error[E0186]: method `bar` has a `&self` declaration in the trait, but not in the impl
  --> $DIR/trait-impl-self-mismatch.rs:12:5
   |
LL |     fn bar(&self) {}
   |     ------------- `&self` used in trait
...
LL |     fn bar() {
   |     ^^^^^^^^ expected `&self` in impl

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0186`.