Error on negating unsigned types

[Johan Engelen via Digitalmars-d]

On Tuesday, 11 July 2017 at 19:57:06 UTC, Johan Engelen wrote:
> On Tuesday, 11 July 2017 at 19:46:00 UTC, Johan Engelen wrote:
>> The Weka folks would like to see a compile error on negating 
>> unsigned types:
>
> Also this nice hackery would need a workaround:
> ```
>    if ((y&(-y))==y)
> ```

http://www.exploringbinary.com/ten-ways-to-check-if-an-integer-is-a-power-of-two-in-c/

"The two’s complement of x is computed with ~x + 1, which inverts 
the bits of x and adds 1 (~x + 1 is equivalent to -x, but 
negation is technically illegal for an unsigned integer)."