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