QLineEdit + QUndoCommand::mergeWidth crashes App
-
Good question! The crash appeared on Qt5.7.1 in Ubuntu 16.04. So, I upgraded to Qt5.12.0.
What is rather annoying is that it is not completely clear under which circumstances the crash occurs. After trying several times, I got it to occur as follows: add numbers to the QLineEdit below 'Time' until the value automatically changes to scientific notation. Subsequently, undo and then perform a redo. But it seems better to play with it and perhaps restart the app so now and then to get to a crash. I am not sure how to save a stack trace, but below is something that I could copy from the debugger. In some cases, I got the following messages as application output:
07:31:04: Debugging starts OpenType support missing for "Ubuntu", script 11 OpenType support missing for "Ubuntu", script 9 OpenType support missing for "Ubuntu", script 13 OpenType support missing for "Ubuntu", script 17 07:37:26: Debugging has finished07:37:30: Starting undo_issue/build/debug/undo_issue... 07:37:37: The program has unexpectedly finished. 07:37:37: The process was ended forcefully. 07:37:37: build/debug/undo_issue crashed.1 QUndoCommand::actionText() const 0x7ffff7a34d20 2 QUndoStack::undoText() const 0x7ffff7a35241 3 QUndoStackPrivate::setIndex(int, bool) 0x7ffff7a3530d 4 QUndoStack::redo() 0x7ffff7a366fb 5 QMetaObject::activate(QObject *, int, int, void * *) 0x7ffff6873629 6 QAction::triggered(bool) 0x7ffff76e5882 7 QAction::activate(QAction::ActionEvent) 0x7ffff76e7ca0 8 QAbstractButtonPrivate::click() 0x7ffff77d3450 9 QAbstractButton::mouseReleaseEvent(QMouseEvent *) 0x7ffff77d3565 10 QToolButton::mouseReleaseEvent(QMouseEvent *) 0x7ffff78b192a 11 QWidget::event(QEvent *) 0x7ffff7729348 12 QToolButton::event(QEvent *) 0x7ffff78b19f9 13 QApplicationPrivate::notify_helper(QObject *, QEvent *) 0x7ffff76eb85c 14 QApplication::notify(QObject *, QEvent *) 0x7ffff76f2fcf 15 QCoreApplication::notifyInternal2(QObject *, QEvent *) 0x7ffff6847c18 16 QApplicationPrivate::sendMouseEvent(QWidget *, QMouseEvent *, QWidget *, QWidget *, QWidget * *, QPointer<QWidget>&, bool, bool) 0x7ffff76f1f0a 17 QWidgetWindow::handleMouseEvent(QMouseEvent *) 0x7ffff7742d4b 18 QWidgetWindow::event(QEvent *) 0x7ffff774586b 19 QApplicationPrivate::notify_helper(QObject *, QEvent *) 0x7ffff76eb85c 20 QApplication::notify(QObject *, QEvent *) 0x7ffff76f29f0 21 QCoreApplication::notifyInternal2(QObject *, QEvent *) 0x7ffff6847c18 22 QGuiApplicationPrivate::processMouseEvent(QWindowSystemInterfacePrivate::MouseEvent *) 0x7ffff6eb01e7 23 QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent *) 0x7ffff6eb1795 24 QWindowSystemInterface::sendWindowSystemEvents(QFlags<QEventLoop::ProcessEventsFlag>) 0x7ffff6e8d44b 25 xcbSourceDispatch(_GSource *, int ( *)(void *), void *) 0x7fffef89c67a 26 g_main_context_dispatch 0x7ffff29c3197 27 ?? 0x7ffff29c33f0 28 g_main_context_iteration 0x7ffff29c349c 29 QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) 0x7ffff689edcf 30 QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) 0x7ffff684657a 31 QCoreApplication::exec() 0x7ffff684ef80 32 main main.cpp 10 0x4046c2 -
Well, was able to get a glimpse of some strange behavior and after hitting 'Undo' a crash. The screenshot before hitting 'Undo' and the applocation output (this was unfortunately not done in the debugger). I am slowly starting to think that the call to QObject::tr in my QUndoCommand constructors are causing the problem...
The example app can be downloaded from https://modeltech.org/temp/undo_issue.zip
Application Output:
09:30:52: Starting undo_issue/build/debug/undo_issue... OpenType support missing for "Ubuntu", script 18 OpenType support missing for "Ubuntu", script 10 OpenType support missing for "Ubuntu", script 17 OpenType support missing for "Ubuntu", script 15 09:32:31: The program has unexpectedly finished. 09:32:31: The process was ended forcefully. 09:32:31: undo_issue/build/debug/undo_issue crashed. -
After removing the QObject::tr calls, it still crashes, but now the stack trace looks a bit different. I am not aware of a method isObsolete for QUndoCommand but it seems that there is a problem with that :?
1 QUndoCommand::isObsolete() const 0x7ffff7a34ce4 2 QUndoStack::undo() 0x7ffff7a361db 3 QMetaObject::activate(QObject *, int, int, void * *) 0x7ffff6873629 4 QAction::triggered(bool) 0x7ffff76e5882 5 QAction::activate(QAction::ActionEvent) 0x7ffff76e7ca0 6 QAbstractButtonPrivate::click() 0x7ffff77d3450 7 QAbstractButton::mouseReleaseEvent(QMouseEvent *) 0x7ffff77d3565 8 QToolButton::mouseReleaseEvent(QMouseEvent *) 0x7ffff78b192a 9 QWidget::event(QEvent *) 0x7ffff7729348 10 QToolButton::event(QEvent *) 0x7ffff78b19f9 11 QApplicationPrivate::notify_helper(QObject *, QEvent *) 0x7ffff76eb85c 12 QApplication::notify(QObject *, QEvent *) 0x7ffff76f2fcf 13 QCoreApplication::notifyInternal2(QObject *, QEvent *) 0x7ffff6847c18 14 QApplicationPrivate::sendMouseEvent(QWidget *, QMouseEvent *, QWidget *, QWidget *, QWidget * *, QPointer<QWidget>&, bool, bool) 0x7ffff76f1f0a 15 QWidgetWindow::handleMouseEvent(QMouseEvent *) 0x7ffff7742d4b 16 QWidgetWindow::event(QEvent *) 0x7ffff774586b 17 QApplicationPrivate::notify_helper(QObject *, QEvent *) 0x7ffff76eb85c 18 QApplication::notify(QObject *, QEvent *) 0x7ffff76f29f0 19 QCoreApplication::notifyInternal2(QObject *, QEvent *) 0x7ffff6847c18 20 QGuiApplicationPrivate::processMouseEvent(QWindowSystemInterfacePrivate::MouseEvent *) 0x7ffff6eb01e7 21 QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent *) 0x7ffff6eb1795 22 QWindowSystemInterface::sendWindowSystemEvents(QFlags<QEventLoop::ProcessEventsFlag>) 0x7ffff6e8d44b 23 xcbSourceDispatch(_GSource *, int ( *)(void *), void *) 0x7fffef89c67a 24 g_main_context_dispatch 0x7ffff29c3197 25 ?? 0x7ffff29c33f0 26 g_main_context_iteration 0x7ffff29c349c 27 QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) 0x7ffff689edeb 28 QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) 0x7ffff684657a 29 QCoreApplication::exec() 0x7ffff684ef80 30 main main.cpp 10 0x4046b2 -
After completely removing the setText calls in the QUndoCommand, I still have a crash, now with yet another stack trace
1 __memmove_ssse3_back memcpy-ssse3-back.S 1544 0x7ffff5dd7e2f 2 QListData::remove(int) 0x7ffff66dbcc4 3 QUndoStack::undo() 0x7ffff7a36244 4 QMetaObject::activate(QObject *, int, int, void * *) 0x7ffff6873629 5 QAction::triggered(bool) 0x7ffff76e5882 6 QAction::activate(QAction::ActionEvent) 0x7ffff76e7ca0 7 QAbstractButtonPrivate::click() 0x7ffff77d3450 8 QAbstractButton::mouseReleaseEvent(QMouseEvent *) 0x7ffff77d3565 9 QToolButton::mouseReleaseEvent(QMouseEvent *) 0x7ffff78b192a 10 QWidget::event(QEvent *) 0x7ffff7729348 11 QToolButton::event(QEvent *) 0x7ffff78b19f9 12 QApplicationPrivate::notify_helper(QObject *, QEvent *) 0x7ffff76eb85c 13 QApplication::notify(QObject *, QEvent *) 0x7ffff76f2fcf 14 QCoreApplication::notifyInternal2(QObject *, QEvent *) 0x7ffff6847c18 15 QApplicationPrivate::sendMouseEvent(QWidget *, QMouseEvent *, QWidget *, QWidget *, QWidget * *, QPointer<QWidget>&, bool, bool) 0x7ffff76f1f0a 16 QWidgetWindow::handleMouseEvent(QMouseEvent *) 0x7ffff7742d4b 17 QWidgetWindow::event(QEvent *) 0x7ffff774586b 18 QApplicationPrivate::notify_helper(QObject *, QEvent *) 0x7ffff76eb85c 19 QApplication::notify(QObject *, QEvent *) 0x7ffff76f29f0 20 QCoreApplication::notifyInternal2(QObject *, QEvent *) 0x7ffff6847c18 21 QGuiApplicationPrivate::processMouseEvent(QWindowSystemInterfacePrivate::MouseEvent *) 0x7ffff6eb01e7 22 QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent *) 0x7ffff6eb1795 23 QWindowSystemInterface::sendWindowSystemEvents(QFlags<QEventLoop::ProcessEventsFlag>) 0x7ffff6e8d44b 24 xcbSourceDispatch(_GSource *, int ( *)(void *), void *) 0x7fffef89c67a 25 g_main_context_dispatch 0x7ffff29c3197 26 ?? 0x7ffff29c33f0 27 g_main_context_iteration 0x7ffff29c349c 28 QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) 0x7ffff689edcf 29 QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) 0x7ffff684657a 30 QCoreApplication::exec() 0x7ffff684ef80 31 main main.cpp 10 0x404642 -
You should try to create a minimal, compilable example so we can try to reproduce it. Or even better you'll find your problem while trying to create the example.
Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
Visit the Qt Academy at https://academy.qt.io/catalog -
You should try to create a minimal, compilable example so we can try to reproduce it. Or even better you'll find your problem while trying to create the example.
@Christian-Ehrlicher I actually did create one, but apparently I forgot to post the link... So, here it is https://modeltech.org/temp/undo_issue.zip
-
Your testapp works fine here with Qt5.11.2 on Linux. Is there something special I've to do?
-
It's also working with 5.12 / 64 bit.
