I'm afraid I don't know about Rust, but D has the scope parameter storage class for this. It enables the following compiler-enforced guarantee:

> The parameter must not escape the function call (e.g. by being assigned to a global variable). Ignored for any parameter that is not a reference type.

https://dlang.org/spec/function.html#scope-parameters

See also: https://dlang.org/blog/2023/10/02/crafting-self-evident-code... , https://news.ycombinator.com/item?id=37748543