cc -pthread   -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations unistd/_POSIX_SYNCHRONIZED_IO.c -o unistd/_POSIX_SYNCHRONIZED_IO -D_POSIX_C_SOURCE=202405L -lm -lpthread -lrt -lintl -lcrypt -latomic
unistd/_POSIX_SYNCHRONIZED_IO.c:4:2: error: #error "_POSIX_SYNCHRONIZED_IO is not defined"
    4 | #error "_POSIX_SYNCHRONIZED_IO is not defined"
      |  ^~~~~