Range Redesign: Empty Ranges

[Atila Neves]

On Monday, 4 March 2024 at 21:29:40 UTC, Jonathan M Davis wrote:
> Okay. A few weeks ago, I made a post about potential design 
> decisions when updating the range API in the next version of 
> Phobos, and this is a continuation of that, albeit with a 
> different set of problems. Specifically:
>
> [...]

I like T.init being empty. I thought I'd found a clever way to 
make this work for classes but apparently this crashes, much to 
my surprise:

```d
class Class {
     bool empty() @safe @nogc pure nothrow scope const {
         return this is null;
     }
}

Class c;
assert(c.empty);
```

This, although supposedly equivalent, works fine:

```d
class Class {}
bool empty(in Class c) @safe @nogc pure nothow {
     return c is null;
}
```

Which might be a way out? I still think the first example should 
work.