cc -pipe -O   -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations fcntl/struct-f_owner_ex.c -o fcntl/struct-f_owner_ex -D_POSIX_C_SOURCE=202405L  -lm -lpthread -lrt  -lrt -lcrypt
fcntl/struct-f_owner_ex.c:2:19: error: storage size of 'foo' isn't known
 struct f_owner_ex foo;
                   ^~~