@matthiasdiener A few more issues I'd like to get your opinion on:

• spack install [email protected] %apple-clang@13: also fails on my macOS machine, with issues related to the old VERSION file interfering with other version files. Should we attempt to patch / fix / disable that as well?
• The same issue occurs with %clang@13:, where I have clang 13 installed from brew install llvm. However, I'm actually not quite sure if the Charm++ build picks up the correct compiler here, or if the system's apple-clang is used, because it is simply passed as ./build LIBS ARCH clang. The LLVM clang should be the one in PATH, but from the build output I don't immediately see if it's being used correctly.

@matthiasdiener A few more issues I'd like to get your opinion on:

• spack install [email protected] %apple-clang@13: also fails on my macOS machine, with issues related to the old VERSION file interfering with other version files. Should we attempt to patch / fix / disable that as well?

Not sure, are you interested in running 6.10.2 still? charmplusplus/charm#3112 is a pretty complicated patch :-(

• The same issue occurs with %clang@13:, where I have clang 13 installed from brew install llvm. However, I'm actually not quite sure if the Charm++ build picks up the correct compiler here, or if the system's apple-clang is used, because it is simply passed as ./build LIBS ARCH clang. The LLVM clang should be the one in PATH, but from the build output I don't immediately see if it's being used correctly.

Does this work correctly if not installing from spack?

@matthiasdiener For myself it wouldn't be worth the effort to fix versions below [email protected]. It would be good to avoid accidentally selecting broken versions though. Would it be too drastic to add conflict("platform=darwin", when="@:6.10.2 %apple-clang"), and the same for clang, which essentially disables all clang macOS builds below v7.0.0?

Let me know whether you want to add:

conflict("platform=darwin", when="@:6.10.2 %apple-clang")

or it is fine to merge this PR as is. Thanks!

@alalazo Please merge, I'll open separate PRs for the other issues once we make decisions on them.

@matthiasdiener For myself it wouldn't be worth the effort to fix versions below [email protected]. It would be good to avoid accidentally selecting broken versions though. Would it be too drastic to add conflict("platform=darwin", when="@:6.10.2 %apple-clang"), and the same for clang, which essentially disables all clang macOS builds below v7.0.0?

Imho, this might be too drastic. I think at least some older clang versions might not have the issue with the VERSION file, right?