We guard QWidgetWindow's widget with a QPointer to avoid
sending it events during destruction (which may result in
undefined behavior, since this originates from ~QObject and
we expect the object to behave as a QWidget). Therefore, we
need to harden all access to that widget since it can now
be null, specially during destruction.
As an example, QGestureManager may crash when we delete a
top-level widget. The crash stack trace is:
1 QScopedPointer<QObjectData, QScopedPointerDeleter<QObjectData>>::data() const
2 QScopedPointer<QObjectData, QScopedPointerDeleter<QObjectData>>::pointer qGetPtrHelper<QScopedPointer<QObjectData, QScopedPointerDeleter<QObjectData>>>(QScopedPointer<QObjectData, QScopedPointerDeleter<QObjectData>> const&)
3 QWidget::d_func()
4 QGestureManager::filterEvent(QWidget *, QEvent *) <-- the widget ptr is null
5 QGestureManager::filterEvent(QObject *, QEvent *)
6 QApplication::notify(QObject *, QEvent *)
7 QCoreApplication::notifyInternal2(QObject *, QEvent *)
8 QCoreApplication::sendEvent(QObject *, QEvent *)
9 QWindow::destroy()
10 QWidgetPrivate::deleteTLSysExtra()
11 QWidgetPrivate::deleteExtra()
12 QWidgetPrivate::~QWidgetPrivate()
13 QWidgetPrivate::~QWidgetPrivate()
14 QWidgetPrivate::~QWidgetPrivate()
15 QScopedPointerDeleter<QObjectData>::cleanup(QObjectData *)
16 QScopedPointer<QObjectData, QScopedPointerDeleter<QObjectData>>::~QScopedPointer()
17 QScopedPointer<QObjectData, QScopedPointerDeleter<QObjectData>>::~QScopedPointer()
18 QObject::~QObject()
19 QWidget::~QWidget()
Task-number: QTBUG-53103
Change-Id: I1bb32648270c4f7791f668b8f0b639ddb4235703
Reviewed-by: Shawn Rutledge <shawn.rutledge@theqtcompany.com>
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
ce37467acf