From what I understand, the following code is problematic because root is borrowed both mutably and immutably inside a loop. However, the error message is a bit more cryptic, because it seems to also involve the unrelated variable scene.

    let mut root = Root::new(device, queue, surface, &config, playback);
    let mut scene = Scene { instances: vec![] };
    let mut hud = Hud {};
    loop {
      update(&mut root);
      sync(&root, &mut scene, &mut hud);
      render(&root, &scene, &hud);
    }

Here is the diagnostic.

error[E0502]: cannot borrow `root` as mutable because it is also borrowed as immutable
  --> src\main.rs:62:22
   |
62 |       update::update(&mut root);
   |                      ^^^^^^^^^ mutable borrow occurs here
63 |       sync::sync(&root, &mut scene, &mut hud);
   |                  -----  ---------- immutable borrow later used here
   |                  |
   |                  immutable borrow occurs here

Is the checker really complaining about scene? Why? What's the deal with scene?

Thanks!

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