        return QV4::Encode((int)(*reinterpret_cast<const QChar*>(data)).unicode());
     case QMetaType::QStringList:
-        result = QV4::Value::fromObject(m_v4Engine->newArrayObject(*reinterpret_cast<const QStringList *>(data)));
-        break;
+        return QV4::Value::fromObject(m_v4Engine->newArrayObject(*reinterpret_cast<const QStringList *>(data))).asReturnedValue();
     case QMetaType::QVariantList:
-        result = variantListToJS(*reinterpret_cast<const QVariantList *>(data));
-        break;
+        return variantListToJS(*reinterpret_cast<const QVariantList *>(data));
     case QMetaType::QVariantMap:
-        result = variantMapToJS(*reinterpret_cast<const QVariantMap *>(data));
-        break;
+        return variantMapToJS(*reinterpret_cast<const QVariantMap *>(data));
     case QMetaType::QDateTime:
-        result = QV4::Value::fromObject(m_v4Engine->newDateObject(*reinterpret_cast<const QDateTime *>(data)));
-        break;
+        return QV4::Value::fromObject(m_v4Engine->newDateObject(*reinterpret_cast<const QDateTime *>(data))).asReturnedValue();
     case QMetaType::QDate:
-        result = QV4::Value::fromObject(m_v4Engine->newDateObject(QDateTime(*reinterpret_cast<const QDate *>(data))));
-        break;
+        return QV4::Value::fromObject(m_v4Engine->newDateObject(QDateTime(*reinterpret_cast<const QDate *>(data)))).asReturnedValue();
     case QMetaType::QRegExp:
-        result = QV4::Value::fromObject(m_v4Engine->newRegExpObject(*reinterpret_cast<const QRegExp *>(data)));
-        break;
+        return QV4::Value::fromObject(m_v4Engine->newRegExpObject(*reinterpret_cast<const QRegExp *>(data))).asReturnedValue();
     case QMetaType::QObjectStar:
-        result = QV4::QObjectWrapper::wrap(m_v4Engine, *reinterpret_cast<QObject* const *>(data));
-        break;
+        return QV4::QObjectWrapper::wrap(m_v4Engine, *reinterpret_cast<QObject* const *>(data));
     case QMetaType::QVariant:
-        result = variantToJS(*reinterpret_cast<const QVariant*>(data));
-        break;
+        return variantToJS(*reinterpret_cast<const QVariant*>(data));
     case QMetaType::QJsonValue:
-        result = QV4::JsonObject::fromJsonValue(m_v4Engine, *reinterpret_cast<const QJsonValue *>(data));
-        break;
+        return QV4::JsonObject::fromJsonValue(m_v4Engine, *reinterpret_cast<const QJsonValue *>(data));
     case QMetaType::QJsonObject:
-        result = QV4::JsonObject::fromJsonObject(m_v4Engine, *reinterpret_cast<const QJsonObject *>(data));
-        break;
+        return QV4::JsonObject::fromJsonObject(m_v4Engine, *reinterpret_cast<const QJsonObject *>(data));
     case QMetaType::QJsonArray:
-        result = QV4::JsonObject::fromJsonArray(m_v4Engine, *reinterpret_cast<const QJsonArray *>(data));
-        break;
+        return QV4::JsonObject::fromJsonArray(m_v4Engine, *reinterpret_cast<const QJsonArray *>(data));
     default:
         if (type == qMetaTypeId<QJSValue>()) {
             return QJSValuePrivate::get(*reinterpret_cast<const QJSValue*>(data))->getValue(m_v4Engine);
         } else {
             QByteArray typeName = QMetaType::typeName(type);
             if (typeName.endsWith('*') && !*reinterpret_cast<void* const *>(data)) {
-                return QV4::Value::nullValue();
+                return QV4::Encode::null();
             } else {
                 // Fall back to wrapping in a QVariant.
-                result = QV4::Value::fromObject(m_v4Engine->newVariantObject(QVariant(type, data)));
+                return QV4::Value::fromObject(m_v4Engine->newVariantObject(QVariant(type, data))).asReturnedValue();
             }
         }
     }
-    return result;
+    Q_UNREACHABLE();
+    return 0;
 }
 
 // Converts a JS value to a meta-type.
@@ -874,7 +867,7 @@ bool QV8Engine::metaTypeFromJS(const QV4::Value &value, int type, void *data) {
 }
 
 // Converts a QVariant to JS.
-QV4::Value QV8Engine::variantToJS(const QVariant &value)
+QV4::ReturnedValue QV8Engine::variantToJS(const QVariant &value)
 {
     return metaTypeToJS(value.userType(), value.constData());
 }
diff --git a/src/qml/qml/v8/qv8engine_p.h b/src/qml/qml/v8/qv8engine_p.h
index 1296973394..3209e55434 100644
--- a/src/qml/qml/v8/qv8engine_p.h
+++ b/src/qml/qml/v8/qv8engine_p.h
@@ -121,6 +121,7 @@ namespace QV4 {
 // valid during the call.  If the return value isn't set within myMethod(), the will return
 // undefined.
 class QV8Engine;
+// ### GC
 class QQmlV4Function
 {
 public:
@@ -129,6 +130,7 @@ public:
     QQmlContextData *context() { return ctx; }
     QV4::Value qmlGlobal() { return global; }
     void setReturnValue(const QV4::Value &rv) { *retVal = rv; }
+    void setReturnValue(QV4::ReturnedValue rv) { *retVal = QV4::Value::fromReturnedValue(rv); }
     QV8Engine *engine() const { return e; }
 private:
     friend struct QV4::QObjectMethod;
@@ -149,6 +151,7 @@ private:
     QV8Engine *e;
 };
 
+// ### GC
 class Q_QML_PRIVATE_EXPORT QQmlV4Handle
 {
 public:
@@ -210,7 +213,7 @@ public:
     void freezeObject(const QV4::Value &value);
 
     QVariant toVariant(const QV4::Value &value, int typeHint);
-    QV4::Value fromVariant(const QVariant &);
+    QV4::ReturnedValue fromVariant(const QVariant &);
 
     // Return a JS string for the given QString \a string
     QV4::Value toString(const QString &string);
@@ -232,19 +235,19 @@ public:
     inline Deletable *extensionData(int) const;
     void setExtensionData(int, Deletable *);
 
-    QV4::Value variantListToJS(const QVariantList &lst);
+    QV4::ReturnedValue variantListToJS(const QVariantList &lst);
     inline QVariantList variantListFromJS(QV4::ArrayObject *array)
     { V8ObjectSet visitedObjects; return variantListFromJS(array, visitedObjects); }
 
-    QV4::Value variantMapToJS(const QVariantMap &vmap);
+    QV4::ReturnedValue variantMapToJS(const QVariantMap &vmap);
     inline QVariantMap variantMapFromJS(QV4::Object *object)
     { V8ObjectSet visitedObjects; return variantMapFromJS(object, visitedObjects); }
 
-    QV4::Value variantToJS(const QVariant &value);
+    QV4::ReturnedValue variantToJS(const QVariant &value);
     inline QVariant variantFromJS(const QV4::Value &value)
     { V8ObjectSet visitedObjects; return variantFromJS(value, visitedObjects); }
 
-    QV4::Value metaTypeToJS(int type, const void *data);
+    QV4::ReturnedValue metaTypeToJS(int type, const void *data);
     bool metaTypeFromJS(const QV4::Value &value, int type, void *data);
 
     bool convertToNativeQObject(const QV4::Value &value,