On Borrow Checking

[jmh530]

On Friday, 2 May 2025 at 10:14:34 UTC, Dukc wrote:
>
> There's a difference.
>
> In Rust, as I understand it, if you have a function like
>
> ```Rust
> fn free(ptr: MyCustomPointer)
> {   // ...
> }
> ```
>
> it is 100% safe to use. The compiler will not let you 
> double-free or use after free, unless you use the `unsafe` 
> block to do so.
>
> But you can't have
>
> ```D
> @trusted void free(MyCustomPointer ptr)
> {   // ...
> }
> ```
>
> in D because it would be unsafe to use from a non-`@live` 
> function.
>
> If we had a way to say that "this function can be called from 
> `@safe`, if and only if it's usage is guarded with `@live`" 
> then it would be equal to the Rust borrow checker.

I was trying to make this point before, but think you do it 
better here.