I somewhat forgot that NumPy hasn't yet moved, so this really needs to wait until GHA has proper runner support, and some of the lower ecosystem moves forward.

OK, while technically we recently dropped NumPy as a build requirement, this still fails because meson-python doesn't support cross-compiling. Apparently the macOS stuff was just a setuptools-specific thing that they also implemented, but more generic cross-compiling support is not really a standardized thing in the Python ecosystem, even if that's what cibuildwheel is trying to do here.

GitHub Actions now has native Windows-on-ARM runners: https://github.blog/changelog/2025-04-14-windows-arm64-hosted-runners-now-available-in-public-preview/

So this is now able to build, but I've had to skip testing right now because NumPy wheels are not available (see linked issue.)

NumPy wheels were just merged today. It looks like nightlies are uploaded Sunday and Wednesday mornings, so by next week we should be able to try testing this out.

Looks like the arm64 windows wheels are available for the numpy pre-release on pypi now.

Looks like we need to install the NumPy pre-release, but otherwise this does appear to work. It also builds contourpy from source, though without any error, so I will open a PR there to make wheels.

contourpy has a bit of a bootstrap problem of us not having wheels and we seem to be okay building theirs without testing, so I'll mark this ready.

contourpy has a bit of a bootstrap problem of us not having wheels and we seem to be okay building theirs without testing, so I'll mark this ready.

Just so that it is written down somewhere, when adding a new platform to contourpy I usually follow this process:

1. Wait for numpy nightly wheels to be built and uploaded.
2. Enable building, testing and wheel building in contourpy but with image testing disabled so that matplotlib isn't required.
3. Tell matplotlib that contourpy wheel are now available.
4. Wait for matplotlib nightly wheels to be built and uploaded.
5. Re-enable image testing in contourpy CI for the new platform.

There are contourpy wheels for win_arm64 available at https://pypi.anaconda.org/scientific-python-nightly-wheels/simple/contourpy/ for python 3.10 to 3.13. No 3.14 yet, I will deal with that soon-ish.

Yes, looks good now.

Failure is another set of the subprocess timeouts.