clang -O2 -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations unistd/_POSIX2_CHAR_TERM.c -o unistd/_POSIX2_CHAR_TERM -D_POSIX_C_SOURCE=202405L -lm -lintl unistd/_POSIX2_CHAR_TERM.c:4:2: error: "_POSIX2_CHAR_TERM is not defined" #error "_POSIX2_CHAR_TERM is not defined" ^ 1 error generated.