Have XCB/Windows platform integration classes keep their own instance pointer

Through the chain of code called by QPlatformIntegrationFactory::create, there
are cases where QGuiApplicationPrivate::platform_integration is accessed
(typically through QGuiApplicationPrivate::platformIntegration()) before the call
to QPlatformIntegrationFactory::create has returned.

Change-Id: I7805b72be5b56aed5cb8ce30cb908743c9b1f91b
Task-number: QTBUG-44388
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>

src/plugins/platforms/windows/qwindowsintegration.cpp

@@ -235,9 +235,12 @@ QWindowsIntegrationPrivate::~QWindowsIntegrationPrivate()
         delete m_fontDatabase;
 }
 
+QWindowsIntegration *QWindowsIntegration::m_instance = Q_NULLPTR;
+
 QWindowsIntegration::QWindowsIntegration(const QStringList &paramList) :
     d(new QWindowsIntegrationPrivate(paramList))
 {
+    m_instance = this;
 #ifndef QT_NO_CLIPBOARD
     d->m_clipboard.registerViewer();
 #endif
@@ -246,6 +249,7 @@ QWindowsIntegration::QWindowsIntegration(const QStringList &paramList) :
 
 QWindowsIntegration::~QWindowsIntegration()
 {
+    m_instance = Q_NULLPTR;
 }
 
 void QWindowsIntegration::initialize()
@@ -540,11 +544,6 @@ QPlatformAccessibility *QWindowsIntegration::accessibility() const
 }
 #endif
 
-QWindowsIntegration *QWindowsIntegration::instance()
-{
-    return static_cast<QWindowsIntegration *>(QGuiApplicationPrivate::platformIntegration());
-}
-
 unsigned QWindowsIntegration::options() const
 {
     return d->m_options;

src/plugins/platforms/windows/qwindowsintegration.h

@@ -91,7 +91,7 @@ public:
     Qt::KeyboardModifiers queryKeyboardModifiers() const Q_DECL_OVERRIDE;
     QList<int> possibleKeys(const QKeyEvent *e) const Q_DECL_OVERRIDE;
 
-    static QWindowsIntegration *instance();
+    static QWindowsIntegration *instance() { return m_instance; }
 
     inline void emitScreenAdded(QPlatformScreen *s) { screenAdded(s); }
     inline void emitDestroyScreen(QPlatformScreen *s) { destroyScreen(s); }
@@ -104,6 +104,8 @@ public:
 
 private:
     QScopedPointer<QWindowsIntegrationPrivate> d;
+
+    static QWindowsIntegration *m_instance;
 };
 
 QT_END_NAMESPACE

src/plugins/platforms/xcb/gl_integrations/xcb_egl/qxcbeglnativeinterfacehandler.cpp

@@ -100,7 +100,7 @@ QPlatformNativeInterface::NativeResourceForWindowFunction QXcbEglNativeInterface
 
 void *QXcbEglNativeInterfaceHandler::eglDisplay()
 {
-    QXcbIntegration *integration = static_cast<QXcbIntegration *>(QGuiApplicationPrivate::platformIntegration());
+    QXcbIntegration *integration = QXcbIntegration::instance();
     QXcbEglIntegration *eglIntegration = static_cast<QXcbEglIntegration *>(integration->defaultConnection()->glIntegration());
     return eglIntegration->eglDisplay();
 }

src/plugins/platforms/xcb/qxcbconnection.cpp

@@ -240,7 +240,7 @@ void QXcbConnection::updateScreens()
         ++xcbScreenNumber;
     } // for each xcb screen
 
-    QXcbIntegration *integration = static_cast<QXcbIntegration *>(QGuiApplicationPrivate::platformIntegration());
+    QXcbIntegration *integration = QXcbIntegration::instance();
     // Now activeScreens is the complete set of screens which are active at this time.
     // Delete any existing screens which are not in activeScreens
     for (int i = m_screens.count() - 1; i >= 0; --i) {
@@ -404,7 +404,7 @@ QXcbConnection::~QXcbConnection()
 
     delete m_reader;
 
-    QXcbIntegration *integration = static_cast<QXcbIntegration *>(QGuiApplicationPrivate::platformIntegration());
+    QXcbIntegration *integration = QXcbIntegration::instance();
     // Delete screens in reverse order to avoid crash in case of multiple screens
     while (!m_screens.isEmpty())
         integration->destroyScreen(m_screens.takeLast());

src/plugins/platforms/xcb/qxcbintegration.cpp

@@ -110,11 +110,15 @@ static bool runningUnderDebugger()
 #endif
 }
 
+QXcbIntegration *QXcbIntegration::m_instance = Q_NULLPTR;
+
 QXcbIntegration::QXcbIntegration(const QStringList &parameters, int &argc, char **argv)
     : m_services(new QGenericUnixServices)
     , m_instanceName(0)
     , m_canGrab(true)
 {
+    m_instance = this;
+
     qRegisterMetaType<QXcbWindow*>();
 #ifdef XCB_USE_XLIB
     XInitThreads();
@@ -179,6 +183,7 @@ QXcbIntegration::QXcbIntegration(const QStringList &parameters, int &argc, char
 QXcbIntegration::~QXcbIntegration()
 {
     qDeleteAll(m_connections);
+    m_instance = Q_NULLPTR;
 }
 
 QPlatformWindow *QXcbIntegration::createPlatformWindow(QWindow *window) const

src/plugins/platforms/xcb/qxcbintegration.h

@@ -101,6 +101,9 @@ public:
 #endif
 
     void sync() Q_DECL_OVERRIDE;
+
+    static QXcbIntegration *instance() { return m_instance; }
+
 private:
     QList<QXcbConnection *> m_connections;
 
@@ -120,6 +123,8 @@ private:
     mutable QByteArray m_wmClass;
     const char *m_instanceName;
     bool m_canGrab;
+
+    static QXcbIntegration *m_instance;
 };
 
 QT_END_NAMESPACE

src/plugins/platforms/xcb/qxcbnativeinterface.cpp

@@ -401,7 +401,7 @@ void *QXcbNativeInterface::getTimestamp(const QXcbScreen *screen)
 
 void *QXcbNativeInterface::startupId()
 {
-    QXcbIntegration* integration = static_cast<QXcbIntegration *>(QGuiApplicationPrivate::platformIntegration());
+    QXcbIntegration* integration = QXcbIntegration::instance();
     QXcbConnection *defaultConnection = integration->defaultConnection();
     if (defaultConnection)
         return reinterpret_cast<void *>(const_cast<char *>(defaultConnection->startupId().constData()));
@@ -410,7 +410,7 @@ void *QXcbNativeInterface::startupId()
 
 void *QXcbNativeInterface::x11Screen()
 {
-    QXcbIntegration *integration = static_cast<QXcbIntegration *>(QGuiApplicationPrivate::platformIntegration());
+    QXcbIntegration *integration = QXcbIntegration::instance();
     QXcbConnection *defaultConnection = integration->defaultConnection();
     if (defaultConnection)
         return reinterpret_cast<void *>(defaultConnection->primaryScreenNumber());
@@ -419,7 +419,7 @@ void *QXcbNativeInterface::x11Screen()
 
 void *QXcbNativeInterface::rootWindow()
 {
-    QXcbIntegration *integration = static_cast<QXcbIntegration *>(QGuiApplicationPrivate::platformIntegration());
+    QXcbIntegration *integration = QXcbIntegration::instance();
     QXcbConnection *defaultConnection = integration->defaultConnection();
     if (defaultConnection)
         return reinterpret_cast<void *>(defaultConnection->rootWindow());
@@ -429,7 +429,7 @@ void *QXcbNativeInterface::rootWindow()
 void *QXcbNativeInterface::display()
 {
 #ifdef XCB_USE_XLIB
-    QXcbIntegration *integration = static_cast<QXcbIntegration *>(QGuiApplicationPrivate::platformIntegration());
+    QXcbIntegration *integration = QXcbIntegration::instance();
     QXcbConnection *defaultConnection = integration->defaultConnection();
     return defaultConnection->xlib_display();
 #else
@@ -450,7 +450,7 @@ void QXcbNativeInterface::setAppUserTime(QScreen* screen, xcb_timestamp_t time)
 void QXcbNativeInterface::setStartupId(const char *data)
 {
     QByteArray startupId(data);
-    QXcbIntegration *integration = static_cast<QXcbIntegration *>(QGuiApplicationPrivate::platformIntegration());
+    QXcbIntegration *integration = QXcbIntegration::instance();
     QXcbConnection *defaultConnection = integration->defaultConnection();
     if (defaultConnection)
         defaultConnection->setStartupId(startupId);

src/plugins/platforms/xcb/qxcbwindow.cpp

@@ -461,7 +461,7 @@ void QXcbWindow::create()
     m_syncValue.hi = 0;
     m_syncValue.lo = 0;
 
-    const QByteArray wmClass = static_cast<QXcbIntegration *>(QGuiApplicationPrivate::platformIntegration())->wmClass();
+    const QByteArray wmClass = QXcbIntegration::instance()->wmClass();
     if (!wmClass.isEmpty()) {
         Q_XCB_CALL(xcb_change_property(xcb_connection(), XCB_PROP_MODE_REPLACE,
                                        m_window, atom(QXcbAtom::WM_CLASS),