A little puzzle

[Adam Burton]

Simen Kjaeraas wrote:

> On Mon, 19 Sep 2011 23:20:47 +0200, bearophile <bearophileHUGS at lycos.com>
> wrote:
> 
>> A tiny puzzle I've shown on IRC. This is supposed to create an inverted
>> array of cards, but what does it print instead?
>>
>> import std.stdio, std.algorithm, std.range;
>> void main() {
>>     int[52] cards;
>>     copy(iota(cards.length - 1, -1, -1), cards[]);
>>     writeln(cards);
>> }
> 
> Gawds, that's an ugly bug. For those who can't spot it,
> typeof(cards.length) == uint, hence -1 is converted to a uint
> (4_294_967_295, to be exact). iota then says 'that's fine, I'll just
> return an empty range for you.'
> Solution: knock some sense into integral promotion rules.
> Workaround: cast(int)cards.length.
> 
> What was the rationale for having unsigned array lengths, again?
> 
That's not what happened for me. It failed to compile for me due to 
ElementType of Range1 not matching Range2 ElementType. Could this be due to 
using 64bit (size_t is ulong)?