From 8ef83e60df0291ba2a36cc744e1f0c11f465f1e2 Mon Sep 17 00:00:00 2001
From: Gabriel de Dietrich <gabriel.dietrich-de@nokia.com>
Date: Thu, 15 Oct 2009 18:45:13 +0200
Subject: Fixed a rare crash in qt_x11_enforce_cursor

A QPointer was set to point to a QWidget by one of its children, during its
deletion. This happens during the child deletion, and after the call to
QObject::clearGuards(), which means that the QPointer becomes a dangling one.

The fix ensures that qt_x11_enforce_cursor will not be called with a
being-deleted QWidget. The included auto-test doesn't test anything, except
that it doesn't crash.

Reviewed-by: Olivier
---
 src/gui/kernel/qapplication.cpp    |  5 ++++-
 tests/auto/qwidget/tst_qwidget.cpp | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/src/gui/kernel/qapplication.cpp b/src/gui/kernel/qapplication.cpp
index b990fe2..5476e36 100644
--- a/src/gui/kernel/qapplication.cpp
+++ b/src/gui/kernel/qapplication.cpp
@@ -2662,7 +2662,10 @@ void QApplicationPrivate::dispatchEnterLeave(QWidget* enter, QWidget* leave) {
         if (!isAlien(w))
             break;
         if (w->testAttribute(Qt::WA_SetCursor)) {
-            parentOfLeavingCursor = w->parentWidget();
+            QWidget *parent = w->parentWidget();
+            while (parent && parent->d_func()->data.in_destructor)
+                parent = parent->parentWidget();
+            parentOfLeavingCursor = parent;
             //continue looping, we need to find the downest alien widget with a cursor.
             // (downest on the screen)
         }
diff --git a/tests/auto/qwidget/tst_qwidget.cpp b/tests/auto/qwidget/tst_qwidget.cpp
index daeee3d..4cb9f72 100644
--- a/tests/auto/qwidget/tst_qwidget.cpp
+++ b/tests/auto/qwidget/tst_qwidget.cpp
@@ -69,6 +69,9 @@
 #include <QtGui/qpaintengine.h>
 #include <private/qbackingstore_p.h>
 
+#include <QtGui/QGraphicsView>
+#include <QtGui/QGraphicsProxyWidget>
+
 #include "../../shared/util.h"
 
 
@@ -285,6 +288,7 @@ private slots:
 #ifdef Q_WS_X11
     void minAndMaxSizeWithX11BypassWindowManagerHint();
     void showHideShow();
+    void clean_qt_x11_enforce_cursor();
 #endif
 
     void compatibilityChildInsertedEvents();
@@ -6048,6 +6052,35 @@ void tst_QWidget::showHideShow()
 
     QVERIFY(w.gotExpectedMapNotify);
 }
+
+void tst_QWidget::clean_qt_x11_enforce_cursor()
+{
+    {
+        QWidget window;
+        QWidget *w = new QWidget(&window);
+        QWidget *child = new QWidget(w);
+        child->setAttribute(Qt::WA_SetCursor, true);
+
+        window.show();
+        QApplication::setActiveWindow(&window);
+        QTest::qWaitForWindowShown(&window);
+        QTest::qWait(100);
+        QCursor::setPos(window.geometry().center());
+        QTest::qWait(100);
+
+        child->setFocus();
+        QApplication::processEvents();
+        QTest::qWait(100);
+
+        delete w;
+    }
+
+    QGraphicsScene scene;
+    QLineEdit *edit = new QLineEdit;
+    scene.addWidget(edit);
+
+    // If the test didn't crash, then it passed.
+}
 #endif
 
 class EventRecorder : public QObject
-- 
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