error[E0277]: the trait bound `(): IteratorAlias` is not satisfied --> $DIR/issue-108072-unmet-trait-alias-bound.rs:10:7 | LL | f(()) | - ^^ the trait `Iterator` is not implemented for `()`, which is required by `(): IteratorAlias` | | | required by a bound introduced by this call | = note: required for `()` to implement `IteratorAlias` note: required by a bound in `f` --> $DIR/issue-108072-unmet-trait-alias-bound.rs:7:14 | LL | fn f(_: impl IteratorAlias) {} | ^^^^^^^^^^^^^ required by this bound in `f` error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0277`.