Decide about osx-arm64; fix it if supported

[h-vetinari]

If osx-arm64 is a supported platform (and going forward, that basically asks whether osx is a supported platform, as arm architecture takes over), then the builds should be green.

There have been many merges here with broken CI for osx-arm64, which leads to resolution errors downstream (e.g. conda-forge/stir-feedstock#116).

IMO osx-arm64 needs to be either fixed (preferable) or dropped.

[h-vetinari]

CC @chrisburr @vepadulano

[henryiii]

IIRC the original problem is ROOT can't be cross-compiled, so @chrisburr was manually building ARM packages locally. I would assume we might have native support in conda-forge's CI now?

[h-vetinari]

Thanks for the context. Should we re-attempt cross-compilation? I don't remember many cases where that wasn't ultimately solvable (even if we need to compile some extra stuff for the build agent architecture during building).

I would assume we might have native support in conda-forge's CI now?

No we don't yet. The macos-14 images are still running on amd64 agents at last check

[matthewfeickert]

IIRC the original problem is ROOT can't be cross-compiled, so @chrisburr was manually building ARM packages locally

Is there someplace where there's a summary of the issues on why ROOT can't be cross-compiled?

@chrisburr, were you doing something beyond just running python build-locally.py? If not, then some of us who have Apple silicon machines could help out with this.

[aphecetche]

Can someone (yep, that might include myself, if instructed properly 😉 ) with an Apple Silicon be of any help to try to solve this or is there a fundamental technical problem preventing it ? (I have no idea how conda builds work, sorry, I'm just an end user currently)

(I'd love to be able to work again with a Conda Root package on my M1 Mac...)

[chrisburr]

I finally got true cross-compilation working in #280. It's not pretty but I'll try to clean it up and upstream patches/report bugs as part of updating to 6.34.