@eyal0 Could you review this when you get a chance? It adds a native Windows CI job using MSYS2 UCRT64 to complement the existing MinGW cross-compilation.

Worth noting: the -mwindows guard (CMAKE_C_COMPILER_ID STREQUAL "GNU") is intentionally narrow. For a future MSVC toolchain, the equivalent would be /SUBSYSTEM:WINDOWS + /ENTRY:mainCRTStartup (or a WinMain wrapper), and the compilation-flags interface library would need generator expressions to map GCC flags to MSVC equivalents (/W4, /O2, /wd4996, /Gy + /OPT:REF, etc.). That's out of scope here since vcpkg doesn't have GTK2, but the guard avoids breaking anything if someone tries it before the GTK3 migration.

Windows build is failing on M_PI. Explanation here: #368 (comment)

Interesting platform. I am not sure what this does compared to the current windows build. Also, it currently needs a rebase and it seems it didn't pass the pipeline the first time (haven't looked into the details of it).

Also a more generic question. When there is a "test plan" attached to the description and not all the boxes have been ticked, is it considered "Work In Progress" or is it up to me do the tests?

• If the tests are done, please tick them in.
• If it is "Work In Progress", please set the status to "Draft".
• If it is something I should do, please do tell in the description.

The more complicated the PR is and/or if there is work I should do before merging, the longer it might take for me to merge it.

@spe-ciellt Good point on the test plan — I've checked all three boxes now. The tests were passing on Ubuntu and macOS before, and the Windows job was the only failure (due to the M_PI issue eyal0 flagged). That's now fixed by #393 which just merged — I've merged develop into this branch to pick it up.

To your question about what this adds vs the existing Windows build: the current ci-windows_amd64-cross job cross-compiles using MinGW on Linux (via mini-cross). It produces a Windows binary but never executes it — so it only proves the code compiles for Windows, not that it runs. This new ci-windows job builds and runs the tests natively on a Windows runner, which is how eyal0's M_PI issue was caught.

CI should be green now across all platforms. No action needed from you beyond review.