warning: this `Deref` implementation is covered by an implicit supertrait coercion
  --> $DIR/migrate-lint-deny-regions.rs:9:1
   |
LL | impl<'a> Deref for dyn Foo<'a> {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `dyn Foo<'_>` implements `Deref<Target = dyn Bar<'_>>` which conflicts with supertrait `Bar<'_>`
LL |
LL |     type Target = dyn Bar<'a>;
   |     ----------- target type is a supertrait of `dyn Foo<'_>`
   |
note: the lint level is defined here
  --> $DIR/migrate-lint-deny-regions.rs:2:9
   |
LL | #![warn(deref_into_dyn_supertrait)]
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^

warning: 1 warning emitted