A little puzzle

[Timon Gehr]

On 09/20/2011 12:50 AM, Adam Burton wrote:
> 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)?

If you recompile with the -m32 switch it should be accepted.