Build Windows Wheel in MSYS2 UCRT64 Environment?

[scott-guthridge]

Our Cython project makes heavy use of C99 complex. The native Windows environment with MSVC, however, uses the struct-based _Dcomplex and friends types which are binary compatible, but not source compatible, with C's complex. Cython doesn't seem to automatically convert its generated code to the Windows style complex types. My question is: is it possible to get cibuildwheel to run the make wheel step in the MSYS2 UCRT64 environment? [In this environment, C complex is handled normally (using gcc) yet the resulting binaries are still native windows compatible.] If so, how do you do it?

[scott-guthridge]

To answer my own question, it is possible. The key is to first set up the MSYS2 environment with UCRT64 system. Using UCRT64 builds real Windows libraries (that can be used inside or outside of the MSYS environment). Then in the next block, the shell: msys2 {0} line starts a shell where you can do the build in a POSIX-like environment.

    - name: Setup MSYS2 (Windows)
      if: ${{ runner.os == 'Windows' }}
      uses: msys2/setup-msys2@v2
      with:
        msystem: UCRT64
        update: true
        install: mingw-w64-ucrt-${{matrix.buildplat.arch}}-gcc
                 mingw-w64-ucrt-${{matrix.buildplat.arch}}-ghostscript
                 mingw-w64-ucrt-${{matrix.buildplat.arch}}-libyaml
                 autoconf automake git groff make libtool patch pkg-config zip
    - name: Build Libvna (Windows)
      if: ${{ runner.os == 'Windows' }}
      shell: msys2 {0}
      run: |
        ./bootstrap
        ./configure
        make pkg
        bash tools/make-windows-zip
        ls -l package/pkg
    - name: Upload Artifacts (Windows)
      if: ${{ runner.os == 'Windows' }}
      uses: actions/upload-artifact@v4
      with:
        name: ${{ matrix.buildplat.sys }}-${{ matrix.buildplat.arch }}
        path: |
            package/pkg/libvna-*.pkg.tar.zst
            package/pkg/libvna-*-windows-*.zip

Complete example can be found in this repo: https://github.com/scott-guthridge/libvna/tree/master