dip1000 and preview in combine to cause extra safety errors

[Dukc]

On Wednesday, 8 June 2022 at 19:02:53 UTC, Steven Schveighoffer 
wrote:
> D already doesn't allow returning a pointer to stack data, even 
> in `@system` code. Doesn't this also qualify?
>
> -Steve

D does allow it, just not directly:

```D
// error
int* escape(int arg){return &arg;}

// ok
int* escape(int arg)
{ auto temp = &arg;
   return temp;
}
```

The philosophy is to force to be explicit in the simplest cases 
that are almost always errors, but not trying to seriously 
prevent the escape.