Windows下使用LLVM与MinGW编译链接OpenCV时出现错误

环境配置 #

• 系统：Windows
• 工具链：从LLVM官网获取的LLVM，从mingw-builds-binaries获取的MinGW
• bash环境中设置的变量：

export CC="clang.exe -target x86_64-pc-windows-gnu"
export CXX="clang++.exe -target x86_64-pc-windows-gnu"
export CMAKE_GENERATOR="MinGW Makefiles"

注：不给clang添加-target参数时，用MSVC可正常编译

链接阶段报错：pthread符号未定义 #

编译过程前9%正常，到链接libopencv_core460.dll时终止，输出如下：

[  9%] Building CXX object modules/core/CMakeFiles/opencv_core.dir/split.avx2.cpp.obj
[  9%] Building CXX object modules/core/CMakeFiles/opencv_core.dir/sum.avx2.cpp.obj
[  9%] Building CXX object modules/core/CMakeFiles/opencv_core.dir/matmul.avx512_skx.cpp.obj
[  9%] Building RC object modules/core/CMakeFiles/opencv_core.dir/vs_version.rc.obj
[  9%] Linking CXX shared library ..\..\bin\libopencv_core460.dll

伴随大量pthread相关未定义引用错误，示例：

C:\Users\akar\bin\mingw\mingw64\bin\ld.exe: CMakeFiles\opencv_core.dir/objects.a(system.cpp.obj):system.cpp:(.text$_ZN2cv5errorERKNS_9ExceptionE[_ZN2cv5errorERKNS_9ExceptionE]+0x34): undefined reference to `pthread_mutex_lock'
C:\Users\akar\bin\mingw\mingw64\bin\ld.exe: CMakeFiles\opencv_core.dir/objects.a(system.cpp.obj):system.cpp:(.text$_ZN2cv5errorERKNS_9ExceptionE[_ZN2cv5errorERKNS_9ExceptionE]+0xc5): undefined reference to `pthread_mutex_unlock'
C:\Users\akar\bin\mingw\mingw64\bin\ld.exe: CMakeFiles\opencv_core.dir/objects.a(system.cpp.obj):system.cpp:(.text$_ZN2cv5errorERKNS_9ExceptionE[_ZN2cv5errorERKNS_9ExceptionE]+0x176): undefined reference to `pthread_mutex_unlock'

修改链接器后出现标准库错误 #

尝试通过设置alias让链接器默认链接pthread：

alias ld="ld -lpthread"

编译时出现新错误：

C:/Users/akar/source/repos/opencv/modules/core/include\opencv2/core/utility.hpp:718:9: error: no type named 'recursive_mutex' in namespace 'std'; did you mean '__gnu_cxx::__recursive_mutex'?
typedef std::recursive_mutex Mutex;
        ^~~~~~~~~~~~~~~~~~~~
        __gnu_cxx::__recursive_mutex
C:\Users\akar\bin\mingw\mingw64\lib\gcc\x86_64-w64-mingw32\12.1.0\include\c++\ext/concurrence.h:170:9: note: '__gnu_cxx::__recursive_mutex' declared here
  class __recursive_mutex
        ^
1 error generated.

内容的提问来源于stack exchange，提问作者msmechanized