error[E0053]: method `bar` has an incompatible type for trait
  --> $DIR/issue-13033.rs:18:30
   |
LL |     fn bar(&mut self, other: &mut Foo);
   |                              -------- type in trait
...
LL |     fn bar(&mut self, other: &Foo) {}
   |                              ^^^^ types differ in mutability
   |
   = note: expected type `fn(&mut Baz, &mut dyn Foo)`
              found type `fn(&mut Baz, &dyn Foo)`
help: consider change the type to match the mutability in trait
   |
LL |     fn bar(&mut self, other: &mut Foo) {}
   |                              ^^^^^^^^

error: aborting due to previous error

For more information about this error, try `rustc --explain E0053`.