On Borrow Checking

[Walter Bright]

On 5/10/2025 1:17 PM, Richard (Rikki) Andrew Cattermole wrote:
> There is also the mess with ``return ref`` vs ``return``, that can be written as 
> ``return scope`` and ``scope return``.

That came about because of the existence of `ref`. Consider `ref int* p`. How do 
you model the scope-ness of the reference and the scope-ness of the pointer?


> These both have the same escape set, just a different relationship strength.

Strength??


> This is of course one of the worst design decisions the D community has ever 
> implemented with full regret by all parties involved! :)

The concept behind it works fine. The trouble comes with the complexity of all 
the pointer constructions, like the invisible use of `this` references.


> This is also a good time to remember that DIP1000 only understands no escape, 
> escape into return value OR this pointer.

That's sufficient to prevent an escaping pointer to the stack. It's quite solid. 
If you disagree, post a code snippet demonstrating it.


> No multiple output support, which severely limits its capabilities.

It does not severely limit it. Even the Rust manual says it's a rare case. It's 
a minor inconvenience that can be refactored away.