cc -pthread   -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations sys_mman/O_RDONLY.c -o sys_mman/O_RDONLY -D_POSIX_C_SOURCE=202405L -lm -lpthread -lrt  -lgdbm_compat -lcrypt -latomic
sys_mman/O_RDONLY.c:3:17: error: ‘O_RDONLY’ undeclared here (not in a function)
    3 | int const foo = O_RDONLY;
      |                 ^~~~~~~~