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Thread: CMake, MinGw and failng linking

  1. #1
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    Default CMake, MinGw and failng linking

    Hi,
    I've downloaded and installed Qt5.5 precompiled with MinGw 4.92.
    After that I tried to compile my old projects (created with Qt for VisualStudio).
    This binary compiles - fails during linkage.
    Qt Code:
    1. || [ 42%] Built target log4cpp
    2. || [ 45%] Built target tools_lib
    3. || [ 46%] Automatic moc for target PhoneticNumberSystem
    4. || [ 46%] Built target PhoneticNumberSystem_automoc
    5. || [ 47%] Linking CXX executable PhoneticNumberSystem.exe
    6. || CMakeFiles\PhoneticNumberSystem.dir/objects.a(CAppSettings.cpp.obj):CAppSettings.cpp:(.text+0xd7c): undefined reference to `_imp___ZN7QObjectC2EPS_'
    7. || CMakeFiles\PhoneticNumberSystem.dir/objects.a(CAppSettings.cpp.obj):CAppSettings.cpp:(.text+0xe72): undefined reference to `_imp___ZN7QObjectD2Ev'
    8. || CMakeFiles\PhoneticNumberSystem.dir/objects.a(CAppSettings.cpp.obj):CAppSettings.cpp:(.text+0xebc): undefined reference to `_imp___ZN7QObjectD2Ev'
    9. || CMakeFiles\PhoneticNumberSystem.dir/objects.a(CDataThread.cpp.obj):CDataThread.cpp:(.text+0x1d3): undefined reference to `_imp___ZN4QDirC1ERK7QString'
    10. || CMakeFiles\PhoneticNumberSystem.dir/objects.a(CDataThread.cpp.obj):CDataThread.cpp:(.text+0x1f8): undefined reference to `_imp___ZN4QDirD1Ev'
    11. || CMakeFiles\PhoneticNumberSystem.dir/objects.a(CDataThread.cpp.obj):CDataThread.cpp:(.text+0x35f): undefined reference to `_imp___ZN4QDirD1Ev'
    12. || CMakeFiles\PhoneticNumberSystem.dir/objects.a(CDataThread.cpp.obj):CDataThread.cpp:(.text+0x500): undefined reference to `_imp___ZN4QDir9separatorEv'
    13. || CMakeFiles\PhoneticNumberSystem.dir/objects.a(CDataThread.cpp.obj):CDataThread.cpp:(.text+0x7a6): undefined reference to `_imp___ZN4QDir9separatorEv'
    To copy to clipboard, switch view to plain text mode 
    Here what CMakeLists.txt for main binary looks like http://pastebin.com/Bk5Jq0ZR
    g++ (GCC) 4.8.1
    In system environment I added variable QT_DIR=d:\Qt\Qt5.5.1\5.5\mingw492_32
    and added it to PATH like => %QT_DIR%;%QT_DIR%\bin;%QT_DIR%\include;%QT_DIR%\li b

    Obviously, linker can't find proper objects in proposed libraries. Now, should I rebuild entire Qt to fit G++ 4.8? Should I install more recent MinGw version with newer g++? Or some other CMake settings changes are needed?

  2. #2
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    Default Re: CMake, MinGw and failng linking

    Try to change environment var-name QT_DIR to QTDIR.

  3. #3
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    Default Re: CMake, MinGw and failng linking

    Didn't help.
    CMake finds Qt, as compilation is success. But it fails in linking with precompiled libraries.

  4. #4
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    Default Re: CMake, MinGw and failng linking

    It looks to me as though you might be missing a #define QT_DLL as part of your compilation and linking options. Look at your old VS project file and I think you'll find that. So it will need to be set for CMake as well via a compiler and linker -D flag most likely.

  5. #5
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    Default Re: CMake, MinGw and failng linking

    When I changed QT_DIR variable (and in result PATH) I didn't delete CMake build rules/cache. It didn't matter how many times I run cmake or make or make clean - inside Makefiles path to Qt libraries were leading to previously set MSVC folder.
    I've deleted build folder, generated it once again and this time binaries compiled and linked without a problem.
    Thank you all - case closed.

  6. #6
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    Default Re: CMake, MinGw and failng linking

    That is one of those CMake gotchas that you really have to watch out for. It burns me every time I'm starting a new CMake project and am still playing around with settings.

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