cc -O2 -pipe  -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations fcntl/F_OWNER_PGRP.c -o fcntl/F_OWNER_PGRP -D_POSIX_C_SOURCE=202405L  -lm -lpthread 
fcntl/F_OWNER_PGRP.c:2:17: error: use of undeclared identifier 'F_OWNER_PGRP'
int const foo = F_OWNER_PGRP;
                ^
1 error generated.