error: unused implementer of `Iterator` that must be used --> $DIR/unused-supertrait.rs:9:5 | LL | it(); | ^^^^ | = note: iterators are lazy and do nothing unless consumed note: the lint level is defined here --> $DIR/unused-supertrait.rs:1:9 | LL | #![deny(unused_must_use)] | ^^^^^^^^^^^^^^^ error: aborting due to 1 previous error