Details
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Bug
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Resolution: Unresolved
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P1: Critical
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None
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6.5.1
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None
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Windows 10 Enterprise, 22H2
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Windows
Description
While trying to print with QPrinter on Windows 10 22H2, the program crashes with:
ASSERT: "!isEmpty()" in file [...]/qtbase/src/corelib/tools/qliste.h, line 607
This is due to the following code bit:
QDataStream &operator<<(QDataStream &s, const QFont &font) { if (s.version() == 1) { s << font.d->request.families.first().toLatin1(); } else { s << font.d->request.families.first(); // crashes here [...] }
The call to first() crashes if families is empty. I suppose this is an illegal state for QFont to be in though - I'm not quite sure how this happens though. I'm not sure if I'm just missing some font on my Windows install, this is just a stock install. This happens while calling QPainter::begin(), so I don't think it has loaded the document yet, so maybe it's not actually due to missing fonts though?
Here's the code:
class Printer : QPrinter {[...]}; void Printer::print() { this->setDocName("Untitled"); this->setColorMode(this->config.chromaticity); this->setPageOrientation(this->config.orientation); this->setCopyCount(this->config.copies); this->setDuplex(this->config.side); this->setResolution(300); this->setPrinterName(printerInfo->printerName()); if (!this->isValid()) { throw PrintException(); } QPainter painter; if(!painter.begin(this)) { // crashes here throw PrintException(); } }
And here's the backtrace, tested with both the Conan package and the official Qt package.
Qt6Cored.dll!qt_message_fatal(QtMsgType __formal, const QMessageLogContext & context, const QString & message) Line 2042 (c:\Users\vagrant\.conan2\p\qtaabfba1f9d5d7\s\src\qtbase\src\corelib\global\qlogging.cpp:2042) Qt6Cored.dll!QMessageLogger::fatal(const char * msg, ...) Line 935 (c:\Users\vagrant\.conan2\p\qtaabfba1f9d5d7\s\src\qtbase\src\corelib\global\qlogging.cpp:935) Qt6Cored.dll!qt_assert(const char * assertion, const char * file, int line) Line 67 (c:\Users\vagrant\.conan2\p\qtaabfba1f9d5d7\s\src\qtbase\src\corelib\global\qassert.cpp:67) Qt6Guid.dll!QList<QString>::first() Line 607 (c:\Users\vagrant\.conan2\p\qtaabfba1f9d5d7\s\src\qtbase\src\corelib\tools\qlist.h:607) Qt6Guid.dll!operator<<(QDataStream & s, const QFont & font) Line 2290 (c:\Users\vagrant\.conan2\p\qtaabfba1f9d5d7\s\src\qtbase\src\gui\text\qfont.cpp:2290) Qt6Guid.dll!QPicturePaintEngine::updateFont(const QFont & font) Line 216 (c:\Users\vagrant\.conan2\p\qtaabfba1f9d5d7\s\src\qtbase\src\gui\image\qpaintengine_pic.cpp:216) Qt6Guid.dll!QPicturePaintEngine::updateState(const QPaintEngineState & state) Line 489 (c:\Users\vagrant\.conan2\p\qtaabfba1f9d5d7\s\src\qtbase\src\gui\image\qpaintengine_pic.cpp:489) Qt6Guid.dll!QPaintEngine::syncState() Line 272 (c:\Users\vagrant\.conan2\p\qtaabfba1f9d5d7\s\src\qtbase\src\gui\painting\qpaintengine.cpp:272) Qt6PrintSupportd.dll!QAlphaPaintEngine::flushAndInit(bool init) Line 330 (c:\Users\vagrant\.conan2\p\qtaabfba1f9d5d7\s\src\qtbase\src\printsupport\kernel\qpaintengine_alpha.cpp:330) Qt6PrintSupportd.dll!QAlphaPaintEngine::begin(QPaintDevice * pdev) Line 57 (c:\Users\vagrant\.conan2\p\qtaabfba1f9d5d7\s\src\qtbase\src\printsupport\kernel\qpaintengine_alpha.cpp:57) Qt6PrintSupportd.dll!QWin32PrintEngine::begin(QPaintDevice * pdev) Line 81 (c:\Users\vagrant\.conan2\p\qtaabfba1f9d5d7\s\src\qtbase\src\printsupport\platform\windows\qprintengine_win.cpp:81) Qt6Guid.dll!QPainter::begin(QPaintDevice * pd) Line 1790 (c:\Users\vagrant\.conan2\p\qtaabfba1f9d5d7\s\src\qtbase\src\gui\painting\qpainter.cpp:1790) print.exe!libprint::PrintOrder::print() Line 126 (c:\Users\vagrant\Projects\ds4-print-server-qt\src\PrintOrder.cpp:126) print.exe!libprint::WebsocketClient::executePrintOrder(const std::shared_ptr<libprint::PrintOrder> & order) Line 88 (c:\Users\vagrant\Projects\ds4-print-server-qt\src\WebSocketClient.cpp:88) print.exe!libprint::WebsocketClient::onTextMessageReceived(const QString & message) Line 64 (c:\Users\vagrant\Projects\ds4-print-server-qt\src\WebSocketClient.cpp:64) print.exe!QtPrivate::FunctorCall<QtPrivate::IndexesList<0>,QtPrivate::List<QString const &>,void,void (__cdecl libprint::WebsocketClient::*)(QString const &)>::call(void(libprint::WebsocketClient::*)(const QString &) f, libprint::WebsocketClient * o, void * * arg) Line 135 (c:\Users\vagrant\.conan2\p\b\qtfce70b96b2bba\p\include\QtCore\qobjectdefs_impl.h:135) print.exe!QtPrivate::FunctionPointer<void (__cdecl libprint::WebsocketClient::*)(QString const &)>::call<QtPrivate::List<QString const &>,void>(void(libprint::WebsocketClient::*)(const QString &) f, libprint::WebsocketClient * o, void * * arg) Line 173 (c:\Users\vagrant\.conan2\p\b\qtfce70b96b2bba\p\include\QtCore\qobjectdefs_impl.h:173) print.exe!QtPrivate::QSlotObject<void (__cdecl libprint::WebsocketClient::*)(QString const &),QtPrivate::List<QString const &>,void>::impl(int which, QtPrivate::QSlotObjectBase * this_, QObject * r, void * * a, bool * ret) Line 385 (c:\Users\vagrant\.conan2\p\b\qtfce70b96b2bba\p\include\QtCore\qobjectdefs_impl.h:385) Qt6Cored.dll!QtPrivate::QSlotObjectBase::call(QObject * r, void * * a) Line 363 (c:\Users\vagrant\.conan2\p\qtaabfba1f9d5d7\s\src\qtbase\src\corelib\kernel\qobjectdefs_impl.h:363) Qt6Cored.dll!doActivate<0>(QObject * sender, int signal_index, void * * argv) Line 3992 (c:\Users\vagrant\.conan2\p\qtaabfba1f9d5d7\s\src\qtbase\src\corelib\kernel\qobject.cpp:3992)