cc -O2 -pipe  -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations fcntl/struct-f_owner_ex-type.c -o fcntl/struct-f_owner_ex-type -D_POSIX_C_SOURCE=202405L  -lm -lpthread 
fcntl/struct-f_owner_ex-type.c:2:17: error: declaration of 'struct f_owner_ex' will not be visible outside of this function [-Werror,-Wvisibility]
void foo(struct f_owner_ex* bar)
                ^
fcntl/struct-f_owner_ex-type.c:4:17: error: incomplete definition of type 'struct f_owner_ex'
        int *qux = &bar->type;
                    ~~~^
fcntl/struct-f_owner_ex-type.c:2:17: note: forward declaration of 'struct f_owner_ex'
void foo(struct f_owner_ex* bar)
                ^
2 errors generated.