DIP1000: 'return scope' ambiguity and why you can't make opIndex work

[ag0aep6g]

On Saturday, 19 June 2021 at 14:39:01 UTC, Dukc wrote:
> It's simpler and better if `return` attribute outside the 
> parameter list always binds to `this`. Unless there is some 
> reason you might want to annotate the return type as `return`? 
> I can't think of any.

I think you misunderstand. `return` does bind to `this`. But it 
can bind to two different aspects of `this`: (1) `ref` or (2) 
`scope`.

Currently, you cannot freely choose which aspect of `this` you 
want to be `return`. The `opIndex` example fails because `return` 
is applied to the wrong aspect, and the programmer can't override 
it.