error: unused implementer of `Iterator` that must be used --> $DIR/must_use-in-stdlib-traits.rs:42:4 | LL | iterator(); | ^^^^^^^^^^ | = note: iterators are lazy and do nothing unless consumed note: the lint level is defined here --> $DIR/must_use-in-stdlib-traits.rs:1:9 | LL | #![deny(unused_must_use)] | ^^^^^^^^^^^^^^^ error: unused implementer of `Future` that must be used --> $DIR/must_use-in-stdlib-traits.rs:43:4 | LL | future(); | ^^^^^^^^ | = note: futures do nothing unless you `.await` or poll them error: unused implementer of `FnOnce` that must be used --> $DIR/must_use-in-stdlib-traits.rs:44:4 | LL | square_fn_once(); | ^^^^^^^^^^^^^^^^ | = note: closures are lazy and do nothing unless called error: unused implementer of `FnMut` that must be used --> $DIR/must_use-in-stdlib-traits.rs:45:4 | LL | square_fn_mut(); | ^^^^^^^^^^^^^^^ | = note: closures are lazy and do nothing unless called error: unused implementer of `Fn` that must be used --> $DIR/must_use-in-stdlib-traits.rs:46:4 | LL | square_fn(); | ^^^^^^^^^^^ | = note: closures are lazy and do nothing unless called error: aborting due to 5 previous errors