clang -O2  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations dirent/dirfd.c -o dirent/dirfd -D_POSIX_C_SOURCE=202405L  -lm  -lintl
dirent/dirfd.c:5:21: error: use of undeclared identifier 'dirfd'
int (*foo)(DIR *) = dirfd;
                    ^
1 error generated.