-0 assigned to a FP variable

[Olivier Pisano]

Le 10/01/2011 01:27, bearophile a écrit :
> A bug I've introduced once in my D code, are you able to spot it?
>
> void main() {
>      double x = +0;
>      double y = -0;
> }
>
>
> The bug: 'y' isn't the desired double -0.0
>
> To avoid this bug DMD may keep the -0 and +0 integer literals represented in two distinct ways, so they have two different values when/if assigned to a floating point. (But here D will behave a little differently from C).
> An alternative is to just add a warning to DMD.
> A third possibility is to just ignore this probably uncommon bug :-)
>
> Bye,
> bearophile

Hi,

Do you suggest the compiler should guess you want -0.0 and convert 0 to 
double before applying the unary minus operator ?

I suppose such a fix would be likely to create many more bugs than the 
one it is suppose to solve.

I don't have a clue on what kind of user code needs to differentiate 0.0 
and -0.0 fp litterals, but I humbly suppose that it must be kind of rare.