Linux linker problems

[Perdrix]

When I rebuild my project this morning I got:

/usr/bin/ld: DeepSkyStacker/CMakeFiles/DeepSkyStacker.dir/StackingDlg.cpp.o: in function `ImageLoader::ImageLoader()':
/home/amonra/.vs/DSS/DeepSkyStacker/../DeepSkyStackerKernel/imageloader.h:66: undefined reference to `vtable for ImageLoader'
/usr/bin/ld: DeepSkyStacker/CMakeFiles/DeepSkyStacker.dir/StackingDlg.cpp.o: in function `ImageLoader::~ImageLoader()':
/home/amonra/.vs/DSS/DeepSkyStacker/../DeepSkyStackerKernel/imageloader.h:67: undefined reference to `vtable for ImageLoader'
/usr/bin/ld: DeepSkyStacker/CMakeFiles/DeepSkyStacker.dir/StackingDlg.cpp.o: in function `QMetaObject::Connection QObject::connect<void (ImageLoader::*)(std::filesystem::__cxx11::path), void (DSS::StackingDlg::*)(std::filesystem::__cxx11::path)>(QtPrivate::FunctionPointer<void (ImageLoader::*)(std::filesystem::__cxx11::path)>::Object const*, void (ImageLoader::*)(std::filesystem::__cxx11::path), QtPrivate::ContextTypeForFunctor<void (DSS::StackingDlg::*)(std::filesystem::__cxx11::path), void>::ContextType const*, void (DSS::StackingDlg::*&&)(std::filesystem::__cxx11::path), Qt::ConnectionType)':
/opt/Qt/6.8.0/gcc_64/include/QtCore/qobject.h:270: undefined reference to `ImageLoader::staticMetaObject'
/usr/bin/ld: DeepSkyStacker/CMakeFiles/DeepSkyStacker.dir/StackingDlg.cpp.o: in function `QMetaObject::Connection QObject::connect<void (ImageLoader::*)(), void (DSS::StackingDlg::*)()>(QtPrivate::FunctionPointer<void (ImageLoader::*)()>::Object const*, void (ImageLoader::*)(), QtPrivate::ContextTypeForFunctor<void (DSS::StackingDlg::*)(), void>::ContextType const*, void (DSS::StackingDlg::*&&)(), Qt::ConnectionType)':
/opt/Qt/6.8.0/gcc_64/include/QtCore/qobject.h:270: undefined reference to `ImageLoader::staticMetaObject'
/usr/bin/ld: DeepSkyStacker/CMakeFiles/DeepSkyStacker.dir/StackingDlg.cpp.o: in function `DSS::ImageListModel const* qobject_cast<DSS::ImageListModel const*>(QObject const*)':
/opt/Qt/6.8.0/gcc_64/include/QtCore/qobject.h:439: undefined reference to `DSS::ImageListModel::staticMetaObject'
/usr/bin/ld: DeepSkyStackerKernel/libDeepSkyStackerKernel.a(ImageListModel.cpp.o): in function `DSS::ImageListModel::ImageListModel(QObject*)':
/home/amonra/.vs/DSS/DeepSkyStackerKernel/ImageListModel.cpp:45: undefined reference to `vtable for DSS::ImageListModel'
/usr/bin/ld: DeepSkyStackerKernel/libDeepSkyStackerKernel.a(ImageListModel.cpp.o): in function `DSS::ImageListModel::tr(char const*, char const*, int)':
/home/amonra/.vs/DSS/DeepSkyStackerKernel/ImageListModel.h:43: undefined reference to `DSS::ImageListModel::staticMetaObject'
/usr/bin/ld: DeepSkyStackerKernel/libDeepSkyStackerKernel.a(imageloader.cpp.o): in function `ThreadLoader::ThreadLoader(std::filesystem::__cxx11::path const&, ImageLoader*)':
/home/amonra/.vs/DSS/DeepSkyStackerKernel/imageloader.h:87: undefined reference to `vtable for ThreadLoader'
/usr/bin/ld: /home/amonra/.vs/DSS/DeepSkyStackerKernel/imageloader.h:87: undefined reference to `vtable for ThreadLoader'
collect2: error: ld returned 1 exit status

I don't know if there's a Qt issue here or not, but does anyone recognise this problem (I'm using g++13 right now).

[JonB]

@Perdrix
Is ImageLoader a QObject? Does it generate signals? Did you remember to put in Q_OBJECT? Did you do a clean rebuild? Maybe same for DSS::ImageListModel?

[Perdrix]

The ImageLoader class ctor and dtor were declared "= default"

I changed that to simply declare in the header and actually created function bodies for them in the cpp file, but still getting complaints:

/usr/bin/ld: DeepSkyStacker/CMakeFiles/DeepSkyStacker.dir/StackingDlg.cpp.o: in function `QMetaObject::Connection QObject::connect<void (ImageLoader::*)(std::filesystem::__cxx11::path), void (DSS::StackingDlg::*)(std::filesystem::__cxx11::path)>(QtPrivate::FunctionPointer<void (ImageLoader::*)(std::filesystem::__cxx11::path)>::Object const*, void (ImageLoader::*)(std::filesystem::__cxx11::path), QtPrivate::ContextTypeForFunctor<void (DSS::StackingDlg::*)(std::filesystem::__cxx11::path), void>::ContextType const*, void (DSS::StackingDlg::*&&)(std::filesystem::__cxx11::path), Qt::ConnectionType)':
/opt/Qt/6.8.0/gcc_64/include/QtCore/qobject.h:270: undefined reference to `ImageLoader::staticMetaObject'
/usr/bin/ld: DeepSkyStacker/CMakeFiles/DeepSkyStacker.dir/StackingDlg.cpp.o: in function `QMetaObject::Connection QObject::connect<void (ImageLoader::*)(), void (DSS::StackingDlg::*)()>(QtPrivate::FunctionPointer<void (ImageLoader::*)()>::Object const*, void (ImageLoader::*)(), QtPrivate::ContextTypeForFunctor<void (DSS::StackingDlg::*)(), void>::ContextType const*, void (DSS::StackingDlg::*&&)(), Qt::ConnectionType)':
/opt/Qt/6.8.0/gcc_64/include/QtCore/qobject.h:270: undefined reference to `ImageLoader::staticMetaObject'
/usr/bin/ld: DeepSkyStacker/CMakeFiles/DeepSkyStacker.dir/StackingDlg.cpp.o: in function `DSS::ImageListModel const* qobject_cast<DSS::ImageListModel const*>(QObject const*)':
/opt/Qt/6.8.0/gcc_64/include/QtCore/qobject.h:439: undefined reference to `DSS::ImageListModel::staticMetaObject'
/usr/bin/ld: DeepSkyStackerKernel/libDeepSkyStackerKernel.a(ImageListModel.cpp.o): in function `DSS::ImageListModel::ImageListModel(QObject*)':
/home/amonra/.vs/DSS/DeepSkyStackerKernel/ImageListModel.cpp:45: undefined reference to `vtable for DSS::ImageListModel'
/usr/bin/ld: DeepSkyStackerKernel/libDeepSkyStackerKernel.a(ImageListModel.cpp.o): in function `DSS::ImageListModel::tr(char const*, char const*, int)':
/home/amonra/.vs/DSS/DeepSkyStackerKernel/ImageListModel.h:43: undefined reference to `DSS::ImageListModel::staticMetaObject'
/usr/bin/ld: DeepSkyStackerKernel/libDeepSkyStackerKernel.a(imageloader.cpp.o): in function `ImageLoader::ImageLoader()':
/home/amonra/.vs/DSS/DeepSkyStackerKernel/imageloader.cpp:30: undefined reference to `vtable for ImageLoader'
/usr/bin/ld: DeepSkyStackerKernel/libDeepSkyStackerKernel.a(imageloader.cpp.o): in function `ImageLoader::~ImageLoader()':
/home/amonra/.vs/DSS/DeepSkyStackerKernel/imageloader.cpp:32: undefined reference to `vtable for ImageLoader'
/usr/bin/ld: DeepSkyStackerKernel/libDeepSkyStackerKernel.a(imageloader.cpp.o): in function `ThreadLoader::ThreadLoader(std::filesystem::__cxx11::path const&, ImageLoader*)':
/home/amonra/.vs/DSS/DeepSkyStackerKernel/imageloader.h:87: undefined reference to `vtable for ThreadLoader'
/usr/bin/ld: /home/amonra/.vs/DSS/DeepSkyStackerKernel/imageloader.h:87: undefined reference to `vtable for ThreadLoader'

[jsulm]

@Perdrix Can you please answer all questions from @JonB ?

[JoeCFD]

This post is deleted!

[Perdrix]

Well yes, of course I will - I only just saw the questions

class ImageLoader : public QObject
{
	using CacheKeyType = std::filesystem::path;
	using CacheValueType = std::tuple<LoadedImage, int, bool>; // <image, lastUse, currentlyLoading>
	using CacheType = std::unordered_map<CacheKeyType, CacheValueType>;

	friend class ThreadLoader;
	Q_OBJECT

Yes, it generates signals.

Yes, I did a clean build

    class ImageListModel :
        public QAbstractTableModel
    {
        Q_OBJECT

It also emits signals

[jsulm]

This post is deleted!

[Perdrix]

Hmmm....

Looking at the static library that contains the object files for both those classes showed no sign of moc generated stuff!

I added set(CMAKE_AUTOMOC TRUE) at the top of the CMakeLists.txt file for the library and it worked. I'm a bit surprised that this isn't the default for qt_add_library

I also moved the Q_OBJECT macro (which didn't fix the problem) ...

David

[JoeCFD]

My code is as the follows and works.

class ImageLoader : public QObject
{
	Q_OBJECT

	friend class ThreadLoader;

It is the key to delete everything in the build dir and run cmake .. again. make clean is not enough.