Discussion Thread: DIP 1039--Static Arrays with Inferred Length--Community Review Round 1

[Luhrel]

On Thursday, 7 January 2021 at 15:27:09 UTC, Dukc wrote:
> On Thursday, 7 January 2021 at 13:03:54 UTC, Luhrel wrote:
>> 2. if staticArrFunc returns a size_t, then the problem can be 
>> simplified as:
>> ```
>> staticArrFunc(cast(int[$])[1,2,3]); // no need to cast :
>> staticArrFunc([1,2,3]); // already works like that (if 
>> staticArrFunc takes a int[3])
>> ```
>
> If your DIP is implemented, what you say is true. But the point 
> is that right now it means a different thing - a cast to static 
> array of the length of `something` (in the full example), not 
> to length of `[1,2,3]`. The point is that your DIP will 
> silently change the behaviour of code like this.

I understand want do you mean, but we're currently unable to use 
the `$` operation from `something` inside a cast.

```
int staticArrFunc(int[6] a)
{
     return a[0];
}

void main()
{
     int[] s = [1, 2, 3, 4, 5, 6];
     int[] y = s[0 .. staticArrFunc(cast(int[$]) [1,2,3])];
     // Error: CTFE internal error: trying to access uninitialized 
var
}
```

Do you have a currently working example, that would potentially 
be broken by my DIP ?

>
> I do agree that this is such a rare enough occurence that we 
> might be best off just accepting it. But it needs to be 
> mentioned in the DIP.

I don't want a DIP that will break other people codes.