Accessibility: Fix crash when updating in dtor

This happens for example when running several tests.
Widgets in destructor should be treated as invalid
since their window pointer and other properties are
no longer valid.

When deleting a window containing only a table view
there would be a table model reset update comming from
the window being destroyed.

Change-Id: Ia387c814333ce373fe132b189fc180787e36cdd5
Reviewed-by: Jan Arve Sæther <jan-arve.saether@digia.com>

src/platformsupport/linuxaccessibility/atspiadaptor.cpp

@@ -809,9 +809,13 @@ void AtSpiAdaptor::windowActivated(QObject* window, bool active)
         return;
 
     QAccessibleInterface *iface = QAccessible::queryAccessibleInterface(window);
-    Q_ASSERT(iface && iface->isValid());
+    Q_ASSERT(iface);
+    Q_ASSERT(!active || iface->isValid());
 
-    QString windowTitle = iface->text(QAccessible::Name);
+    QString windowTitle;
+    // in dtor it may be invalid
+    if (iface->isValid())
+        windowTitle = iface->text(QAccessible::Name);
     delete iface;
 
     QDBusVariant data;

src/plugins/accessible/widgets/itemviews.cpp

@@ -47,7 +47,7 @@
 #include <qtreeview.h>
 #include <private/qtreewidget_p.h>
 #include <QtGui/private/qaccessible2_p.h>
-#include <QDebug>
+#include <QtWidgets/private/qwidget_p.h>
 
 #ifndef QT_NO_ACCESSIBILITY
 
@@ -136,6 +136,11 @@ QAccessibleTable::QAccessibleTable(QWidget *w)
     }
 }
 
+bool QAccessibleTable::isValid() const
+{
+    return (view() && !qobject_cast<QWidget*>(view())->d_func()->data.in_destructor);
+}
+
 QAccessibleTable::~QAccessibleTable()
 {
 }

src/plugins/accessible/widgets/itemviews.h

@@ -63,6 +63,7 @@ class QAccessibleTable :public QAccessibleTableInterface, public QAccessibleObje
 {
 public:
     explicit QAccessibleTable(QWidget *w);
+    bool isValid() const;
 
     virtual ~QAccessibleTable();
 

src/widgets/accessible/qaccessiblewidget.cpp

@@ -55,6 +55,7 @@
 #include <QRubberBand>
 #include <QFocusFrame>
 #include <QMenu>
+#include <QtWidgets/private/qwidget_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -152,6 +153,7 @@ QString Q_WIDGETS_EXPORT qt_accHotKey(const QString &text)
     return QString();
 }
 
+// ### inherit QAccessibleObjectPrivate
 class QAccessibleWidgetPrivate
 {
 public:
@@ -202,6 +204,13 @@ QAccessibleWidget::QAccessibleWidget(QWidget *w, QAccessible::Role role, const Q
     d->name = name;
 }
 
+bool QAccessibleWidget::isValid() const
+{
+    if (!object() || static_cast<QWidget *>(object())->d_func()->data.in_destructor)
+        return false;
+    return QAccessibleObject::isValid();
+}
+
 /*! \reimp */
 QWindow *QAccessibleWidget::window() const
 {

src/widgets/accessible/qaccessiblewidget_p.h

@@ -56,6 +56,7 @@ class Q_WIDGETS_EXPORT QAccessibleWidget : public QAccessibleObject, public QAcc
 {
 public:
     explicit QAccessibleWidget(QWidget *o, QAccessible::Role r = QAccessible::Client, const QString& name = QString());
+    bool isValid() const;
 
     QWindow *window() const;
     int childCount() const;

src/widgets/kernel/qwidget.h

@@ -704,6 +704,8 @@ private:
     friend class QStyleSheetStyle;
     friend struct QWidgetExceptionCleaner;
     friend class QWidgetWindow;
+    friend class QAccessibleWidget;
+    friend class QAccessibleTable;
 #ifndef QT_NO_GESTURES
     friend class QGestureManager;
     friend class QWinNativePanGestureRecognizer;