How to cross-compile dylib on macos?

[louisabraham]

Description

On https://github.com/louisabraham/pydivsufsort/, my setup.py calls a bash file that builds a dylib file.

https://github.com/louisabraham/pydivsufsort/blob/33802969cbe1bcc3a29ea5c10bc281205794c3e4/setup.py#L39-L52

class build(_build):
    def run(self):
        if platform.system() == "Windows":
            witness = Path(__file__).parent / "pydivsufsort/divsufsort.dll"
            assert witness.exists(), "Launch ./build.sh first"
        elif platform.system() == "Darwin":
            script = Path(__file__).parent / "build.sh"
            path = script.absolute().as_posix()
            Popen(["arch", "-" + platform.machine(), path], shell=False).wait()
        else:
            script = Path(__file__).parent / "build.sh"
            path = script.absolute().as_posix()
            Popen([path], shell=True, executable="/bin/bash").wait()
        super().run()

Calling arch works only if platform.machine() returns the correct value. However I think that cibuildwheel uses a x86_64 interpreter even for cross-compilation builds.

Is there a way for me to detect from setup.py that cibuildwheel is trying to cross-compile?

Build log

No response

CI config

https://github.com/louisabraham/pydivsufsort/blob/33802969cbe1bcc3a29ea5c10bc281205794c3e4/.github/workflows/build-and-upload.yml

[louisabraham]

Related issue: #1537

It's weird because I'm already using platform.machine().

[joerick]

sysconfig.get_platform() will pick up the cross-compilation flags that cibuildwheel sets. Have you tried that?

[louisabraham]

The problem is that I get machine macosx-10.9-universal2. Can I get either arm64 or x86_64 ?

[joerick]

If you're running cibuildwheel with CIBW_ARCHS_MACOS=x86_64 arm64, then you won't get universal2. If you're running setup.py outside of cibuildwheel, then I guess it matches the arch that the interpreter was built with, which is universal2.