Hm, in that case you don't need to appeal to split_at_mut--reborrowing is sufficient to demonstrate that point. I think what czwarich is saying is more subtle-

Hm, in that case you don't need to appeal to split_at_mut--reborrowing is sufficient to demonstrate that point. I think what czwarich is saying is more subtle--that restrict allows "multiple readers, exclusive writer", which means that both shared pointers without UnsafeCell and mutable references in Rust are restrict in this sense, while &mut is more restrictive.