cc -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations fcntl/struct-f_owner_ex-pid.c -o fcntl/struct-f_owner_ex-pid -D_POSIX_C_SOURCE=202405L  -lm -lpthread  -liconv
fcntl/struct-f_owner_ex-pid.c:2:17: error: declaration of 'struct f_owner_ex' will not be visible outside of this function [-Werror,-Wvisibility]
    2 | void foo(struct f_owner_ex* bar)
      |                 ^
fcntl/struct-f_owner_ex-pid.c:4:19: error: incomplete definition of type 'struct f_owner_ex'
    4 |         pid_t *qux = &bar->pid;
      |                       ~~~^
fcntl/struct-f_owner_ex-pid.c:2:17: note: forward declaration of 'struct f_owner_ex'
    2 | void foo(struct f_owner_ex* bar)
      |                 ^
2 errors generated.