1 error[E0308]: mismatched types
2 --> $DIR/retslot-cast.rs:13:5
4 LL | -> Option<&Iterator<Item=()>> {
5 | -------------------------- expected `Option<&dyn Iterator<Item = ()>>` because of return type
8 | ^^^^^^^^ expected trait `Iterator<Item = ()>`, found trait `Iterator<Item = ()> + Send`
10 = note: expected enum `Option<&dyn Iterator<Item = ()>>`
11 found enum `Option<&dyn Iterator<Item = ()> + Send>`
13 error: aborting due to previous error
15 For more information about this error, try `rustc --explain E0308`.