cc -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations wchar/getwchar.c -o wchar/getwchar -D_POSIX_C_SOURCE=202405L -lm -lpthread -lrt -lintl -liconv
wchar/getwchar.c:5:23: error: ‘getwchar’ undeclared here (not in a function)
    5 | wint_t (*foo)(void) = getwchar;
      |                       ^~~~~~~~