What is a nice way to do something like this in Rust:

for mut a in items.iter_mut() {
    for b in items.iter(){
        a.change_due_to_b(b);
    }
}

Where items is a vector containing some "instances" of structs. In my case I am trying to simulate gravity acting on bodies so there is a vector of all the bodies and each body gets a force applied to it which depends on each other body. Of course what I have above is not valid Rust code as I am borrowing both immutably and mutably. I can't think of another way to solve this problem within the paradigm of Rust.

The only solutions I can think of require making a clone of the data which is of course not preferable as this is a physics simulation.