error[E0072]: recursive types `Baz` and `Foo` have infinite size --> $DIR/sized-cycle-note.rs:1:1 | LL | struct Baz { q: Option } | ^^^^^^^^^^ --- recursive without indirection LL | LL | struct Foo { q: Option } | ^^^^^^^^^^ --- recursive without indirection | help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to break the cycle | LL ~ struct Baz { q: Option> } LL | LL ~ struct Foo { q: Option> } | error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0072`.