[wayland] Unload all effects prior to destroying Xwayland connection

Some effects do X11 calls in their cleanup code through external
libraries (e.g. KSelectionOwner). As we cannot control that we need
to ensure the effects are unloaded prior to destroying the Xwayland
connection.

autotests/wayland/kwin_wayland_test.cpp

@@ -19,6 +19,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *********************************************************************/
 #include "kwin_wayland_test.h"
 #include "../../abstract_backend.h"
+#include "../../effects.h"
 #include "../../wayland_server.h"
 #include "../../workspace.h"
 #include "../../xcbutils.h"
@@ -52,6 +53,10 @@ WaylandTestApplication::~WaylandTestApplication()
 {
     destroyWorkspace();
     waylandServer()->dispatch();
+    // need to unload all effects prior to destroying X connection as they might do X calls
+    if (effects) {
+        static_cast<EffectsHandlerImpl*>(effects)->unloadAllEffects();
+    }
     if (x11Connection()) {
         Xcb::setInputFocus(XCB_INPUT_FOCUS_POINTER_ROOT);
         destroyAtoms();

effects.cpp

@@ -315,6 +315,11 @@ EffectsHandlerImpl::EffectsHandlerImpl(Compositor *compositor, Scene *scene)
 }
 
 EffectsHandlerImpl::~EffectsHandlerImpl()
+{
+    unloadAllEffects();
+}
+
+void EffectsHandlerImpl::unloadAllEffects()
 {
     makeOpenGLContextCurrent();
     if (keyboard_grab_effect != NULL)

effects.h

@@ -62,7 +62,7 @@ class EffectLoader;
 class Unmanaged;
 class ScreenLockerWatcher;
 
-class EffectsHandlerImpl : public EffectsHandler
+class KWIN_EXPORT EffectsHandlerImpl : public EffectsHandler
 {
     Q_OBJECT
     Q_CLASSINFO("D-Bus Interface", "org.kde.kwin.Effects")
@@ -206,6 +206,7 @@ public:
     void reloadEffect(Effect *effect) override;
     QStringList loadedEffects() const;
     QStringList listOfEffects() const;
+    void unloadAllEffects();
 
     QList<EffectWindow*> elevatedWindows() const;
     QStringList activeEffects() const;

main_wayland.cpp

@@ -22,6 +22,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <config-kwin.h>
 // kwin
 #include "abstract_backend.h"
+#include "effects.h"
 #include "wayland_server.h"
 #include "xcbutils.h"
 
@@ -76,6 +77,10 @@ ApplicationWayland::~ApplicationWayland()
 {
     destroyWorkspace();
     waylandServer()->dispatch();
+    // need to unload all effects prior to destroying X connection as they might do X calls
+    if (effects) {
+        static_cast<EffectsHandlerImpl*>(effects)->unloadAllEffects();
+    }
     if (x11Connection()) {
         Xcb::setInputFocus(XCB_INPUT_FOCUS_POINTER_ROOT);
         destroyAtoms();