Fix crashes when moving descendents during destruction.

This fix prevents crashes in
QGraphicsItem caused by calls to pure virtual functions as an item
tries to access its dying parent. This happens when an item is moved
by an ancestor during this ancestor's destructor.

Autotests included.

Reviewed-by: bnilsen

1 files changed, 60 insertions, 0 deletions

diff --git a/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp b/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
index 408decc..77c2d45 100644
--- a/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
+++ b/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
@@ -292,6 +292,7 @@ private slots:
     void activate();
     void setActivePanelOnInactiveScene();
     void activationOnShowHide();
+    void moveWhileDeleting();
 
     // task specific tests below me
     void task141694_textItemEnsureVisible();
@@ -8103,5 +8104,64 @@ void tst_QGraphicsItem::activationOnShowHide()
     QVERIFY(otherItem->isActive());
 }
 
+class MoveWhileDying : public QGraphicsRectItem
+{
+public:
+    MoveWhileDying(QGraphicsItem *parent = 0)
+        : QGraphicsRectItem(parent)
+    { }
+    ~MoveWhileDying()
+    {
+        foreach (QGraphicsItem *c, childItems()) {
+            foreach (QGraphicsItem *cc, c->childItems()) {
+                cc->moveBy(10, 10);
+            }
+            c->moveBy(10, 10);
+        }
+        if (QGraphicsItem *p = parentItem()) { p->moveBy(10, 10); }
+    }
+};
+
+void tst_QGraphicsItem::moveWhileDeleting()
+{
+    QGraphicsScene scene;
+    QGraphicsRectItem *rect = new QGraphicsRectItem;
+    MoveWhileDying *silly = new MoveWhileDying(rect);
+    QGraphicsRectItem *child = new QGraphicsRectItem(silly);
+    scene.addItem(rect);
+    delete rect; // don't crash!
+
+    rect = new QGraphicsRectItem;
+    silly = new MoveWhileDying(rect);
+    child = new QGraphicsRectItem(silly);
+
+    QGraphicsView view(&scene);
+    view.show();
+#ifdef Q_WS_X11
+    qt_x11_wait_for_window_manager(&view);
+#endif
+    QTest::qWait(125);
+
+    delete rect;
+
+    rect = new QGraphicsRectItem;
+    rect->setFlag(QGraphicsItem::ItemClipsChildrenToShape);
+    silly = new MoveWhileDying(rect);
+    child = new QGraphicsRectItem(silly);
+
+    QTest::qWait(125);
+
+    delete rect;
+
+    rect = new MoveWhileDying;
+    rect->setFlag(QGraphicsItem::ItemClipsChildrenToShape);
+    child = new QGraphicsRectItem(rect);
+    silly = new MoveWhileDying(child);
+
+    QTest::qWait(125);
+
+    delete rect;
+}
+
 QTEST_MAIN(tst_QGraphicsItem)
 #include "tst_qgraphicsitem.moc"