Qt: Improve cleanup flow, fix crashes when exiting with OpenGL renderer

Author: endrift

CHANGES

@@ -54,6 +54,7 @@ Other fixes:
  - Qt: Fix selecting high tiles in tile and map views (fixes mgba.io/i/3461)
  - Qt: Fix some actions disabled in multiplayer staying disabled after closing game
  - Qt: Fix unexpected mute when window becomes focused while fast-forwarding
+ - Qt: Fix crashes when exiting with OpenGL renderer
 Misc:
  - 3DS: Change title ID to avoid conflict with commercial title (fixes mgba.io/i/3023)
  - Core: Handle relative paths for saves, screenshots, etc consistently (fixes mgba.io/i/2826)

src/platform/qt/DisplayGL.cpp

@@ -917,9 +917,6 @@ void PainterGL::doStop() {
 	m_started = false;
 	dequeueAll(false);
 	if (m_context) {
-		if (m_videoProxy) {
-			m_videoProxy->detach(m_context.get());
-		}
 		m_context->setFramebufferHandle(-1);
 		m_context.reset();
 		if (m_videoProxy) {

src/platform/qt/Window.cpp

@@ -992,12 +992,7 @@ void Window::gameStopped() {
 #endif
 	}
 
-	std::shared_ptr<CoreController> controller;
-	m_controller.swap(controller);
-	QTimer::singleShot(0, this, [controller]() {
-		// Destroy the controller after everything else has cleaned up
-		Q_UNUSED(controller);
-	});
+	m_cleanupController = std::move(m_controller);
 	detachWidget();
 	updateTitle();
 
@@ -1008,9 +1003,10 @@ void Window::gameStopped() {
 			m_scripting->setVideoBackend(nullptr);
 		}
 #endif
-		m_display.reset();
+		m_cleanupDisplay = std::move(m_display);
 		close();
 	}
+	QTimer::singleShot(0, this, &Window::delayedCleanup);
 #ifndef Q_OS_MAC
 	showMenu(true);
 #endif
@@ -2360,6 +2356,13 @@ void Window::setLogo() {
 	centralWidget()->unsetCursor();
 }
 
+void Window::delayedCleanup() {
+	// Destroy the controller after everything else has cleaned up, except for the display
+	m_cleanupController.reset();
+	// The display needs to be cleaned up last so the core can clean up the OpenGL resources
+	m_cleanupDisplay.reset();
+}
+
 WindowBackground::WindowBackground(QWidget* parent)
 	: QWidget(parent)
 {

src/platform/qt/Window.h

@@ -161,6 +161,8 @@ private slots:
 
 	void setLogo();
 
+	void delayedCleanup();
+
 private:
 	static const int FPS_TIMER_INTERVAL = 2000;
 	static const int MUST_RESTART_TIMEOUT = 10000;
@@ -266,6 +268,9 @@ private slots:
 #ifdef ENABLE_SCRIPTING
 	std::unique_ptr<ScriptingController> m_scripting;
 #endif
+
+	std::unique_ptr<QGBA::Display> m_cleanupDisplay;
+	std::shared_ptr<CoreController> m_cleanupController;
 };
 
 class WindowBackground : public QWidget {