Builds for me on an M1 mac, but this probably shouldn't be preferred since it's a pre-release version.

Will defer merge decision to give maintainers a chance to comment.

@William-Mou, I'm good with adding this verison, but as it is it would become the default version of llvm built for spack install llvm, would you add preferred=True to the last stable version below this so we can avoid that?

Hi @trws, Thank you for your reminder!
I've added this flag to the last stable version.

Can we remove the rc version from Spack after LLVM 15 is released? Or will it stay around forever?

Notice that spack install [email protected] is possible too without this PR with the only downside that you don't get shasum verification on the sources.

Hi @haampie,
I'm not sure if this is the question posed to me, but it seems to me that we should remove this version when llvm 15.0.0 is released.
In my view, 15.0.0-rc1 appears as an option in spack, which can enhance the confidence of users.

Hi,
It has been a while since I responded.
Should I close this PR?

Looks like CI pipeline has hung.

@spackbot run pipeline

I've started that pipeline for you!