Integer overflow and underflow semantics

[Paul D. Anderson]

On Sunday, 6 May 2012 at 16:27:34 UTC, Alex Rønne Petersen wrote:
> On 05-05-2012 06:57, Alex Rønne Petersen wrote:
>> Hi,
>>
>> I don't think the language really makes it clear whether 
>> overflows and
>> underflows are well-defined. Do we guarantee that for any 
>> integral type
>> T, T.max + 1 == T.min and T.min - 1 == T.max?
>>
>> This is relevant in particular for GDC and LDC since they 
>> target a lot
>> of weird architectures.
>>
>
> Can anyone give a definitive answer to this or at least confirm 
> that it is an open issue?

I don't have the reference at the moment but the C99(?) standard 
requires wraparound behavior by UNSIGNED integer values. I don't 
know if there is an equivalent requirement for signed values.