Fix postponed calls from crl::on_main() on macOS.

In libdispatch crl::on_main() implementation we bypass Application::notify() frame.
So we handle event loop nesting control manually by wrapping all invokations done
through crl::on_main() with the same methods we do from Application::notify().

Telegram/SourceFiles/application.cpp

@@ -416,12 +416,11 @@ void Application::postponeCall(FnMut<void()> &&callable) {
 	});
 }
 
-bool Application::notify(QObject *receiver, QEvent *e) {
-	if (QThread::currentThreadId() != _mainThreadId) {
-		return QApplication::notify(receiver, e);
-	}
+void Application::incrementEventNestingLevel() {
 	++_eventNestingLevel;
-	const auto result = QApplication::notify(receiver, e);
+}
+
+void Application::decrementEventNestingLevel() {
 	if (_eventNestingLevel == _loopNestingLevel) {
 		_loopNestingLevel = _previousLoopNestingLevels.back();
 		_previousLoopNestingLevels.pop_back();
@@ -429,7 +428,22 @@ bool Application::notify(QObject *receiver, QEvent *e) {
 	const auto processTillLevel = _eventNestingLevel - 1;
 	processPostponedCalls(processTillLevel);
 	_eventNestingLevel = processTillLevel;
-	return result;
+}
+
+void Application::registerEnterFromEventLoop() {
+	if (_eventNestingLevel > _loopNestingLevel) {
+		_previousLoopNestingLevels.push_back(_loopNestingLevel);
+		_loopNestingLevel = _eventNestingLevel;
+	}
+}
+
+bool Application::notify(QObject *receiver, QEvent *e) {
+	if (QThread::currentThreadId() != _mainThreadId) {
+		return QApplication::notify(receiver, e);
+	}
+
+	const auto wrap = createEventNestingLevel();
+	return QApplication::notify(receiver, e);
 }
 
 void Application::processPostponedCalls(int level) {
@@ -448,10 +462,7 @@ bool Application::nativeEventFilter(
 		const QByteArray &eventType,
 		void *message,
 		long *result) {
-	if (_eventNestingLevel > _loopNestingLevel) {
-		_previousLoopNestingLevels.push_back(_loopNestingLevel);
-		_loopNestingLevel = _eventNestingLevel;
-	}
+	registerEnterFromEventLoop();
 	return false;
 }
 

Telegram/SourceFiles/application.h

@@ -28,6 +28,11 @@ public:
 
 	void postponeCall(FnMut<void()> &&callable);
 	bool notify(QObject *receiver, QEvent *e) override;
+	void registerEnterFromEventLoop();
+	auto createEventNestingLevel() {
+		incrementEventNestingLevel();
+		return gsl::finally([=] { decrementEventNestingLevel(); });
+	}
 
 	void activateWindowDelayed(not_null<QWidget*> widget);
 	void pauseDelayedWindowActivations();
@@ -65,6 +70,8 @@ private:
 		FnMut<void()> callable;
 	};
 
+	void incrementEventNestingLevel();
+	void decrementEventNestingLevel();
 	bool nativeEventFilter(
 		const QByteArray &eventType,
 		void *message,

Telegram/SourceFiles/core/main_queue_processor.cpp

@@ -7,6 +7,8 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 */
 #include "core/main_queue_processor.h"
 
+#include "application.h"
+
 namespace Core {
 namespace {
 
@@ -38,15 +40,6 @@ void ProcessorEvent::process() {
 	_callable(_argument);
 }
 
-void ProcessMainQueue(void (*callable)(void*), void *argument) {
-	QMutexLocker lock(&ProcessorMutex);
-
-	if (ProcessorInstance) {
-		const auto event = new ProcessorEvent(callable, argument);
-		QCoreApplication::postEvent(ProcessorInstance, event);
-	}
-}
-
 void ProcessObservables() {
 	Global::RefHandleObservables().call();
 }
@@ -55,7 +48,20 @@ void ProcessObservables() {
 
 MainQueueProcessor::MainQueueProcessor() {
 	acquire();
-	crl::init_main_queue(ProcessMainQueue);
+
+	crl::init_main_queue([](void (*callable)(void*), void *argument) {
+		QMutexLocker lock(&ProcessorMutex);
+
+		if (ProcessorInstance) {
+			const auto event = new ProcessorEvent(callable, argument);
+			QCoreApplication::postEvent(ProcessorInstance, event);
+		}
+	});
+	crl::wrap_main_queue([](void (*callable)(void*), void *argument) {
+		App().registerEnterFromEventLoop();
+		const auto wrap = App().createEventNestingLevel();
+		callable(argument);
+	});
 
 	base::InitObservables(ProcessObservables);
 }