Fixed an on-exit crash for apps using GL.

If a QGLWidget is left on the heap when the QApplication destructor is
called, it will leave the QGLWidget in a broken state.
The widget itself is released and set to a non-created state,
which the associated QGLContext doesn't get notified about.
With this patch the QGLWidget knows when QWidget::destroy() is called
and can act acordingly.

Task-number: QT-3498, QTBUG-10995
Reviewed-by: Paul

6 files changed, 14 insertions, 5 deletions

diff --git a/src/gui/kernel/qwidget_mac.mm b/src/gui/kernel/qwidget_mac.mm
index 1928599..280712a 100644
--- a/src/gui/kernel/qwidget_mac.mm
+++ b/src/gui/kernel/qwidget_mac.mm
@@ -2688,6 +2688,7 @@ QWidget::macCGHandle() const
 void QWidget::destroy(bool destroyWindow, bool destroySubWindows)
 {
     Q_D(QWidget);
+    d->aboutToDestroy();
     if (!isWindow() && parentWidget())
         parentWidget()->d_func()->invalidateBuffer(d->effectiveRectFor(geometry()));
     d->deactivateWidgetCleanup();
@@ -3994,10 +3995,10 @@ static void qt_mac_update_widget_position(QWidget *q, QRect oldRect, QRect newRe
         (oldRect.isValid() == false || newRect.isValid() == false)  ||
 
         // the position update is a part of a drag-and-drop operation
-        QDragManager::self()->object || 
-        
-        // we are on Panther (no HIViewSetNeedsDisplayInRect) 
-        QSysInfo::MacintoshVersion < QSysInfo::MV_10_4 
+        QDragManager::self()->object ||
+
+        // we are on Panther (no HIViewSetNeedsDisplayInRect)
+        QSysInfo::MacintoshVersion < QSysInfo::MV_10_4
     ){
         HIViewSetFrame(view, &bounds);
         return;
diff --git a/src/gui/kernel/qwidget_p.h b/src/gui/kernel/qwidget_p.h
index 4247c3a..587d7fb 100644
--- a/src/gui/kernel/qwidget_p.h
+++ b/src/gui/kernel/qwidget_p.h
@@ -551,6 +551,11 @@ public:
     void setLayoutItemMargins(int left, int top, int right, int bottom);
     void setLayoutItemMargins(QStyle::SubElement element, const QStyleOption *opt = 0);
 
+    // aboutToDestroy() is called just before the contents of
+    // QWidget::destroy() is executed. It's used to signal QWidget
+    // sub-classes that their internals are about to be released.
+    virtual void aboutToDestroy() {}
+
     QInputContext *inputContext() const;
     inline QWidget *effectiveFocusWidget() {
         QWidget *w = q_func();
diff --git a/src/gui/kernel/qwidget_qws.cpp b/src/gui/kernel/qwidget_qws.cpp
index b827e8b..3145136 100644
--- a/src/gui/kernel/qwidget_qws.cpp
+++ b/src/gui/kernel/qwidget_qws.cpp
@@ -256,7 +256,7 @@ void QWidgetPrivate::create_sys(WId window, bool initializeWindow, bool /*destro
 void QWidget::destroy(bool destroyWindow, bool destroySubWindows)
 {
     Q_D(QWidget);
-
+    d->aboutToDestroy();
     if (!isWindow() && parentWidget())
         parentWidget()->d_func()->invalidateBuffer(d->effectiveRectFor(geometry()));
 
diff --git a/src/gui/kernel/qwidget_s60.cpp b/src/gui/kernel/qwidget_s60.cpp
index 86b858d..68f9470 100644
--- a/src/gui/kernel/qwidget_s60.cpp
+++ b/src/gui/kernel/qwidget_s60.cpp
@@ -1177,6 +1177,7 @@ void QWidget::setWindowState(Qt::WindowStates newstate)
 void QWidget::destroy(bool destroyWindow, bool destroySubWindows)
 {
     Q_D(QWidget);
+    d->aboutToDestroy();
     if (!isWindow() && parentWidget())
         parentWidget()->d_func()->invalidateBuffer(geometry());
     d->deactivateWidgetCleanup();
diff --git a/src/gui/kernel/qwidget_win.cpp b/src/gui/kernel/qwidget_win.cpp
index a7e66bf..9c65aa0 100644
--- a/src/gui/kernel/qwidget_win.cpp
+++ b/src/gui/kernel/qwidget_win.cpp
@@ -544,6 +544,7 @@ void QWidgetPrivate::create_sys(WId window, bool initializeWindow, bool destroyO
 void QWidget::destroy(bool destroyWindow, bool destroySubWindows)
 {
     Q_D(QWidget);
+    d->aboutToDestroy();
     if (!isWindow() && parentWidget())
         parentWidget()->d_func()->invalidateBuffer(d->effectiveRectFor(geometry()));
     d->deactivateWidgetCleanup();
diff --git a/src/gui/kernel/qwidget_x11.cpp b/src/gui/kernel/qwidget_x11.cpp
index 43f510c..e01489f 100644
--- a/src/gui/kernel/qwidget_x11.cpp
+++ b/src/gui/kernel/qwidget_x11.cpp
@@ -1023,6 +1023,7 @@ bool QWidgetPrivate::isBackgroundInherited() const
 void QWidget::destroy(bool destroyWindow, bool destroySubWindows)
 {
     Q_D(QWidget);
+    d->aboutToDestroy();
     if (!isWindow() && parentWidget())
         parentWidget()->d_func()->invalidateBuffer(d->effectiveRectFor(geometry()));
     d->deactivateWidgetCleanup();