error[E0038]: the trait `Foo` cannot be made into an object
  --> $DIR/foreign-dyn-error.rs:6:12
   |
LL |     let _: &dyn rpitit::Foo = todo!();
   |            ^^^^^^^^^^^^^^^^ `Foo` cannot be made into an object
   |
note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
  --> $DIR/auxiliary/rpitit.rs:4:21
   |
LL |     fn bar(self) -> impl Deref<Target = impl Sized>;
   |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait cannot be made into an object because method `bar` references an `impl Trait` type in its return type
   = help: only type `rpitit::Foreign` implements the trait, consider using it directly instead

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0038`.