error: the `min` method cannot be invoked on `&dyn Iterator` --> $DIR/imm-ref-trait-object.rs:2:8 | LL | t.min().unwrap() | ^^^ | help: you need `&mut dyn Iterator` instead of `&dyn Iterator` | LL | fn test(t: &mut dyn Iterator) -> u64 { | +++ error: aborting due to 1 previous error