Fix QQml_setParent_noEvent not to print undefined behavior errors

When building Qt with -fsanitize undefined, the usage of
QQml_setParent_noEvent caused the following error message:
"qqmlglobal_p.h:233:5: runtime error: downcast of address
0x60300061bf10 which does not point to an object of type
'QQmlGraphics_DerivedObject'".

Instead of casting to the referred type, use QObjectPrivate::get to
access the d_ptr.

Change-Id: I2f2224bdb20a8d2e35a3291961378231f03c4ba2
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

2 files changed, 10 insertions, 22 deletions

diff --git a/src/qml/qml/qqmlglobal_p.h b/src/qml/qml/qqmlglobal_p.h
index a6c113f5a7..5c46da0ea4 100644
--- a/src/qml/qml/qqmlglobal_p.h
+++ b/src/qml/qml/qqmlglobal_p.h
@@ -193,16 +193,6 @@ do { \
     return QObjectPrivate::get(sender)->isSignalConnected(signalIdx); \
 } while (0)
 
-struct QQmlGraphics_DerivedObject : public QObject
-{
-    void setParent_noEvent(QObject *parent) {
-        bool sce = d_ptr->sendChildEvents;
-        d_ptr->sendChildEvents = false;
-        setParent(parent);
-        d_ptr->sendChildEvents = sce;
-    }
-};
-
 /*!
     Returns true if the case of \a fileName is equivalent to the file case of
     \a fileName on disk, and false otherwise.
@@ -230,7 +220,11 @@ bool QQml_isFileCaseCorrect(const QString &fileName, int length = -1);
 */
 inline void QQml_setParent_noEvent(QObject *object, QObject *parent)
 {
-    static_cast<QQmlGraphics_DerivedObject *>(object)->setParent_noEvent(parent);
+    QObjectPrivate *d_ptr = QObjectPrivate::get(object);
+    bool sce = d_ptr->sendChildEvents;
+    d_ptr->sendChildEvents = false;
+    object->setParent(parent);
+    d_ptr->sendChildEvents = sce;
 }
 
 class Q_QML_PRIVATE_EXPORT QQmlValueTypeProvider
diff --git a/tests/benchmarks/qml/creation/tst_creation.cpp b/tests/benchmarks/qml/creation/tst_creation.cpp
index 91f907ab5e..ed2e52f869 100644
--- a/tests/benchmarks/qml/creation/tst_creation.cpp
+++ b/tests/benchmarks/qml/creation/tst_creation.cpp
@@ -204,19 +204,13 @@ void tst_creation::qobject_qmltype()
     }
 }
 
-struct QQmlGraphics_Derived : public QObject
-{
-    void setParent_noEvent(QObject *parent) {
-        bool sce = d_ptr->sendChildEvents;
-        d_ptr->sendChildEvents = false;
-        setParent(parent);
-        d_ptr->sendChildEvents = sce;
-    }
-};
-
 inline void QQmlGraphics_setParent_noEvent(QObject *object, QObject *parent)
 {
-    static_cast<QQmlGraphics_Derived *>(object)->setParent_noEvent(parent);
+    QObjectPrivate *d_ptr = QObjectPrivate::get(object);
+    bool sce = d_ptr->sendChildEvents;
+    d_ptr->sendChildEvents = false;
+    object->setParent(parent);
+    d_ptr->sendChildEvents = sce;
 }
 
 void tst_creation::itemtree_notree_cpp()