Warn, don't crash during nested delivery of mouse or touch presses

If during delivery of a mouse press, user code calls qApp->sendEvent()
with another mouse press, then when delivery of the nested event is
finished, we call QQuickPointerMouseEvent::reset(nullptr).  Then when
delivery of the original mouse press resumes, crashes are possible
because most of the code assumes that QQuickPointerEvent::m_event is
not null during delivery.

Change-Id: Id65b1f2f64351e40d03bcd4f4d16693d616729da
Fixes: QTBUG-70898
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

1 files changed, 2 insertions, 0 deletions

diff --git a/src/quick/items/qquickevents_p_p.h b/src/quick/items/qquickevents_p_p.h
index 4097845ec9..b2642735f2 100644
--- a/src/quick/items/qquickevents_p_p.h
+++ b/src/quick/items/qquickevents_p_p.h
@@ -447,6 +447,8 @@ protected:
     Qt::MouseButton m_button = Qt::NoButton;
     Qt::MouseButtons m_pressedButtons;
 
+    friend class QQuickWindowPrivate;
+
     Q_DISABLE_COPY(QQuickPointerEvent)
 };