x86_64-managarm-gcc -pthread   -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations unistd/_XOPEN_SHM.c -o unistd/_XOPEN_SHM -D_POSIX_C_SOURCE=202405L -lm -lpthread -lrt  -lintl -liconv -lintl -liconv
unistd/_XOPEN_SHM.c:9:2: error: #error "_XOPEN_SHM is not defined"
    9 | #error "_XOPEN_SHM is not defined"
      |  ^~~~~