error[E0667]: `impl Trait` is not allowed in path parameters
  --> $DIR/impl_trait_projections.rs:12:51
   |
LL | fn projection_is_disallowed(x: impl Iterator) -> <impl Iterator>::Item {
   |                                                   ^^^^^^^^^^^^^

error[E0667]: `impl Trait` is not allowed in path parameters
  --> $DIR/impl_trait_projections.rs:19:9
   |
LL |     -> <impl Iterator as Iterator>::Item
   |         ^^^^^^^^^^^^^

error[E0667]: `impl Trait` is not allowed in path parameters
  --> $DIR/impl_trait_projections.rs:26:27
   |
LL |     -> <::std::ops::Range<impl Debug> as Iterator>::Item
   |                           ^^^^^^^^^^

error[E0667]: `impl Trait` is not allowed in path parameters
  --> $DIR/impl_trait_projections.rs:33:29
   |
LL |     -> <dyn Iterator<Item = impl Debug> as Iterator>::Item
   |                             ^^^^^^^^^^

error[E0223]: ambiguous associated type
  --> $DIR/impl_trait_projections.rs:12:50
   |
LL | fn projection_is_disallowed(x: impl Iterator) -> <impl Iterator>::Item {
   |                                                  ^^^^^^^^^^^^^^^^^^^^^ help: use fully-qualified syntax: `<impl Iterator as Trait>::Item`

error: aborting due to 5 previous errors

Some errors have detailed explanations: E0223, E0667.
For more information about an error, try `rustc --explain E0223`.