| error[E0308]: mismatched types | |
| --> $DIR/retslot-cast.rs:13:5 | |
| | | |
| LL | inner(x) | |
| | ^^^^^^^^ expected trait `std::iter::Iterator<Item = ()>`, found trait `std::iter::Iterator<Item = ()> + std::marker::Send` | |
| | | |
| = note: expected enum `std::option::Option<&dyn std::iter::Iterator<Item = ()>>` | |
| found enum `std::option::Option<&dyn std::iter::Iterator<Item = ()> + std::marker::Send>` | |
| error: aborting due to previous error | |
| For more information about this error, try `rustc --explain E0308`. |