From c514812aaffd5c652db0c8972ee8327607df5927 Mon Sep 17 00:00:00 2001
From: Laszlo Agocs <laszlo.agocs@qt.io>
Date: Fri, 1 Jul 2022 15:20:08 +0200
Subject: [PATCH] Be more graceful when objects die by the time the dnd loop
 exits

The main issue fixed in 7f23dd963536eb8123ee4c5c22bf43b6f866d008 can
manifest in another form on platforms where QBasicDrag is used (xcb).

Make sure that we recognize if an object (e.g. a QWidgetWindow) is
destroyed by the time the nested event loop exits.

Task-number: QTBUG-104596
Change-Id: Ib82dd8230cb6f13d804bd992234b2a3ce85a7061
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>
(cherry picked from commit 742ae9ea1cadbb438e2d02bb58ae900c676dc41c)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
---
 src/gui/kernel/qsimpledrag.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/gui/kernel/qsimpledrag.cpp b/src/gui/kernel/qsimpledrag.cpp
index a88955b99a9..71cf3f04397 100644
--- a/src/gui/kernel/qsimpledrag.cpp
+++ b/src/gui/kernel/qsimpledrag.cpp
@@ -124,6 +124,7 @@ bool QBasicDrag::eventFilter(QObject *o, QEvent *e)
         }
         case QEvent::MouseButtonRelease:
         {
+            QPointer<QObject> objGuard(o);
             disableEventFilter();
             if (canDrop()) {
                 QPoint nativePosition = getNativeMousePos(e, m_drag_icon_window);
@@ -133,6 +134,8 @@ bool QBasicDrag::eventFilter(QObject *o, QEvent *e)
                 cancel();
             }
             exitDndEventLoop();
+            if (!objGuard)
+                return true;
 
             // If a QShapedPixmapWindow (drag feedback) is being dragged along, the
             // mouse event's localPos() will be relative to that, which is useless.