disabling unary "-" for unsigned types

[Steven Schveighoffer]

On Tue, 16 Feb 2010 10:36:04 -0500, Daniel Keep  
<daniel.keep.lists at gmail.com> wrote:

>
> It's fun to note that one of the fixes the author proposes in the
> article was actually shown to itself be wrong... nearly two years later.
>
> Clearly, knowing that computers use two's complement fixed-width integer
> arithmetic is insufficient to write correct code.  To believe otherwise
> is to believe that humans are infallible.

Yes, but in this case, the solution was incorrect for a small number of  
inputs (arrays with length > 2^30).

For negation of unsigned values, the code is incorrect for all inputs  
except for zero.

Appropriately, one will notice something is wrong sooner than a decade.  I  
would postulate they should know instantaneously because the compiler  
should reject it :)

-Steve