It was added in commit 6be11e35d5397ae1c117eb840a969585fdd7d08d, "[libcxx] Implement c++2a char8_t input/output of std::filesystem::path".
It was added in commit 6be11e35d5397ae1c117eb840a969585fdd7d08d, "[libcxx] Implement c++2a char8_t input/output of std::filesystem::path".