Emit destroyed() signal before children get deleted

Make sure we always emit the destroyed() signal before
we delete our children. This wasn't working correctly
for QWidget based classes, as the QWidget destructor
deletes all children itself.

Task-number: QTBUG-24672
Change-Id: Iecdff3489196271177edfeba1c4a2c5800e255af
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>

1 files changed, 100 insertions, 0 deletions

diff --git a/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp b/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
index f3f63b2067..2a5e59f825 100644
--- a/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
+++ b/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
@@ -396,6 +396,8 @@ private slots:
     void touchEventSynthesizedMouseEvent();
 
     void styleSheetPropagation();
+
+    void destroyedSignal();
 private:
     bool ensureScreenSize(int width, int height);
     QWidget *testWidget;
@@ -9592,6 +9594,104 @@ void tst_QWidget::styleSheetPropagation()
     }
 }
 
+class DestroyTester : public QObject
+{
+    Q_OBJECT
+public:
+    DestroyTester(QObject *parent) : QObject(parent) { parentDestroyed = 0; }
+    static int parentDestroyed;
+public slots:
+    void parentDestroyedSlot() {
+        ++parentDestroyed;
+    }
+};
+
+int DestroyTester::parentDestroyed = 0;
+
+void tst_QWidget::destroyedSignal()
+{
+    {
+        QWidget *w = new QWidget;
+        DestroyTester *t = new DestroyTester(w);
+        connect(w, SIGNAL(destroyed()), t, SLOT(parentDestroyedSlot()));
+        QCOMPARE(DestroyTester::parentDestroyed, 0);
+        delete w;
+        QCOMPARE(DestroyTester::parentDestroyed, 1);
+    }
+
+    {
+        QWidget *w = new QWidget;
+        DestroyTester *t = new DestroyTester(w);
+        connect(w, SIGNAL(destroyed()), t, SLOT(parentDestroyedSlot()));
+        w->blockSignals(true);
+        QCOMPARE(DestroyTester::parentDestroyed, 0);
+        delete w;
+        QCOMPARE(DestroyTester::parentDestroyed, 1);
+    }
+
+    {
+        QObject *o = new QWidget;
+        DestroyTester *t = new DestroyTester(o);
+        connect(o, SIGNAL(destroyed()), t, SLOT(parentDestroyedSlot()));
+        QCOMPARE(DestroyTester::parentDestroyed, 0);
+        delete o;
+        QCOMPARE(DestroyTester::parentDestroyed, 1);
+    }
+
+    {
+        QObject *o = new QWidget;
+        DestroyTester *t = new DestroyTester(o);
+        connect(o, SIGNAL(destroyed()), t, SLOT(parentDestroyedSlot()));
+        o->blockSignals(true);
+        QCOMPARE(DestroyTester::parentDestroyed, 0);
+        delete o;
+        QCOMPARE(DestroyTester::parentDestroyed, 1);
+    }
+
+    {
+        QWidget *w = new QWidget;
+        DestroyTester *t = new DestroyTester(0);
+        connect(w, SIGNAL(destroyed()), t, SLOT(parentDestroyedSlot()));
+        QCOMPARE(DestroyTester::parentDestroyed, 0);
+        delete w;
+        QCOMPARE(DestroyTester::parentDestroyed, 1);
+        delete t;
+    }
+
+    {
+        QWidget *w = new QWidget;
+        DestroyTester *t = new DestroyTester(0);
+        connect(w, SIGNAL(destroyed()), t, SLOT(parentDestroyedSlot()));
+        w->blockSignals(true);
+        QCOMPARE(DestroyTester::parentDestroyed, 0);
+        delete w;
+        QCOMPARE(DestroyTester::parentDestroyed, 1);
+        delete t;
+    }
+
+    {
+        QObject *o = new QWidget;
+        DestroyTester *t = new DestroyTester(0);
+        connect(o, SIGNAL(destroyed()), t, SLOT(parentDestroyedSlot()));
+        QCOMPARE(DestroyTester::parentDestroyed, 0);
+        delete o;
+        QCOMPARE(DestroyTester::parentDestroyed, 1);
+        delete t;
+    }
+
+    {
+        QObject *o = new QWidget;
+        DestroyTester *t = new DestroyTester(0);
+        connect(o, SIGNAL(destroyed()), t, SLOT(parentDestroyedSlot()));
+        o->blockSignals(true);
+        QCOMPARE(DestroyTester::parentDestroyed, 0);
+        delete o;
+        QCOMPARE(DestroyTester::parentDestroyed, 1);
+        delete t;
+    }
+
+}
+
 #ifndef QTEST_NO_CURSOR
 void tst_QWidget::underMouse()
 {