0 < negative loop condition bug or misunderstanding on my part

[Timon Gehr]

On 03/07/2012 11:01 AM, Timon Gehr wrote:
> On 03/07/2012 07:05 AM, ixid wrote:
>> Ah, thank you, so it's wrapping. That seems like a bad idea, what is the
>> benefit to size being unsigned rather than signed? This case would seem
>> like one where allowing negatives is clearly better and more intuitive.
>
> The problem is not that length is unsigned. The issue is the implicit
> conversion from signed to unsigned. The right thing would be to disallow
> signed -> unsigned and unsigned -> signed implicit conversion unless
> value range propagation can prove it safe, and to make comparison
> between signed and unsigned actually work by translating it to more than
> one machine instruction.

Furthermore, bitwise boolean operators should still accept arguments of 
arbitrary signedness but the result should implicitly convert to both 
signed and unsigned.