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

error: aborting due to previous error