error: unconstrained opaque type
  --> $DIR/issue-109299-1.rs:10:10
   |
LL | type X = impl for<T> Fn() -> Lexer<T>::Cursor;
   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: `X` must be used in combination with a concrete type within the same crate

error: aborting due to 1 previous error

