avoid possible crash when showing a modal dialog from a widget destructor

Task-number: QTBUG-5804
Reviewed-by: denis

2 files changed, 28 insertions, 2 deletions

diff --git a/src/gui/kernel/qwidget.cpp b/src/gui/kernel/qwidget.cpp
index 709f6f3..fbb9115 100644
--- a/src/gui/kernel/qwidget.cpp
+++ b/src/gui/kernel/qwidget.cpp
@@ -8248,7 +8248,8 @@ bool QWidget::event(QEvent *event)
             QList<QObject*> childList = d->children;
             for (int i = 0; i < childList.size(); ++i) {
                 QObject *o = childList.at(i);
-                QApplication::sendEvent(o, event);
+                if (o)
+                    QApplication::sendEvent(o, event);
             }
         }
         update();
@@ -8277,7 +8278,7 @@ bool QWidget::event(QEvent *event)
             QList<QObject*> childList = d->children;
             for (int i = 0; i < childList.size(); ++i) {
                 QObject *o = childList.at(i);
-                if (o != QApplication::activeModalWidget()) {
+                if (o && o != QApplication::activeModalWidget()) {
                     if (qobject_cast<QWidget *>(o) && static_cast<QWidget *>(o)->isWindow()) {
                         // do not forward the event to child windows,
                         // QApplication does this for us
diff --git a/tests/auto/qwidget/tst_qwidget.cpp b/tests/auto/qwidget/tst_qwidget.cpp
index 9692c6e..1e3f5f8 100644
--- a/tests/auto/qwidget/tst_qwidget.cpp
+++ b/tests/auto/qwidget/tst_qwidget.cpp
@@ -384,6 +384,8 @@ private slots:
 
     void activateWindow();
 
+    void openModal_taskQTBUG_5804();
+
 #ifdef Q_OS_SYMBIAN
     void cbaVisibility();
 #endif
@@ -9583,6 +9585,29 @@ void tst_QWidget::activateWindow()
     QTRY_VERIFY(!mainwindow2->isActiveWindow());
 }
 
+void tst_QWidget::openModal_taskQTBUG_5804()
+{
+    class Widget : public QWidget
+    {
+    public:
+        Widget(QWidget *parent) : QWidget(parent)
+        {
+        }
+        ~Widget()
+        {
+            QMessageBox msgbox;
+            QTimer::singleShot(10, &msgbox, SLOT(accept()));
+            msgbox.exec(); //open a modal dialog
+        }
+    };
+
+    QWidget *win = new QWidget;
+    new Widget(win);
+    win->show();
+    QTest::qWaitForWindowShown(win);
+    delete win;
+}
+
 #ifdef Q_OS_SYMBIAN
 void tst_QWidget::cbaVisibility()
 {