Correct comparison of signed type with unsigned type (and vice versa)

[ponce]

On Thursday, 20 February 2014 at 22:52:55 UTC, Meta wrote:
> I can't think of any C code that would rely on such behaviour, 
> but I think it'd just be safer all-around to make it an error.

Eg this optimization:

     if ((unsigned int)(a - min) < (max - min)) // only one 
comparison instead of two
     {

     }

And there is many C codes relying on unsigned promotion, since 
signed overflow in C99 is undefined behaviour. The easiest way to 
force an operation is then to use one cast.