Project Elvis

[Jonathan M Davis]

On Sunday, October 29, 2017 17:35:25 Nemanja Boric via Digitalmars-d wrote:
> On Sunday, 29 October 2017 at 17:19:44 UTC, Jonathan M Davis
>
> wrote:
> > On Sunday, October 29, 2017 16:44:39 Ola Fosheim Grøstad via
> >
> > Digitalmars-d wrote:
> >> On Sunday, 29 October 2017 at 16:29:57 UTC, Jonathan M Davis
> >>
> >> wrote:
> >> > valid using ?:, I would think that you'd want to be doing
> >> > the same check with stuff like if statements anyway. So, it
> >> > sounds to me like overloading opCast!bool would work just
> >> > fine.
> >>
> >> If you try to do:
> >>
> >> some_float ?: 0.0
> >>
> >> then it will do nothing as cast(bool)std.math.NaN(0) => true
> >
> > NaN is supposed to always be false.
>
> OT, but I had to :-)
>
> ```
> void main()
> {
>   import std.stdio;
>
>   float x;
>   x? writeln("Oh no, a NaN!") : writeln("All good.");
> }
> ```
>
> Same happens for assert(float.nan) - it doesn't fail.

Sounds like a bug to me. NaN is supposed to be false whenever it's used in a
comparison. If it it's true when cast directly to bool, then that's
inconsistent.

- Jonathan M Davis