Homebrew on macOS

[simonjwright]

I've been working on integrating Homebrew into Alire.

I've got it to a point where it works for me; I patched up the ci-linux and ci-macos workflows, the only reasons the latter failed were

-Ada -> Alire_Host_Distro: distro_unknown
+Ada -> Alire_Host_Distro: macos

and

-C -> Alire_Host_Distro: distro_unknown
+C -> Alire_Host_Distro: macos

Is this work of interest? If so, what branch should I base a PR on? (I would do a merge squash on the relevant commits I've made so far in my homebrew-dev branch.)

Further,

• Is macos OK for Alire.Platforms.Distribution? (actually MacOS). Obviously the test that failed above needs fixing!
  • That would be adding e.g. on_macos() to testsuite/drivers/helpers.py, and altering distribution() to use it. I see that platform.system() returns Darwin, I guess using darwin instead of macos would confuse people!
• Is there a way of running github actions for testing crates using this version of alr from my repo?
• What would the process be for amending external manifests, e.g. sdl2, sdl2_ttf, sdl2_image? We could invite Mac users to make/propose changes as needed?
• What would the process be for amending crates that could use this ability, e.g. sdlada (which is maintained by @mosteo but authored by Luke Guest), and ought to use $HOMEBREW_PREFIX to find include & library files (Homebrew don't recommend moving it from its default location, but the default location is different between x86_64 and aarch64!)

[Fabien-Chouteau]

Thanks a lot @simonjwright !

I commented on PR for code details.

• Is macos OK for Alire.Platforms.Distribution? (actually MacOS). Obviously the test that failed above needs fixing!

As I said on the PR, the distribution should be Homebrew.

* Is there a way of running github actions for testing crates using this version of `alr` from my repo?

I am not sure, we have the Crate CI stuff but I don't know if you can use it (@mosteo ).

* What would the process be for amending external manifests, e.g. `sdl2`, `sdl2_ttf`, `sdl2_image`? We could invite Mac users to make/propose changes as needed?

Once we have this merged in Alire, we can have an extra CI platform that is macOS + Homebew and then you will be able to op PR on the community index to add Homebew packages to the externals.

* What would the process be for amending crates that could use this ability, e.g. `sdlada` (which is maintained by @mosteo but authored by Luke Guest), and ought to use `$HOMEBREW_PREFIX` to find include & library files (Homebrew don't recommend moving it from its default location, but the default location is different between x86_64 and aarch64!)

If it's a change to the code then you have to see with the authors. If it's a change to the manifest then we can review it.