error[E0277]: the trait bound `(): Trait<1>` is not satisfied --> $DIR/unevaluated-const-impl-trait-ref.rs:20:13 | LL | needs::<1>(); | ^ the trait `Trait<1>` is not implemented for `()` | = help: the following other types implement trait `Trait`: `()` implements `Trait<0>` `()` implements `Trait<2>` note: required by a bound in `needs` --> $DIR/unevaluated-const-impl-trait-ref.rs:10:38 | LL | fn needs() where (): Trait {} | ^^^^^^^^ required by this bound in `needs` error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0277`.