* regex/regcomp.c (xwcrtomb): New function to convert wide chars

outside of the base plane to UTF-8.  Call throughout instead of
	wcrtomb.
	(wgetnext): Handle surrogate pairs on UTF-16 systems.
	* regex/regexec.c (xmbrtowc): Ditto.

winsup/cygwin/regex/regexec.c

@@ -84,8 +84,24 @@ xmbrtowc(wint_t *wi, const char *s, size_t n, mbstate_t *mbs, wint_t dummy)
 		if (wi != NULL)
 			*wi = dummy;
 		return (1);
-	} else
+	} else {
+		if (sizeof (wchar_t) == 2 && wc >= 0xd800 && wc <= 0xdbff) {
+			/* UTF-16 surrogate pair.  Fetch second half and
+			   compute UTF-32 value */
+			int n2 = mbrtowc(&wc, s + nr, n - nr, mbs);
+			if (n2 == 0 || n2 == (size_t)-1 || n2 == (size_t)-2) {
+				memset(mbs, 0, sizeof(*mbs));
+				if (wi != NULL)
+					*wi = dummy;
+				return (1);
+			}
+			if (wi != NULL)
+				*wi = (((*wi & 0x3ff) << 10) | (wc & 0x3ff))
+				      + 0x10000;
+			nr += n2;
+		  }
                 return (nr);
+	}
 }
 
 static __inline size_t