Apple Silicon Foreign Library Support (#8227)

[yobson]

Fix for issue #8227 and #7837

• Allowed building Foreign Libraries for all architecture on apple
  silicon
• Updated error message to name Mac OS instead of OSX as supported
  platform

---

Please include the following checklist in your PR:

• Patches conform to the coding conventions.
• Any changes that could be relevant to users have been recorded in the changelog.
• The documentation has been updated, if necessary.

I successfully compiled a dylib, although I confess that I have't tested said dylib.

[Mikolaj]

LGTM.

Would it be possible to have a tiny test so that we know for a fact it's fixed next time the code around this feature changes (or fails to change)?

The change is in package Cabal, so I think that's what should be in packages: in the changelog.

[yobson]

Not a problem! I've not looked at Cabal's testing system before, any pointers?

[Mikolaj]

git grep OSX turns out a test with some of the same keywords: cabal-testsuite/PackageTests/ForeignLibs/setup.test.hs

This kind of testing is described at https://github.com/haskell/cabal/tree/master/cabal-testsuite

[Mikolaj]

BTW, does our CI run Apple Silicon? could it? @jneira, @andreabedini?

[yobson]

I'm running the tests now; the file you referenced doesn't look like it needs any cases added, it just needs to be run on an apple silicon Mac. If not, I'm not certain how is best to ensure it runs on A64 without an A64 Mac builder.

I'm running the tests now to see if they pass on my Mac

[Mikolaj]

We could try somehow faking it, so that cabal thinks it's Apple Silicon. In any case, if the test tests what it should and if all tests pass for you, that's a good foundation, whether we extend CI or not.

[yobson]

ForeignLibs $ cabal run cabal-tests
Up to date
threads: 1
tests to run: 1
setup.test.hs  OK (9.01s)
SKIPPED 0 tests
OK

Looks like it passed! This test builds a foreign library, links it to a c program and runs that c program. Pretty comprehensive.

[Mikolaj]

That's probably the best we can do.

[andreabedini]

@Mikolaj AFAIK GitHub Actions doesn't support Apple Silicone yet (see roadmap issue). The GitHub Actions runner does so if someone has spare apple m1 machines one could self-host it.

[yobson]

https://www.macstadium.com/opensource

They say that they offer free macs (remote) to open source projects. I wonder if the haskell project as a whole could approach them? Or maybe they have? I think it would be easier to get a machine for ghc, cabal etc, that it would for just cabal.

Anyway, if no one has approached them, I'd be happy to

[Kleidukos]

Can't we mutualise CI resources with the GHC project?
cc @chreekat

[chreekat]

@Kleidukos GHC does have some mac runners for gitlab.haskell.org! I'm not aware of any runners for github, unfortunately.

Creating (shared?) resources for other projects besides GHC is on the backlog for the Haskell Foundation. You could already talk to @david-christiansen about just getting some devices sponsored...

[angerman]

All this change does is remove an architecture filter. I have some serious doubt that this PR does need a validation on aarch64-darwin in CI to be acceptable. Let's just merge it. This PR is perfectly fine.

On the general CI topic. GHC does have 6 M1 macs. 3 sponsored by simspace, 3 sponsored by me. We used to have one or two from macstadium, and I'm not sure if @bgamari is still renting some there?

As with many providers getting someone to actually offer you performant and recent mac hardware is fairy tricky. (or get's expensive fast); if cabal was hosted on gitlab.haskell.org, it would get access to all the GHC builders. There are even two windows runners I also sponsor. Moving stuff to gitlab is clearly not an easy option. At the same time providing non containerised ressources to github opens up all kinds of other concerns (gitlab effectively only offers security through obscurity here).

[Mikolaj]

We do want to test even silly things, but not at the cost of maintaining CI on github and gitlab, so let's wait with the testing until we can extend our single CI script to Apple Silicon easily. @yobson: anything to add or do we merge now (via merge_me label)?

[yobson]

I'm happy to merge!

[Mikolaj]

@Mergifyio backport 3.8

[mergify]

backport 3.8

✅ Backports have been created

• #8243 Apple Silicon Foreign Library Support (#8227) (backport #8232) has been created for branch 3.8