QTest QMainWindow and deleteLater

[wasawi2]

Hello everyone,

I am testing a QMainWindow and I am unable to delete it. I have tried everything, but whatever i do, if i try to delete it the test will run into segmentation fault. My main window has several widgets in it and it destroys itself as follows:

CMainWindow::~CMainWindow ( )
{
	model_->BaseModel::StopRefresher( );

	disconnect( model_, &CModel3D::OnLoggOut,      this, &CMainWindow::OnLoggedOut );
	disconnect( model_, &CModel3D::OnClose,        this, &CMainWindow::OnExit );

	if ( nullptr != model_ )
	{
		model_->deleteLater( );
	}

	if ( nullptr != lapView_ )
	{
		lapView_->deleteLater( );
	}

	if ( nullptr != stack_ )
	{
		stack_->deleteLater( );
	}

	if ( nullptr != view_ )
	{
		view_->deleteLater( );
	}
}

here is my cleanup function, but as I say I haven't found a way to safely destroy the window.

void MainWindowTest::cleanup ( )
{
//	QCoreApplication::sendPostedEvents(0, QEvent::DeferredDelete);
//	QCoreApplication::sendPostedEvents(0, -1);
//	QCoreApplication::processEvents();
//	mainWindow_instance->close();
//	mainWindow_instance->deleteLater( );

	delete mainWindow_instance;

//	QCoreApplication::sendPostedEvents(0, -1);
//	QCoreApplication::processEvents();
	QTest::qWait(250);
}

As you can see i have tried to allow the event loop to process the deleteLater with things like QCoreApplication::sendPostedEvents, QCoreApplication::processEvents, QTest::qWait... but without luck.

it seems QT is trying to delete a shared pointer after finishing to run the destructor. Here is a gdb print out:

Thread 1 "" hit Breakpoint 4, CMainWindow::~CMainWindow (this=0x907f090, __in_chrg=<optimized out>) at /XXX/mainwindow.cpp:110
110             if ( nullptr != view_ )
(gdb) s
113                     view_->deleteLater( );
(gdb) s
82      CMainWindow::~CMainWindow ( )
(gdb) s
QSharedPointer<QQuickItemGrabResult>::~QSharedPointer (this=0x907f0f0, __in_chrg=<optimized out>)
    at ../XXX/include/QtCore/qsharedpointer_impl.h:316
316         ~QSharedPointer() { deref(); }
(gdb) s
QSharedPointer<QQuickItemGrabResult>::deref (this=0x907f0f0) at ../XXX/include/QtCore/qsharedpointer_impl.h:459
459         { deref(d); }
(gdb) s
QSharedPointer<QQuickItemGrabResult>::deref (dd=0x0) at ../XXX/include/QtCore/qsharedpointer_impl.h:462
462             if (!dd) return;
(gdb) s
468         }
(gdb) s
 
Thread 1 "" received signal SIGSEGV, Segmentation fault.
sem_close (sem=0x0) at /builds/workspace/QOS224-SDP/build_x86_64/lib/c/1b/sem_close.c:26
26      /builds/workspace/QOS224-SDP/build_x86_64/lib/c/1b/sem_close.c: No such file or directory.

Does anyone know what might be going on? it seems to me that it is crashing on QT side.. not in my side.

Thanks in advance!
w

[JonB]

@wasawi2 said in QTest QMainWindow and deleteLater:

QSharedPointer<QQuickItemGrabResult>

If we are to believe this it would be to do with QtQuick/QML, which i would not have thought would be going on if you have a widgets application. You're not using any QtQuick/QML anywhere, are you?

[wasawi2]

Thank you @JonB,

Yes I am using QML. do you think it should be related to not being able to destroy some QML object?

[JonB]

@wasawi2
Well yes, in the sense that you can see what the output tells you, it's some shared pointer of a QQuickItemGrabResult, which you can look up.

I know nothing about QML so I can't help further, but that is the object in question for this error.

[wasawi2]

@JonB thank you so much. That was right.

there was an object that was calling deleteLater in different places and that caused a crash.

It was definitelly on my side.

Thanks!