Fix crash on Qt.quit in applications

The backing QQuickWindow might die earlier than our
ApplicationManagerWindow, so we need to be prepared for that.
This only ever crashed in the destructor, but this patch adds checks
to every m_qwindow access: better be safe than sorry.

Change-Id: I764a796ff8c5c09fb21175d8add51933ffe82ded
Pick-to: 6.7
Reviewed-by: Dominik Holland <dominik.holland@qt.io>

2 files changed, 65 insertions, 39 deletions

diff --git a/src/application-main-lib/waylandapplicationmanagerwindowimpl.cpp b/src/application-main-lib/waylandapplicationmanagerwindowimpl.cpp
index e30217f5..f4a53f1b 100644
--- a/src/application-main-lib/waylandapplicationmanagerwindowimpl.cpp
+++ b/src/application-main-lib/waylandapplicationmanagerwindowimpl.cpp
@@ -80,13 +80,19 @@ WaylandApplicationManagerWindowImpl::WaylandApplicationManagerWindowImpl(Applica
                      window, &ApplicationManagerWindow::afterAnimating);
     QObject::connect(m_qwindow, &AMQuickWindowQmlImpl::sceneGraphError,
                      window, &ApplicationManagerWindow::sceneGraphError);
+
+    QObject::connect(m_qwindow, &QObject::destroyed,
+                     window, [this, deadWindow = m_qwindow.get()](QObject *) {
+        if (m_applicationMain)
+            m_applicationMain->clearWindowPropertyCache(deadWindow);
+    });
 }
 
 WaylandApplicationManagerWindowImpl::~WaylandApplicationManagerWindowImpl()
 {
     if (m_applicationMain && m_qwindow)
-        m_applicationMain->clearWindowPropertyCache(m_qwindow);
-    delete m_qwindow;
+        m_applicationMain->clearWindowPropertyCache(m_qwindow.get());
+    delete m_qwindow.get();
 }
 
 bool WaylandApplicationManagerWindowImpl::isInProcess() const
@@ -96,7 +102,7 @@ bool WaylandApplicationManagerWindowImpl::isInProcess() const
 
 QObject *WaylandApplicationManagerWindowImpl::backingObject() const
 {
-    return m_qwindow;
+    return m_qwindow.get();
 }
 
 void WaylandApplicationManagerWindowImpl::classBegin()
@@ -167,177 +173,197 @@ QVariantMap WaylandApplicationManagerWindowImpl::windowProperties() const
 
 void WaylandApplicationManagerWindowImpl::close()
 {
-    m_qwindow->close();
+    if (m_qwindow)
+        m_qwindow->close();
 }
 
 QWindow::Visibility WaylandApplicationManagerWindowImpl::visibility() const
 {
-    return m_qwindow->visibility();
+    return m_qwindow ? m_qwindow->visibility() : QWindow::Hidden;
 }
 
 void WaylandApplicationManagerWindowImpl::setVisibility(QWindow::Visibility newVisibility)
 {
-    m_qwindow->setVisibility(newVisibility);
+    if (m_qwindow)
+        m_qwindow->setVisibility(newVisibility);
 }
 
 void WaylandApplicationManagerWindowImpl::hide()
 {
-    m_qwindow->hide();
+    if (m_qwindow)
+        m_qwindow->hide();
 }
 
 void WaylandApplicationManagerWindowImpl::show()
 {
-    m_qwindow->show();
+    if (m_qwindow)
+        m_qwindow->show();
 }
 
 void WaylandApplicationManagerWindowImpl::showFullScreen()
 {
-    m_qwindow->showFullScreen();
+    if (m_qwindow)
+        m_qwindow->showFullScreen();
 }
 
 void WaylandApplicationManagerWindowImpl::showMinimized()
 {
-    m_qwindow->showMinimized();
+    if (m_qwindow)
+        m_qwindow->showMinimized();
 }
 
 void WaylandApplicationManagerWindowImpl::showMaximized()
 {
-    m_qwindow->showMaximized();
+    if (m_qwindow)
+        m_qwindow->showMaximized();
 }
 
 void WaylandApplicationManagerWindowImpl::showNormal()
 {
-    m_qwindow->showNormal();
+    if (m_qwindow)
+        m_qwindow->showNormal();
 }
 
 QString WaylandApplicationManagerWindowImpl::title() const
 {
-    return m_qwindow->title();
+    return m_qwindow ? m_qwindow->title() : QString { };
 }
 
 void WaylandApplicationManagerWindowImpl::setTitle(const QString &title)
 {
-    m_qwindow->setTitle(title);
+    if (m_qwindow)
+        m_qwindow->setTitle(title);
 }
 
 int WaylandApplicationManagerWindowImpl::x() const
 {
-    return m_qwindow->x();
+    return m_qwindow ? m_qwindow->x() : 0;
 }
 
 void WaylandApplicationManagerWindowImpl::setX(int x)
 {
-    m_qwindow->setX(x);
+    if (m_qwindow)
+        m_qwindow->setX(x);
 }
 
 int WaylandApplicationManagerWindowImpl::y() const
 {
-    return m_qwindow->y();
+    return m_qwindow ? m_qwindow->y() : 0;
 }
 
 void WaylandApplicationManagerWindowImpl::setY(int y)
 {
-    m_qwindow->setY(y);
+    if (m_qwindow)
+        m_qwindow->setY(y);
 }
 
 int WaylandApplicationManagerWindowImpl::width() const
 {
-    return m_qwindow->width();
+    return m_qwindow ? m_qwindow->width() : 0;
 }
 
 void WaylandApplicationManagerWindowImpl::setWidth(int w)
 {
-    m_qwindow->setWidth(w);
+    if (m_qwindow)
+        m_qwindow->setWidth(w);
 }
 
 int WaylandApplicationManagerWindowImpl::height() const
 {
-    return m_qwindow->height();
+    return m_qwindow ? m_qwindow->height() : 0;
 }
 
 void WaylandApplicationManagerWindowImpl::setHeight(int h)
 {
-    m_qwindow->setHeight(h);
+    if (m_qwindow)
+        m_qwindow->setHeight(h);
 }
 
 int WaylandApplicationManagerWindowImpl::minimumWidth() const
 {
-    return m_qwindow->minimumWidth();
+    return m_qwindow ? m_qwindow->minimumWidth() : 0;
 }
 
 void WaylandApplicationManagerWindowImpl::setMinimumWidth(int minw)
 {
-    m_qwindow->setMinimumWidth(minw);
+    if (m_qwindow)
+        m_qwindow->setMinimumWidth(minw);
 }
 
 int WaylandApplicationManagerWindowImpl::minimumHeight() const
 {
-    return m_qwindow->minimumHeight();
+    return m_qwindow ? m_qwindow->minimumHeight() : 0;
 }
 
 void WaylandApplicationManagerWindowImpl::setMinimumHeight(int minh)
 {
-    m_qwindow->setMinimumHeight(minh);
+    if (m_qwindow)
+        m_qwindow->setMinimumHeight(minh);
 }
 
 int WaylandApplicationManagerWindowImpl::maximumWidth() const
 {
-    return m_qwindow->maximumWidth();
+    return m_qwindow ? m_qwindow->maximumWidth() : 0;
 }
 
 void WaylandApplicationManagerWindowImpl::setMaximumWidth(int maxw)
 {
-    m_qwindow->setMaximumWidth(maxw);
+    if (m_qwindow)
+        m_qwindow->setMaximumWidth(maxw);
 }
 
 int WaylandApplicationManagerWindowImpl::maximumHeight() const
 {
-    return m_qwindow->maximumHeight();
+    return m_qwindow ? m_qwindow->maximumHeight() : 0;
 }
 
 void WaylandApplicationManagerWindowImpl::setMaximumHeight(int maxh)
 {
-    m_qwindow->setMaximumHeight(maxh);
+    if (m_qwindow)
+        m_qwindow->setMaximumHeight(maxh);
 }
 
 bool WaylandApplicationManagerWindowImpl::isVisible() const
 {
-    return m_qwindow->isVisible();
+    return m_qwindow ? m_qwindow->isVisible() : false;
 }
 
 void WaylandApplicationManagerWindowImpl::setVisible(bool visible)
 {
-    m_qwindow->setVisible(visible);
+    if (m_qwindow)
+        m_qwindow->setVisible(visible);
 }
 
 qreal WaylandApplicationManagerWindowImpl::opacity() const
 {
-    return m_qwindow->opacity();
+    return m_qwindow ? m_qwindow->opacity() : qreal(1);
 }
 
 void WaylandApplicationManagerWindowImpl::setOpacity(qreal opactity)
 {
-    m_qwindow->setOpacity(opactity);
+    if (m_qwindow)
+        m_qwindow->setOpacity(opactity);
 }
 
 QColor WaylandApplicationManagerWindowImpl::color() const
 {
-    return m_qwindow->color();
+    return m_qwindow ? m_qwindow->color() : QColor { };
 }
 
 void WaylandApplicationManagerWindowImpl::setColor(const QColor &c)
 {
-    m_qwindow->setColor(c);
+    if (m_qwindow)
+        m_qwindow->setColor(c);
 }
 
 bool WaylandApplicationManagerWindowImpl::isActive() const
 {
-    return m_qwindow->isActive();
+    return m_qwindow ? m_qwindow->isActive(): false;
 }
 
 QQuickItem *WaylandApplicationManagerWindowImpl::activeFocusItem() const
 {
-    return m_qwindow->activeFocusItem();
+    return m_qwindow ? m_qwindow->activeFocusItem() : nullptr;
 }
 
 
diff --git a/src/application-main-lib/waylandapplicationmanagerwindowimpl.h b/src/application-main-lib/waylandapplicationmanagerwindowimpl.h
index 93331a55..1ade17a3 100644
--- a/src/application-main-lib/waylandapplicationmanagerwindowimpl.h
+++ b/src/application-main-lib/waylandapplicationmanagerwindowimpl.h
@@ -73,7 +73,7 @@ public:
 
 private:
     QPointer<ApplicationMain> m_applicationMain;
-    AMQuickWindowQmlImpl *m_qwindow = nullptr;
+    QPointer<AMQuickWindowQmlImpl> m_qwindow;
 };