[llvm-branch-commits] [libcxx] release/18.x: [libc++] Enable availability based on the compiler instead of __has_extension (#84065) (PR #84374)

[Louis Dionne via llvm-branch-commits]

ldionne wrote:

No, it's not legitimate. Our CI is rather unstable at the moment but this looks as good as it'll get.

https://github.com/llvm/llvm-project/pull/84374