Cross compiling for macOS ARM64 producing x86 libraries (cmake involved)

[epeisach]

export CIBW_ARCHS_MACOS="x86_64 arm64" cibuildwheel --config cibuildwheel.toml --output-dir "$(System.DefaultWorkingDirectory)/dist" .
cibuildwheel.toml:
[[tool.cibuildwheel.overrides]] select = "*-musllinux*" before-all = "apk add flex bison cmake"

So setup.py is invoking cmake. The built libraries for macOS are MachO - x86_64 in both case.

I suspect that I will need to pass a flag to cmake to enable cross compiling.
a) Is there an environment variable set indicating building architecture - so I can detect in setup.py
b) Any ideas what I would pass to CMAKE?

[henryiii]

I would recommend using scikit-build-core or other dedicated backend. If you want to do it yourself, see https://github.com/pybind/cmake_example/blob/cbcf742c566a8bfd1f079b3d87778b17fef4bef5/setup.py#L103/

[epeisach]

Thank you ---- this is a pybind scenario. I suppose I can set an environment variable for cibuildwheel - so only attach architecture if cibuildwheel. That way distinguish cibuildwheel from someone building naively.

[henryiii]

No, you want to solve this for all possible builders, like the conda family too. You should read ARCHFLAGS and convert it to CMAKE_OSX_ARCHITECTURES, like I showed in the example above.

Though I'd highly recommend a dedicated builder over handling every possible situation yourself. More things will arise that scikit-build-core has already solved.

[epeisach]

Do to requirement for python 2 support - at the moment, I went with the example - and it works for now. I have another project that I will retrofit to use scikit-build-core.