[libcxx-commits] [libcxx] [libc++] Allow the use of extensions in the implementation (PR #79532)

[Sam McCall via libcxx-commits]

sam-mccall wrote:

Thanks! If we can avoid this entirely that seems ideal for everyone.

We only see the regression in our modular builds. (Which unfortunately is our main mode).
We use clang header modules, but I'd guess this isn't specific to that mode.
libc++ has modules buildbots right? I'll see if I can scrape some timings out of those, 50% might be possible to see through noise.

https://github.com/llvm/llvm-project/pull/79532