avoid warning about -unsigned value

lstrlib.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lstrlib.c,v 1.167 2011/05/03 16:01:57 roberto Exp roberto $
+** $Id: lstrlib.c,v 1.168 2011/06/09 18:22:47 roberto Exp roberto $
 ** Standard library for string operations and pattern-matching
 ** See Copyright Notice in lua.h
 */
@@ -45,7 +45,7 @@ static int str_len (lua_State *L) {
 /* translate a relative string position: negative means back from end */
 static size_t posrelat (ptrdiff_t pos, size_t len) {
   if (pos >= 0) return (size_t)pos;
-  else if (-(size_t)pos > len) return 0;
+  else if (0u - (size_t)pos > len) return 0;
   else return len - ((size_t)-pos) + 1;
 }
 

ltable.c

@@ -1,5 +1,5 @@
 /*
-** $Id: ltable.c,v 2.58 2011/06/02 19:31:40 roberto Exp roberto $
+** $Id: ltable.c,v 2.59 2011/06/09 18:23:27 roberto Exp roberto $
 ** Lua tables (hash)
 ** See Copyright Notice in lua.h
 */
@@ -88,7 +88,7 @@ static Node *hashnum (const Table *t, lua_Number n) {
   int i;
   luai_hashnum(i, n);
   if (i < 0) {
-    if ((unsigned int)i == -(unsigned int)i)
+    if (cast(unsigned int, i) == 0u - i)  /* use unsigned to avoid overflows */
       i = 0;  /* handle INT_MIN */
     i = -i;  /* must be a positive value */
   }