mbtowc
mbtowc(&wc, NULL, 1); /* state init */
if ((flags & VUNSET) || mbtowc(&wc, lit_ch, strlen(lit_ch)) <= 0)
int mbtowc(wchar_t * __restrict, const char * __restrict, size_t);
psenc = &_CEI_TO_STATE(_TO_CEI(cl), mbtowc);
ret = mbtowc(NULL, NULL, 0);
ret = mbtowc(NULL, illegal, strlen(illegal));
mbtowc(NULL, NULL, 0);
ret = mbtowc(NULL, legal, strlen(legal));
ret = mbtowc(&wc, "\xe4", 1);
(void)mbtowc(NULL, NULL, 0);
n = mbtowc(&wch, p + all, (len = strlen(p + all)) + 1);
(void)mbtowc(NULL, NULL, 0);
if (mbtowc(&wc, wbuf, nmax) < 0)