warning: method `do_something` is never used
  --> $DIR/generic-drop-trait-bound-15858.rs:9:8
   |
LL | trait Bar {
   |       --- method in this trait
LL |     fn do_something(&mut self);
   |        ^^^^^^^^^^^^
   |
   = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default

warning: 1 warning emitted