error: expected `*`
  --> tests/compile-fail/missing_deref.rs:14:24
   |
14 |             Symbol(mb!(s)) => {},
   |                        ^

warning: unreachable pattern
  --> tests/compile-fail/missing_deref.rs:15:13
   |
15 |             _ => panic!(),
   |             ^ no value can reach this
   |
note: multiple earlier patterns match some of the same values
  --> tests/compile-fail/missing_deref.rs:15:13
   |
12 |             Nil => {},
   |             --- matches some of the same values
13 |             Cons(_, _) => {},
   |             ---------- matches some of the same values
14 |             Symbol(mb!(s)) => {},
   |             -------------- matches some of the same values
15 |             _ => panic!(),
   |             ^ collectively making this unreachable
   = note: `#[warn(unreachable_patterns)]` on by default