[libcxx-commits] [libcxx] [libc++] Provide flag for RUNTIMES_USE_LIBC=llvm-libc (PR #174967)

[Volodymyr Turanskyy via libcxx-commits]

voltur01 wrote:

I made this change consistent with other C library flags (picolibc and newlib), however I can imagine that the `defined(__LLVM_LIBC__)` checks did work because of some implicit definition of `__LLVM_LIBC__`, for example, via libc header files.

@petrhosek do you have more context in regards to existing checks for libc in libc++?

Alternative would be to define `__LLVM_LIBC__` in `__config_site` to keep existing checks, however this does not look good long term.

Thanks!

https://github.com/llvm/llvm-project/pull/174967