QQuickWindow: disconnect incoming signals in dtor to avoid assert

qtbase commit 92a65fdac69d7773b114584f1637946622cf4f72 changed what
happened when deleting a QWindow with child windows: they are now
deleted earlier, from ~QWindow rather than from ~QObject.

As a consequence, if the deletion of the child window triggers any
signal (such as QSGRenderContext::invalidated), the parent window
now receives it (while before, the code in ~QObject would disconnect
the parent window from all senders).

Fixed by explicit disconnects, using a std::array of
QMetaObject::Connections, like in QSortFilterProxyModel for instance.

Task-number: QTBUG-140170
Change-Id: Id2c402d3121c8a3e6962cfed0afe1e90f5f14b3f
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
(cherry picked from commit a346f6d0f3a26b134060b8d3f9e008a8e08353b9)
Reviewed-by: Akseli Salovaara <akseli.salovaara@qt.io>

2 files changed, 13 insertions, 7 deletions

diff --git a/src/quick/items/qquickwindow.cpp b/src/quick/items/qquickwindow.cpp
index 60c4c1633e..f1b131e7e9 100644
--- a/src/quick/items/qquickwindow.cpp
+++ b/src/quick/items/qquickwindow.cpp
@@ -817,14 +817,16 @@ void QQuickWindowPrivate::init(QQuickWindow *c, QQuickRenderControl *control)
 
     animationController.reset(new QQuickAnimatorController(q));
 
-    QObject::connect(context, &QSGRenderContext::initialized, q, &QQuickWindow::sceneGraphInitialized, Qt::DirectConnection);
-    QObject::connect(context, &QSGRenderContext::invalidated, q, &QQuickWindow::sceneGraphInvalidated, Qt::DirectConnection);
-    QObject::connect(context, &QSGRenderContext::invalidated, q, &QQuickWindow::cleanupSceneGraph, Qt::DirectConnection);
+    connections = {
+        QObject::connect(context, &QSGRenderContext::initialized, q, &QQuickWindow::sceneGraphInitialized, Qt::DirectConnection),
+        QObject::connect(context, &QSGRenderContext::invalidated, q, &QQuickWindow::sceneGraphInvalidated, Qt::DirectConnection),
+        QObject::connect(context, &QSGRenderContext::invalidated, q, &QQuickWindow::cleanupSceneGraph, Qt::DirectConnection),
 
-    QObject::connect(q, &QQuickWindow::focusObjectChanged, q, &QQuickWindow::activeFocusItemChanged);
-    QObject::connect(q, &QQuickWindow::screenChanged, q, &QQuickWindow::handleScreenChanged);
-    QObject::connect(qApp, &QGuiApplication::applicationStateChanged, q, &QQuickWindow::handleApplicationStateChanged);
-    QObject::connect(q, &QQuickWindow::frameSwapped, q, &QQuickWindow::runJobsAfterSwap, Qt::DirectConnection);
+        QObject::connect(q, &QQuickWindow::focusObjectChanged, q, &QQuickWindow::activeFocusItemChanged),
+        QObject::connect(q, &QQuickWindow::screenChanged, q, &QQuickWindow::handleScreenChanged),
+        QObject::connect(qApp, &QGuiApplication::applicationStateChanged, q, &QQuickWindow::handleApplicationStateChanged),
+        QObject::connect(q, &QQuickWindow::frameSwapped, q, &QQuickWindow::runJobsAfterSwap, Qt::DirectConnection),
+    };
 
     if (QQmlInspectorService *service = QQmlDebugConnector::service<QQmlInspectorService>())
         service->addWindow(q);
@@ -1213,6 +1215,9 @@ QQuickWindow::~QQuickWindow()
     // have their destructors loaded while they the library is still
     // loaded into memory.
     QQuickPixmap::purgeCache();
+
+    for (const QMetaObject::Connection &connection : d->connections)
+        disconnect(connection);
 }
 
 #if QT_CONFIG(quick_shadereffect)
diff --git a/src/quick/items/qquickwindow_p.h b/src/quick/items/qquickwindow_p.h
index f4769a8c7f..8da8b0b6c0 100644
--- a/src/quick/items/qquickwindow_p.h
+++ b/src/quick/items/qquickwindow_p.h
@@ -194,6 +194,7 @@ public:
 
     qreal lastReportedItemDevicePixelRatio;
     QMetaObject::Connection physicalDpiChangedConnection;
+    std::array<QMetaObject::Connection, 7> connections;
 
     void updateDirtyNodes();
     void cleanupNodes();