x86_64-linux-mlibc-gcc -O2 -march=x86-64 -pipe -mtune=generic -pthread   -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations unistd/_PC_ASYNC_IO.c -o unistd/_PC_ASYNC_IO -D_POSIX_C_SOURCE=202405L -lm -lpthread -lrt -lcrypt -lintl -liconv
unistd/_PC_ASYNC_IO.c:2:17: error: ‘_PC_ASYNC_IO’ undeclared here (not in a function)
    2 | int const foo = _PC_ASYNC_IO;
      |                 ^~~~~~~~~~~~