Centralize maybeLastWindowClosed checking in QWindow

Instead of plumbing QWidgetWindow close events via handleCloseEvent,
we just implement closeEvent directly. This allows QWindow do save
the state of the window/widget before the close event, so that we
know whether we should trigger lastWindowClosed handling, even if
the window was deleted as a result of the close event.

This also relieves QGuiApplication and QApplication from dealing
with the close logic in their notify functions, so that these
functions can focus on the propagation of events -- not how the
event is handled.

Change-Id: I8b586b53a53b1df1d8630c1acb635c60f191bb4b
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

1 files changed, 12 insertions, 3 deletions

diff --git a/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp b/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
index aca40103df..27cf884fd5 100644
--- a/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
+++ b/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
@@ -12253,10 +12253,19 @@ protected:
 
 void tst_QWidget::deleteWindowInCloseEvent()
 {
-    // Just checking if closing this widget causes a crash
+    QSignalSpy quitSpy(qApp, &QGuiApplication::lastWindowClosed);
+
+    // Closing this widget should not cause a crash
     auto widget = new DeleteOnCloseEventWidget;
-    widget->close();
-    QVERIFY(true);
+    widget->show();
+    QVERIFY(QTest::qWaitForWindowExposed(widget));
+    QTimer::singleShot(0, widget, [&]{
+        widget->close();
+    });
+    QApplication::exec();
+
+    // It should still result in a single lastWindowClosed emit
+    QCOMPARE(quitSpy.count(), 1);
 }
 
 /*!