Yeah, Rust usually eschews the sort of non-local reasoning that would require. It would be harder to implement, and harder for the programmer to think about to

Yeah, Rust usually eschews the sort of non-local reasoning that would require. It would be harder to implement, and harder for the programmer to think about too, especially with changes from afar as you say. Also, auto-`Deref` can make this even more surprising! If you have some `foo: Rc<Foo>`, then `&foo.bar` borrows the whole struct via `Rc::deref(&self)`. You can sometimes get around this by taking a full dereferenced borrow yourself -- `let foo: &Foo = &*foo;` -- and then work with partial borrows from that. Same goes for `DerefMut`, or really more so since `&mut` is exclusive.