Failure by linking with Qt6 on F40

[1div0]

Describe the bug Linker command failed with following errors: cd YUViewApp/ && ( test -e Makefile || /bin/qmake6 -o Makefile /2TB/usr/src/github.com/IENT/YUView/YUViewApp/YUViewApp.pro -spec linux-clang-libc++ CONFIG+=debug ) && make -f Makefile make[1]: Entering directory '/2TB/usr/src/github.com/IENT/YUView/YUViewApp' clang++ -c -pipe -stdlib=libc++ -g -std=gnu++1z -Wall -Wextra -D_REENTRANT -DYUVIEW_VERSION=\"v2.14-70-g4b039328\" -DQT_WIDGETS_LIB -DQT_OPENGL_LIB -DQT_GUI_LIB -DQT_XML_LIB -DQT_CONCURRENT_LIB -DQT_NETWORK_LIB -DQT_CORE_LIB -I. -I../YUViewLib/src -I/usr/include/qt6 -I/usr/include/qt6/QtWidgets -I/usr/include/qt6/QtOpenGL -I/usr/include/qt6/QtGui -I/usr/include/qt6/QtXml -I/usr/include/qt6/QtConcurrent -I/usr/include/qt6/QtNetwork -I/usr/include/qt6/QtCore -I. -I/usr/lib64/qt6/mkspecs/linux-clang-libc++ -o yuviewapp.o src/yuviewapp.cpp clang++ -ccc-gcc-name g++ -stdlib=libc++ -Wl,-rpath-link,/usr/lib64 -o YUView yuviewapp.o -L/2TB/usr/src/github.com/IENT/YUView/YUViewLib -lYUViewLib /usr/lib64/libQt6Widgets.so /usr/lib64/libQt6OpenGL.so /usr/lib64/libQt6Gui.so /usr/lib64/libQt6Xml.so /usr/lib64/libQt6Concurrent.so /usr/lib64/libQt6Network.so /usr/lib64/libQt6Core.so -lpthread -lGLX -lOpenGL
/bin/ld: /2TB/usr/src/github.com/IENT/YUView/YUViewLib/libYUViewLib.a(Mainwindow.o): in function bool QMetaType::registerConverterImpl<std::__1::pair<int, int>, QtMetaTypePrivate::QPairVariantInterfaceImpl>(std::__1::function<bool (void const*, void*)>, QMetaType, QMetaType)': /usr/include/qt6/QtCore/qmetatype.h:652: undefined reference toQMetaType::registerConverterFunction(std::1::function<bool (void const, void)> const&, QMetaType, QMetaType)' /bin/ld: /2TB/usr/src/github.com/IENT/YUView/YUViewLib/libYUViewLib.a(PlaybackController.o): in function QBasicTimer::start(int, Qt::TimerType, QObject*)': /usr/include/qt6/QtCore/qbasictimer.h:54: undefined reference toQBasicTimer::start(std::1::chrono::duration<long long, std::__1::ratio<1l, 1000l> >, Qt::TimerType, QObject)' /bin/ld: /2TB/usr/src/github.com/IENT/YUView/YUViewLib/libYUViewLib.a(BitstreamAnalysisWidget.o): in function QtConcurrent::RunFunctionTaskBase<void>::run()': /usr/include/qt6/QtConcurrent/qtconcurrentrunbase.h:88: undefined reference toQUnhandledException::QUnhandledException(std::exception_ptr)' /bin/ld: /2TB/usr/src/github.com/IENT/YUView/YUViewLib/libYUViewLib.a(FFmpegVersionHandler.o): in function QString::toStdString() const': /usr/include/qt6/QtCore/qstring.h:1397: undefined reference toQByteArray::toStdString() const' /bin/ld: /2TB/usr/src/github.com/IENT/YUView/YUViewLib/libYUViewLib.a(playlistItemStatisticsFile.o): in function `QBasicTimer::start(int, QObject)': /usr/include/qt6/QtCore/qbasictimer.h:49: undefined reference to `QBasicTimer::start(std::1::chrono::duration<long long, std::1::ratio<1l, 1000l> >, QObject*)' clang++: error: linker command failed with exit code 1 (use -v to see invocation) make[1]: [Makefile:69: YUView] Error 1 make[1]: Leaving directory '/2TB/usr/src/github.com/IENT/YUView/YUViewApp' make: [Makefile:73: sub-YUViewApp-make_first] Error 2

qmake6 -spec linux-clang-libc++ CONFIG+=debug

Version (please complete the following information):

• OS: Fedora 40
• Version develop 2.3-1407-g4b039328
• If you compiled YUView yourself then which Qt version did you use? 6.7.2

[1div0]

With qmake-qt5 -spec linux-clang-libc++ CONFIG+=debug

compilation and linking succeeded.

[ChristianFeldmann]

I can confirm this. But it also only happens with clang. GCC also compiles correctly.

[ChristianFeldmann]

I am wondering if this is a bug in clang / Qt or if this is a change in Qt where clang is just more strict then GCC is. This is definitely super strange. I can see these things that are failing:

• QBasicTimer::start - There was a change in 6.5. Might be related.
• QByteArray::toStdString - I could not see a big change. The QString got a new constructor in 6.5 but no idea if this is realted.

[ChristianFeldmann]

Dockerfile to reproduce:

FROM fedora:40
RUN dnf install -y git qt6-qtbase-devel clang libcxx-devel

then run

qmake -spec linux-clang-libc++ ../../
make -j 12

[ChristianFeldmann]

So I was not able to track this down. For now my recommendation is, to compile with GCC. My best guess is, that something is not completely right with the type definitions in clang or how the defines are setup. For example, I could see that the QBasicTimer is now using std::chrono::milliseconds as a parameter. The type for this is defined as which is exactly what the linker is complaining about. So maybe the type here is defined differently for GCC? For GCC it looks like it is std::int64_t. Sorry but I will not further investigate this.

[1div0]

@ChristianFeldmann Thank you for all your efforts. I will try to dig deeper.