cc -O2 -pthread -I/usr/local/include  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations sys_socket/SO_PROTOCOL.c -o sys_socket/SO_PROTOCOL -D_POSIX_C_SOURCE=202405L  -lm -lpthread -lrt -L/usr/local/lib  -lintl -lcrypt
sys_socket/SO_PROTOCOL.c:2:17: error: 'SO_PROTOCOL' undeclared here (not in a function)
    2 | int const foo = SO_PROTOCOL;
      |                 ^~~~~~~~~~~