[libcxx-commits] [libcxx] [libc++] Properly guard std::filesystem with >= C++17 (PR #72701)

[Louis Dionne via libcxx-commits]

ldionne wrote:

I considered the risk of breakage here some more, and we're not removing the `std::__fs::filesystem` namespace (since that would be ABI-breaking). So most of these code examples would still work even after this patch, but not if they were trying to use filesystem in C++14. Given that mainline Clang is now using C++17 by default, I think this is unlikely to bite that many people.

https://github.com/llvm/llvm-project/pull/72701