"temporary value dropped while borrowed"-checker does not use NLL

[JonasAlaif]

A slightly modified version of Example 2 from here fails:

fn main() {
    let foo: &mut i32       = &mut 22;
    let mut r_a: &&mut i32  = & foo;
    let r_b: &mut &&mut i32 = &mut r_a;
    let r_c: &&mut i32      = & **r_b;

    // What is considered borrowed here?
    *r_b = &&mut 0;

    println!("{}", r_c);
}

with the following error:

error[E0716]: temporary value dropped while borrowed
  --> src/main.rs:8:13
   |
8  |     *r_b = &&mut 0;
   |             ^^^^^^- temporary value is freed at the end of this statement
   |             |
   |             creates a temporary which is freed while still in use
9  | 
10 |     println!("{}", r_c);
   |                    --- borrow later used here
   |
   = note: consider using a `let` binding to create a longer lived value

However, clearly r_c does not reborrow from r_a nor from r_b. Therefore, using it at the end should not affect either of these, but as we can see this is not the case. If one comments out the println! on line 10, then compilation succeeds as expected. Playground link here