[SOLVED] Force cmake to use gcc/mingw makefiles on Windows runner

[fangq]

I use github action to build a binary Python module. It works by calling python setup.py bdist_wheel in the action script, and setup.py calls cmake to build the module on different platforms. I have trouble forcing cmake to use mingw64-gcc as the compiler on Windows. it insists on using msvc to build my code (it can be compiled but the execution is incorrect).

I've spent a few days on this, tried a bunch of settings, all of them had failed, below link is a summary for some of my attempts, together with their error logs

#1621 (comment)

does gcc/mingw generator work on the windows runner image? what do I need to switch to it?

[fangq]

never mind. figured it out. it turns out one has to install ninja via msys2 before one can set -GNinja with cmake.

although cmake -G lists Ninja, it does not mean the system has ninja system installed, it just means it can work with it. this is why I thought all generators in the printed list have already been installed.

I managed to use the setting from
https://github.com/scivision/rpn-calc-fortran/blob/main/.github/workflows/ci_cmake.yml

specifically

    - uses: msys2/setup-msys2@v2
      with:
        update: true
        install: >-
          mingw-w64-x86_64-ninja

    - name: Put MSYS2_MinGW64 on PATH
      run: echo "D:/a/_temp/msys64/mingw64/bin" >> $GITHUB_PATH

presumably, one could also use other packages to install ninja as well.

anyways, once ninja is added, after passing -GNinja to cmake, it finds mingw64 gcc and build the binaries without any problem.