Qt 5.12 crashing intermittently on Mac - update
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I posted about intermittent crashes on the Mac previously.
The crash always happens here:
0 org.qt-project.QtCore 0x000000010d138fe8 QMetaObject::cast(QObject*) const + 24 1 org.qt-project.QtWidgets 0x000000010c47674b QWidget::isActiveWindow() const + 283 2 org.qt-project.QtWidgets 0x000000010c486aad QWidget::initPainter(QPainter*) const + 45 3 org.qt-project.QtGui 0x000000010cc508dd QPainter::begin(QPaintDevice*) + 781 4 org.qt-project.QtGui 0x000000010cc505c2 QPainter::QPainter(QPaintDevice*) + 242 5 org.qt-project.QtWidgets 0x000000010c479937 QWidgetPrivate::drawWidget(QPaintDevice*, QRegion constIt happened in Qt 5.12.0 to 5.12.2. Updating to Qt 5.12.3 and 5.12.4 didn't fix it.
The crash didn't happen in Qt 5.11.0, but that has other issues and I wanted to upgrade to a newer version.
On the couple of time I managed to get it to happen it seems that a QEvent was being passed to QMainWindow::event() of type QEvent::UpdateRequest with a null QEvent::d member. Presumably that null was causing the crash when it was cast further down.
I couldn't reproduce the crash reliably until I saw that this bug fix in 5.12.5:
https://bugreports.qt.io/browse/QTBUG-76588To reproduce the crash:
-open a modal dialog
-open another modal dialog from the first modal dialog
-close the second modal dialog
-close the first modal dialog using the small red close button at the top of the window (not one of the buttons at the bottom)This causes a crash with the stack trace above. Upgrading to 5.12.5 fixes it.
The bug fix says it is a regression since 5.12.4. But I was having this crash back to Qt 5.12.0. So I don't know if there are other ways to cause a crash with the same track trace that won't be fixed by the new Qt version. I will have to see if I get further reports of crashes from users with the same stack trace.
I hope this information might be useful to someone else.
If anyone has any further information on this issue, please let me know.
