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[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: aborting due to 5 previous errors For more information about this error, try `rustc --explain E0667`.