+ int res;
+
+#ifdef WIN32
+ /* Writing to the console is a lot of fun on Microsoft Windows.
+ * If you use the standard I/O functions, you must use the OEM code page,
+ * which is different from the usual ANSI code page. Or maybe not, if the
+ * user called "chcp". Anyway, we prefer Unicode. */
+ int fd = _fileno (stream);
+ if (likely(fd != -1) && _isatty (fd))
+ {
+ res = vasprintf (&str, fmt, ap);
+ if (unlikely(res == -1))
+ return -1;
+
+ size_t wlen = 2 * (res + 1);
+ wchar_t *wide = malloc (wlen);
+ if (likely(wide != NULL))
+ {
+ wlen = MultiByteToWideChar (CP_UTF8, 0, str, res + 1, wide, wlen);
+ if (wlen > 0)
+ {
+ HANDLE h = (HANDLE)(intptr_t)_get_osfhandle (fd);
+ DWORD out;
+
+ WriteConsoleW (h, wide, wlen - 1, &out, NULL);
+ }
+ else
+ res = -1;
+ free (wide);
+ }
+ else
+ res = -1;
+ free (str);
+ return res;
+ }
+#endif
+
+ res = utf8_vasprintf (&str, fmt, ap);
+ if (unlikely(res == -1))