clang -O2  -Wall -Wextra -Werror=implicit-function-declaration spawn/posix_spawn_file_actions_addfchdir.c -o spawn/posix_spawn_file_actions_addfchdir -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm  -lintl
spawn/posix_spawn_file_actions_addfchdir.c:44:16: error: implicit declaration of function 'posix_spawn_file_actions_addfchdir' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
        if ( (errno = posix_spawn_file_actions_addfchdir(&actions, dirfd)) )
                      ^
spawn/posix_spawn_file_actions_addfchdir.c:44:16: note: did you mean 'posix_spawn_file_actions_addclose'?
/usr/include/spawn.h:57:5: note: 'posix_spawn_file_actions_addclose' declared here
int posix_spawn_file_actions_addclose(posix_spawn_file_actions_t *, int);
    ^
1 error generated.