tst_QApplication: Fix UBs (invalid cast) in focusMouseClick()

Found by UBSan:

  tst_qapplication.cpp:1754:48: runtime error: member access within address 0x7ffda11f2220 which does not point to an object of type 'SpontaneousEvent'
  0x7ffda11f2220: note: object is of type 'QMouseEvent'

The code attempted to model the layout of a QEvent with another class
that allows public access to the memory location that (hopefully)
corresponds to QEvent::spont, gaining access by casting a QEvent
object to that specifically-crafted class.

Fix by the using the existing QSpontaneKeyEvent::setSpontaneous()
call, which, despite its name, works for all QEvent subclasses, and
which has already been fixed to not invoke UB (in bc087db).

Change-Id: I7db8b8a8a823f7d61ab17375142d19dc3874fea5
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

1 files changed, 3 insertions, 22 deletions

diff --git a/tests/auto/widgets/kernel/qapplication/tst_qapplication.cpp b/tests/auto/widgets/kernel/qapplication/tst_qapplication.cpp
index 878136b4a0..87a189fc87 100644
--- a/tests/auto/widgets/kernel/qapplication/tst_qapplication.cpp
+++ b/tests/auto/widgets/kernel/qapplication/tst_qapplication.cpp
@@ -1769,25 +1769,6 @@ void tst_QApplication::focusOut()
     QTest::qWait(2000);
 }
 
-class SpontaneousEvent
-{
-    Q_GADGET
-    QDOC_PROPERTY(bool accepted READ isAccepted WRITE setAccepted)
-    Q_ENUMS(Type)
-public:
-    enum Type {
-        Void
-    };
-
-    virtual ~SpontaneousEvent() {}
-
-    QEventPrivate *d;
-    ushort t;
-
-    ushort posted : 1;
-    ushort spont : 1;
-};
-
 void tst_QApplication::focusMouseClick()
 {
     int argc = 1;
@@ -1805,14 +1786,14 @@ void tst_QApplication::focusMouseClick()
     // now send a mouse button press event and check what happens with the focus
     // it should be given to the parent widget
     QMouseEvent ev(QEvent::MouseButtonPress, QPointF(), Qt::LeftButton, Qt::LeftButton, Qt::NoModifier);
-    reinterpret_cast<SpontaneousEvent *>(&ev)->spont = 1;
+    QSpontaneKeyEvent::setSpontaneous(&ev);
     QVERIFY(ev.spontaneous());
     qApp->notify(&w2, &ev);
     QCOMPARE(QApplication::focusWidget(), &w);
 
     // then we give the inner widget strong focus -> it should get focus
     w2.setFocusPolicy(Qt::StrongFocus);
-    reinterpret_cast<SpontaneousEvent *>(&ev)->spont = 1;
+    QSpontaneKeyEvent::setSpontaneous(&ev);
     QVERIFY(ev.spontaneous());
     qApp->notify(&w2, &ev);
     QTRY_COMPARE(QApplication::focusWidget(), &w2);
@@ -1820,7 +1801,7 @@ void tst_QApplication::focusMouseClick()
     // now back to tab focus and click again (it already had focus) -> focus should stay
     // (focus was revoked as of QTBUG-34042)
     w2.setFocusPolicy(Qt::TabFocus);
-    reinterpret_cast<SpontaneousEvent *>(&ev)->spont = 1;
+    QSpontaneKeyEvent::setSpontaneous(&ev);
     QVERIFY(ev.spontaneous());
     qApp->notify(&w2, &ev);
     QCOMPARE(QApplication::focusWidget(), &w2);