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