error: item constrains opaque type that is not in its signature
  --> $DIR/issue-99387.rs:21:22
   |
LL | pub fn ohno<'a>() -> <&'a () as Tr>::Item {
   |                      ^^^^^^^^^^^^^^^^^^^^
   |
   = note: this item must mention the opaque type in its signature in order to be able to register hidden types
note: this item must mention the opaque type in its signature in order to be able to register hidden types
  --> $DIR/issue-99387.rs:21:8
   |
LL | pub fn ohno<'a>() -> <&'a () as Tr>::Item {
   |        ^^^^

error: aborting due to 1 previous error