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

Dennis dkorpel at gmail.com
Tue Jul 6 09:45:49 UTC 2021

On Tuesday, 6 July 2021 at 09:37:30 UTC, Walter Bright wrote:
> It doesn't make sense to return either p or the address of p 
> with the same function. What kind of a function does that?

Here's an example:

But such a function should not be the norm. The point is that 
users can simply add `return` and think "now I'm allowed to 
return `this` or `&this.x` or `this.arr[0]` or whatever" without 
delving into the whole "am I returning an address or value and am 
I allowed to" conundrum.

> We could trick the code into doing that, but that would 
> introduce all kinds of bugs into the lifetime analysis code.

Do you have an example?

> The real problem is not being able to return the value of p as 
> a ref, if p is also passed by ref.
> I'm going to look into addressing that.


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