error: cannot check whether the hidden type of opaque type satisfies auto traits --> $DIR/auto-trait-leak.rs:18:10 | LL | send(cycle1().clone()); | ---- ^^^^^^^^^^^^^^^^ | | | required by a bound introduced by this call | = note: fetching the hidden types of an opaque inside of the defining scope is not supported. You can try moving the opaque type and the item that actually registers a hidden type into a new submodule note: opaque type is declared here --> $DIR/auto-trait-leak.rs:11:16 | LL | fn cycle1() -> impl Clone { | ^^^^^^^^^^ note: required by a bound in `send` --> $DIR/auto-trait-leak.rs:4:12 | LL | fn send(_: T) {} | ^^^^ required by this bound in `send` error: aborting due to 1 previous error