[clang] [libcxx] [Clang] Add __builtin_common_reference (PR #121199)

[Nikolas Klauser via cfe-commits]

philnik777 wrote:

> This seems reasonable to me? I'm not a huge fan of how much is being put into `SemaTemplate.cpp` to support all the builtins though. I'm wondering if we need to split that up in a follow-up and have a `SemaTemplateBuiltins` for all of these to live.

I can take a look at splitting things up in a follow-up. Shouldn't be too complicated. I do wonder whether it's worth the split, since it's a relatively small amount of code. OTOH it's a very clean split...

> Please let Aaron/others take a poke at this, and make sure there are a few more Libc++ reviewers to make sure you're all in agreement with how this works (I see the convo that is happening).
> 
> Also, should we loop in libstdc++ folks here?

IDK whether they have any thought on this, but certainly doesn't hurt. CC @jwakely


https://github.com/llvm/llvm-project/pull/121199