+#if defined(_POSIX_SOURCE) || defined(_POSIX_C_SOURCE) \
+ || defined(_XOPEN_SOURCE) || defined(_GNU_SOURCE)
+size_t mbsnrtowcs(wchar_t *, const char **, size_t, size_t, mbstate_t *);
+size_t wcsnrtombs(char *, const wchar_t **, size_t, size_t, mbstate_t *);
+#endif
+
+#if defined(_XOPEN_SOURCE) || defined(_GNU_SOURCE)
+int wcwidth (wchar_t);
+int wcswidth (const wchar_t *, size_t);