clang -O2  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations unistd/_PC_PRIO_IO.c -o unistd/_PC_PRIO_IO -D_POSIX_C_SOURCE=202405L  -lm  -lintl
unistd/_PC_PRIO_IO.c:2:17: error: use of undeclared identifier '_PC_PRIO_IO'
int const foo = _PC_PRIO_IO;
                ^
1 error generated.