Consider creating a CI runner for MinGW

[ahayzen-kdab]

• Create separate CI runner for MinGW Qt5 and Qt6
• Only enable MSVC prompt for MSVC rather than "Windows"
• Install MinGW in the CI runner
• Find out if the tests run correctly and fix any broken ones

[ahayzen-kdab]

@Be-ing any ideas how easy this might or might not be ?

Looks like this would need to be adjusted to be only msvc

    # Required for CMake to find Ninja
    - name: "[Windows] Set up MSVC Developer Command Prompt"
      if: runner.os == 'Windows'
      uses: seanmiddleditch/gha-setup-vsdevenv@v3

And we would need a new block here which doesn't use cl ?

          - name: Windows 2022 (MSVC) Qt6
            os: windows-2022
            qt_version: 6
            ctest_args: --exclude-regex '^(reuse_lint|cpp_clang_format|.*valgrind)$'
            exe_suffix: .exe
            qt_qpa_platform: windows
            compiler_cache_path: C:\Users\runneradmin\AppData\Local\Mozilla\sccache\cache
            cargo_dir: C:\Users\runneradmin\.cargo
            cc: cl
            cxx: cl
            # The D drive runs out of space when building dependencies with vcpkg.
            workspace: C:\cxx-qt

And we would need to install mingw from somewhere ? (would this be from vcpkg or is there a github action we can use or is it already installed?)

[Be-ing]

I do want to support MinGW, however, I'm a bit concerned about using 8 CI jobs on every commit 😵

[ahayzen-kdab]

@Be-ing I wonder if we only run certain runners on every commit, then have extra runners for either just main or just releases or something 🤷

I thought i had seen other projects that have some runners run initially in the pull request for each commit, then when things are approved before merging it runs all the tests - but maybe I'm dreaming :-)