/opt/IBM/openxlC/17.1.1/bin/ibm-clang -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations sys_socket/SO_DOMAIN.c -o sys_socket/SO_DOMAIN -D_POSIX_C_SOURCE=202405L -lm -lpthread -lrt -latomic
sys_socket/SO_DOMAIN.c:2:17: error: use of undeclared identifier 'SO_DOMAIN'
int const foo = SO_DOMAIN;
                ^
1 error generated.