different scheme to check arguments to '%d', '%x', etc. Old scheme

did not work well when lua_Number is an integer.

lstrlib.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lstrlib.c,v 1.173 2011/11/30 18:24:56 roberto Exp roberto $
+** $Id: lstrlib.c,v 1.174 2012/04/03 19:06:19 roberto Exp roberto $
 ** Standard library for string operations and pattern-matching
 ** See Copyright Notice in lua.h
 */
@@ -758,9 +758,6 @@ static int str_gsub (lua_State *L) {
 #endif
 #endif				/* } */
 
-#define MAX_UINTFRM	((lua_Number)(~(unsigned LUA_INTFRM_T)0))
-#define MAX_INTFRM	((lua_Number)((~(unsigned LUA_INTFRM_T)0)/2))
-#define MIN_INTFRM	(-(lua_Number)((~(unsigned LUA_INTFRM_T)0)/2) - 1)
 
 /*
 ** LUA_FLTFRMLEN is the length modifier for float conversions in
@@ -872,18 +869,22 @@ static int str_format (lua_State *L) {
         }
         case 'd':  case 'i': {
           lua_Number n = luaL_checknumber(L, arg);
-          luaL_argcheck(L, (MIN_INTFRM - 1) < n && n < (MAX_INTFRM + 1), arg,
+          LUA_INTFRM_T ni = (LUA_INTFRM_T)n;
+          lua_Number diff = n - (lua_Number)ni;
+          luaL_argcheck(L, -1 < diff && diff < 1, arg,
                         "not a number in proper range");
           addlenmod(form, LUA_INTFRMLEN);
-          nb = sprintf(buff, form, (LUA_INTFRM_T)n);
+          nb = sprintf(buff, form, ni);
           break;
         }
         case 'o':  case 'u':  case 'x':  case 'X': {
           lua_Number n = luaL_checknumber(L, arg);
-          luaL_argcheck(L, 0 <= n && n < (MAX_UINTFRM + 1), arg,
+          unsigned LUA_INTFRM_T ni = (unsigned LUA_INTFRM_T)n;
+          lua_Number diff = n - (lua_Number)ni;
+          luaL_argcheck(L, -1 < diff && diff < 1, arg,
                         "not a non-negative number in proper range");
           addlenmod(form, LUA_INTFRMLEN);
-          nb = sprintf(buff, form, (unsigned LUA_INTFRM_T)n);
+          nb = sprintf(buff, form, ni);
           break;
         }
         case 'e':  case 'E': case 'f':