Allow the existence of a VME metaobject to be asserted

Test for the existence of a VME metaobject.  Otherwise, assertion of
a static cast result is not meaningful.

Change-Id: Ic9e9c38e5dce65c41d20e405c33e179334c37b00
Reviewed-by: Michael Brasser <michael.brasser@nokia.com>
Reviewed-by: Chris Adams <christopher.adams@nokia.com>

8 files changed, 39 insertions, 15 deletions

diff --git a/src/qml/debugger/qqmlenginedebugservice.cpp b/src/qml/debugger/qqmlenginedebugservice.cpp
index f948c048e8..068bc36ebc 100644
--- a/src/qml/debugger/qqmlenginedebugservice.cpp
+++ b/src/qml/debugger/qqmlenginedebugservice.cpp
@@ -721,8 +721,7 @@ bool QQmlEngineDebugService::setMethodBody(int objectId, const QString &method,
     jsfunction += body;
     jsfunction += QLatin1String("\n})");
 
-    QQmlVMEMetaObject *vmeMetaObject =
-            static_cast<QQmlVMEMetaObject*>(QObjectPrivate::get(object)->metaObject);
+    QQmlVMEMetaObject *vmeMetaObject = QQmlVMEMetaObject::get(object);
     Q_ASSERT(vmeMetaObject); // the fact we found the property above should guarentee this
 
     int lineNumber = vmeMetaObject->vmeMethodLineNumber(prop->coreIndex);
diff --git a/src/qml/qml/qqmldata_p.h b/src/qml/qml/qqmldata_p.h
index 6547e19f3e..eba2f4df6e 100644
--- a/src/qml/qml/qqmldata_p.h
+++ b/src/qml/qml/qqmldata_p.h
@@ -79,7 +79,8 @@ class Q_QML_PRIVATE_EXPORT QQmlData : public QAbstractDeclarativeData
 public:
     QQmlData()
         : ownMemory(true), ownContext(false), indestructible(true), explicitIndestructibleSet(false), 
-          hasTaintedV8Object(false), isQueuedForDeletion(false), rootObjectInCreation(false), notifyList(0), context(0), outerContext(0),
+          hasTaintedV8Object(false), isQueuedForDeletion(false), rootObjectInCreation(false),
+          hasVMEMetaObject(false), notifyList(0), context(0), outerContext(0),
           bindings(0), signalHandlers(0), nextContextObject(0), prevContextObject(0), bindingBitsSize(0), bindingBits(0),
           lineNumber(0), columnNumber(0), compiledData(0), deferredIdx(0), v8objectid(0),
           propertyCache(0), guards(0), extendedData(0) {
@@ -120,7 +121,8 @@ public:
      * v8 GC will check this flag, only deletes the objects when rootObjectInCreation is false.
      */
     quint32 rootObjectInCreation:1;
-    quint32 dummy:25;
+    quint32 hasVMEMetaObject:1;
+    quint32 dummy:24;
 
     struct NotifyList {
         quint64 connectionMask;
diff --git a/src/qml/qml/qqmlproperty.cpp b/src/qml/qml/qqmlproperty.cpp
index 224d6a6bd5..d68d8a9517 100644
--- a/src/qml/qml/qqmlproperty.cpp
+++ b/src/qml/qml/qqmlproperty.cpp
@@ -1496,7 +1496,6 @@ bool QQmlPropertyPrivate::writeBinding(QObject *object,
     if (expression->hasError()) {
         return false;
     } else if (isVmeProperty) {
-        typedef QQmlVMEMetaObject VMEMO;
         if (!result.IsEmpty() && result->IsFunction()
                 && !result->ToObject()->GetHiddenValue(v8engine->bindingFlagKey()).IsEmpty()) {
             // we explicitly disallow this case to avoid confusion.  Users can still store one
@@ -1504,7 +1503,8 @@ bool QQmlPropertyPrivate::writeBinding(QObject *object,
             expression->delayedError()->error.setDescription(QLatin1String("Invalid use of Qt.binding() in a binding declaration."));
             return false;
         }
-        VMEMO *vmemo = static_cast<VMEMO *>(const_cast<QMetaObject *>(object->metaObject()));
+        QQmlVMEMetaObject *vmemo = QQmlVMEMetaObject::get(object);
+        Q_ASSERT(vmemo);
         vmemo->setVMEProperty(core.coreIndex, result);
     } else if (isUndefined && core.isResettable()) {
         void *args[] = { 0 };
diff --git a/src/qml/qml/qqmlvme.cpp b/src/qml/qml/qqmlvme.cpp
index ba0f202bcc..08ab49493d 100644
--- a/src/qml/qml/qqmlvme.cpp
+++ b/src/qml/qml/qqmlvme.cpp
@@ -298,8 +298,8 @@ static QVariant variantFromString(const QString &string)
         v8::Handle<v8::Value> v8value = value; \
         QObject *target = objects.top(); \
         CLEAN_PROPERTY(target, instr.propertyIndex); \
-        QMetaObject *mo = const_cast<QMetaObject *>(target->metaObject()); \
-        QQmlVMEMetaObject *vmemo = static_cast<QQmlVMEMetaObject *>(mo); \
+        QQmlVMEMetaObject *vmemo = QQmlVMEMetaObject::get(target); \
+        Q_ASSERT(vmemo); \
         vmemo->setVMEProperty(instr.propertyIndex, v8value); \
     QML_END_INSTR(name)
 
@@ -920,7 +920,8 @@ QObject *QQmlVME::run(QList<QQmlError> *errors,
                 QQmlPropertyPrivate::restore(target, instr.property, CTXT);
             obj->setParent(target);
             vi->setTarget(prop);
-            QQmlVMEMetaObject *mo = static_cast<QQmlVMEMetaObject *>((QMetaObject*)target->metaObject());
+            QQmlVMEMetaObject *mo = QQmlVMEMetaObject::get(target);
+            Q_ASSERT(mo);
             mo->registerInterceptor(prop.index(), QQmlPropertyPrivate::valueTypeCoreIndex(prop), vi);
         QML_END_INSTR(StoreValueInterceptor)
 
diff --git a/src/qml/qml/qqmlvmemetaobject.cpp b/src/qml/qml/qqmlvmemetaobject.cpp
index 4d531b392c..77a0482edf 100644
--- a/src/qml/qml/qqmlvmemetaobject.cpp
+++ b/src/qml/qml/qqmlvmemetaobject.cpp
@@ -493,6 +493,7 @@ QQmlVMEMetaObject::QQmlVMEMetaObject(QObject *obj, const QMetaObject *other, con
     if (op->metaObject)
         parent = static_cast<QAbstractDynamicMetaObject*>(op->metaObject);
     op->metaObject = this;
+    QQmlData::get(obj)->hasVMEMetaObject = true;
 
     propOffset = QAbstractDynamicMetaObject::propertyOffset();
     methodOffset = QAbstractDynamicMetaObject::methodOffset();
diff --git a/src/qml/qml/qqmlvmemetaobject_p.h b/src/qml/qml/qqmlvmemetaobject_p.h
index 1f44c63a47..c9992471d4 100644
--- a/src/qml/qml/qqmlvmemetaobject_p.h
+++ b/src/qml/qml/qqmlvmemetaobject_p.h
@@ -169,6 +169,8 @@ public:
 
     void connectAliasSignal(int index);
 
+    static inline QQmlVMEMetaObject *get(const QObject *obj);
+
 protected:
     virtual int metaCall(QMetaObject::Call _c, int _id, void **_a);
 
@@ -227,6 +229,18 @@ private:
     friend class QV8QObjectWrapper;
 };
 
+QQmlVMEMetaObject *QQmlVMEMetaObject::get(const QObject *obj)
+{
+    if (obj) {
+        if (QQmlData *data = QQmlData::get(obj)) {
+            if (data->hasVMEMetaObject)
+                return const_cast<QQmlVMEMetaObject *>(static_cast<const QQmlVMEMetaObject *>(obj->metaObject()));
+        }
+    }
+
+    return 0;
+}
+
 QT_END_NAMESPACE
 
 #endif // QQMLVMEMETAOBJECT_P_H
diff --git a/src/qml/qml/v4/qv4bindings.cpp b/src/qml/qml/v4/qv4bindings.cpp
index 6ab1e00b5c..f25bfccce4 100644
--- a/src/qml/qml/v4/qv4bindings.cpp
+++ b/src/qml/qml/v4/qv4bindings.cpp
@@ -1949,7 +1949,8 @@ void QV4Bindings::run(int instrIndex, quint32 &executedBlocks,
 
         if (data.gettype() == V8HandleType) {
             // This property must be a VME var property
-            QQmlVMEMetaObject *vmemo = static_cast<QQmlVMEMetaObject *>(const_cast<QMetaObject *>(output->metaObject()));
+            QQmlVMEMetaObject *vmemo = QQmlVMEMetaObject::get(output);
+            Q_ASSERT(vmemo);
             vmemo->setVMEProperty(instr->store.index, *data.gethandleptr());
         } else {
             int status = -1;
diff --git a/src/qml/qml/v8/qv8qobjectwrapper.cpp b/src/qml/qml/v8/qv8qobjectwrapper.cpp
index 15d7b1fca8..95e2be7584 100644
--- a/src/qml/qml/v8/qv8qobjectwrapper.cpp
+++ b/src/qml/qml/v8/qv8qobjectwrapper.cpp
@@ -533,7 +533,9 @@ v8::Handle<v8::Value> QV8QObjectWrapper::GetProperty(QV8Engine *engine, QObject
 
     if (result->isFunction() && !result->isVMEProperty()) {
         if (result->isVMEFunction()) {
-            return ((QQmlVMEMetaObject *)(object->metaObject()))->vmeMethod(result->coreIndex);
+            QQmlVMEMetaObject *vmemo = QQmlVMEMetaObject::get(object);
+            Q_ASSERT(vmemo);
+            return vmemo->vmeMethod(result->coreIndex);
         } else if (result->isV8Function()) {
             return MethodClosure::createWithGlobal(engine, object, objectHandle, result->coreIndex);
         } else if (result->isSignalHandler()) {
@@ -571,8 +573,8 @@ v8::Handle<v8::Value> QV8QObjectWrapper::GetProperty(QV8Engine *engine, QObject
         ep->captureProperty(object, result->coreIndex, result->notifyIndex);
 
     if (result->isVMEProperty()) {
-        typedef QQmlVMEMetaObject VMEMO;
-        VMEMO *vmemo = const_cast<VMEMO *>(static_cast<const VMEMO *>(object->metaObject()));
+        QQmlVMEMetaObject *vmemo = QQmlVMEMetaObject::get(object);
+        Q_ASSERT(vmemo);
         return vmemo->vmeProperty(result->coreIndex);
     } else if (result->isDirect())  {
         return LoadProperty<ReadAccessor::Direct>(engine, object, *result, 0);
@@ -622,7 +624,9 @@ static inline void StoreProperty(QV8Engine *engine, QObject *object, QQmlPropert
 
     if (!newBinding && property->isVMEProperty()) {
         // allow assignment of "special" values (null, undefined, function) to var properties
-        static_cast<QQmlVMEMetaObject *>(const_cast<QMetaObject *>(object->metaObject()))->setVMEProperty(property->coreIndex, value);
+        QQmlVMEMetaObject *vmemo = QQmlVMEMetaObject::get(object);
+        Q_ASSERT(vmemo);
+        vmemo->setVMEProperty(property->coreIndex, value);
         return;
     }
 
@@ -660,7 +664,9 @@ static inline void StoreProperty(QV8Engine *engine, QObject *object, QQmlPropert
     } else if (property->propType == QMetaType::QString && value->IsString()) {
         PROPERTY_STORE(QString, engine->toString(value->ToString()));
     } else if (property->isVMEProperty()) {
-        static_cast<QQmlVMEMetaObject *>(const_cast<QMetaObject *>(object->metaObject()))->setVMEProperty(property->coreIndex, value);
+        QQmlVMEMetaObject *vmemo = QQmlVMEMetaObject::get(object);
+        Q_ASSERT(vmemo);
+        vmemo->setVMEProperty(property->coreIndex, value);
     } else {
         QVariant v;
         if (property->isQList())