(unsigned) means (unsigned int) which on ptrdiff_t or size_t or other

larger types really is a range reduction...
Almost any cast to (unsigned) is a bug.
ok millert tb benno

src/usr.sbin/ntpd/parse.y

@@ -1,4 +1,4 @@
-/*	$OpenBSD: parse.y,v 1.70 2018/11/01 00:18:44 sashan Exp $ */
+/*	$OpenBSD: parse.y,v 1.71 2019/02/13 22:57:08 deraadt Exp $ */
 
 /*
  * Copyright (c) 2002, 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -668,7 +668,7 @@ yylex(void)
 	if (c == '-' || isdigit(c)) {
 		do {
 			*p++ = c;
-			if ((unsigned)(p-buf) >= sizeof(buf)) {
+			if ((size_t)(p-buf) >= sizeof(buf)) {
 				yyerror("string too long");
 				return (findeol());
 			}
@@ -707,7 +707,7 @@ nodigits:
 	if (isalnum(c) || c == ':' || c == '_' || c == '*') {
 		do {
 			*p++ = c;
-			if ((unsigned)(p-buf) >= sizeof(buf)) {
+			if ((size_t)(p-buf) >= sizeof(buf)) {
 				yyerror("string too long");
 				return (findeol());
 			}