warning: method `tr2` is never used
  --> $DIR/rpit.rs:6:20
   |
LL | trait Tr2<'a> { fn tr2(self) -> &'a Self; }
   |       ---          ^^^
   |       |
   |       method in this trait
   |
   = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default

warning: 1 warning emitted