1 error[E0308]: mismatched types
2 --> $DIR/issue-89275.rs:28:29
4 LL | let other: &mut Other = downcast();
5 | ---------- ^^^^^^^^^^ types differ in mutability
9 = note: expected mutable reference `&mut Other`
12 error: aborting due to previous error
14 For more information about this error, try `rustc --explain E0308`.