In some instances, the regcomp() implementation would inadvertently s…

…ign-extend

a character in the regular expression.  Additionally, alphabetic wide-characters
were not properly being considered as such

Obtained from: FreeBSD

lib/libc/regex/regcomp.c

@@ -813,10 +813,10 @@ p_simp_re(struct parse *p, struct branchc *bc)
 	handled = false;
 
 	assert(MORE());		/* caller should have ensured this */
-	c = GETNEXT();
+	c = (uch)GETNEXT();
 	if (c == '\\') {
 		(void)REQUIRE(MORE(), REG_EESCAPE);
-		cc = GETNEXT();
+		cc = (uch)GETNEXT();
 		c = BACKSL | cc;
 #ifdef LIBREGEX
 		if (p->gnuext) {
@@ -977,7 +977,7 @@ p_count(struct parse *p)
 	int ndigits = 0;
 
 	while (MORE() && isdigit((uch)PEEK()) && count <= DUPMAX) {
-		count = count*10 + (GETNEXT() - '0');
+		count = count*10 + ((uch)GETNEXT() - '0');
 		ndigits++;
 	}
 
@@ -1287,7 +1287,7 @@ may_escape(struct parse *p, const wint_t ch)
 
 	if ((p->pflags & PFLAG_LEGACY_ESC) != 0)
 		return (true);
-	if (isalpha(ch) || ch == '\'' || ch == '`')
+	if (iswalpha(ch) || ch == '\'' || ch == '`')
 		return (false);
 	return (true);
 #ifdef NOTYET