Possible bug when instantiating template function with nested struct

[Alexandru Ermicioi]

On Sunday, 7 November 2021 at 14:08:32 UTC, Basile B. wrote:
>
> - `.length` and `.ptr` becomes functions calls.
> - things like `.length++` is not really supported, you have to 
> make a `Length` struct for that

That would make sense, since even right now .length is not just a 
simple number, otherwise, you wouldn't be able change the size of 
an array (i.e. allocate more memory).

> - implicit conversions, templates constraints, would lead to 
> plenty of templates instances (things like `if (is(T == U[]))` 
> would require to instantiate `U[]` right ?)

No idea about it being instantiated in is template. Are templates 
instantiated when doing is expression checks? Question to people 
knowledgeable about this.

> - dynamic arrays are part of the type system, being `TypeNext` 
> derived they share common methods with pointers and static 
> arrays.

That would be a breaking change, if the struct is not treated 
specially by compiler (i.e. compiler replacing the type).

> - the internal type is still required (or plenty of special 
> cases) so that for example errors message display the type 
> representation correctly and not as lowered.

So perhaps the internal type could then be a wrapper over struct 
one? Could that solve the issue with internal representation, and 
perhaps the type system (previous statement)?

> - CTFE must use the new struct template too?

What do you mean by that?

> - apparently (recently read that elsewhere) control of the 
> bound checks cannot be based on `version`

Why can't they?