Signed integer overflow undefined behavior or not?

[John Colvin via Digitalmars-d]

On Friday, 13 November 2015 at 10:20:53 UTC, Don wrote:
> On Friday, 13 November 2015 at 09:37:41 UTC, deadalnix wrote:
>> On Friday, 13 November 2015 at 09:33:51 UTC, John Colvin wrote:
>>> I don't understand what you think is so complicated about it?
>
>>> After arithmetic operations f is applied
>>> signed: f(v) = ((v + 2^(n-1)) mod (2^n - 1)) - 2^(n-1)
>
> Complicated in the sense that: when are those semantics useful? 
> The answer of course, is, pretty much never. They are very 
> bizarre.

They are 99% useless, I agree. The only good argument for them I 
can think of is that it's a faithful mapping to the underlying 
machine.