wctob
} else if (wc != L'\0' && (c = wctob(wc)) != EOF &&
extern int wctob(wint_t);
using std::wctob;
#define M_INVARIANT(c) (wctob(c) == EOF ? (c) : __m_invariant[c])
#define M_UNVARIANT(c) (wctob(c) == EOF ? (c) : __m_unvariant[c])