Re: bug in table.sort (lua 5.1.3)

[Roberto Ierusalimschy <roberto@...>]

> The fix:
> 
> [...]
> -        if (i>u) luaL_error(L, "invalid order function for sorting");
> +        if (i>=u) luaL_error(L, "invalid order function for sorting");
>          lua_pop(L, 1);  /* remove a[i] */
> [...]
> -        if (j<l) luaL_error(L, "invalid order function for sorting");
> +        if (j<=l) luaL_error(L, "invalid order function for sorting");

The first change is ok, but I am not sure about the second. The first
part of the code arranges for a[l] and a[u] to act as sentinels. Because
the pivot goes to a[u-1], it works as a sentinel too. So, i should never
go up to u. But in the lower end the sentinel is still a[l]. So, when
there are no elements left that are smaller than the pivot, it is ok
for j to go down up to l (the sentinel). Of course, this stops the loop
(because j<i), but it does not mean an error in the order function.

-- Roberto