I wondered if that’s why the proposal words it as “use C++ language facilities” instead of just “use C++” – use the C++ language, but not its stdlib.

I found this internal file that forms the basis of all the atoi and strol family functions. Seems like they do get some nice wins from the C++ language, without needing (e.g.) STL: https://github.com/llvm/llvm-project/blob/main/libc/src/__su...