Movement against float.init being nan

[Basile B.]

On Friday, 19 August 2022 at 13:42:58 UTC, Hipreme wrote:
> As someone coming from Java to use D, I find it myself quite 
> annoying that float and double are initialized to `nan`.
>
> This is really bad, it is hard to detect for newcomers, there 
> is no flag by default to throw an exception when some operation 
> on nan is done. It can be misleading if you're not paying a lot 
> of attention to what you're doing.
>
> What I suggest is what any sane people would: use 0 as the 
> start for float and double. 0 is the most common sense as a 
> starting point for everything, and, there are 2 options we 
> could go:
>
>
> 1: Emit a compilation error that every variable must be 
> initialized (I thought D were trying to avoid runtime errors)
> 2: 0 init all types, so, none is actually invalid before use
>
>
> Even `char` took me as surprise to know it actually starts as 
> 0xff, I lost a bit of time trying to find that bug because it 
> is so common that variables init as zero.
>
> Although the `char` is a bit different beast in terms of 
> breaking change, I really *can't see* anyone actually depending 
> that your float is being initialized with `nan`, so I really 
> would like to know how much people agree with this idea. It is 
> so common to stumble on that problem that it is starting to 
> feel as a real mistake.

It's not a mistake, default initialization in D is not designed 
to be an initialization substitute, it's designed in a way that 
missing initialization is easily detectable but not UB. However, 
thruth is that this only works for character and floating point 
types.

Changing that design would require a DIP I think.