error[E0072]: recursive type `Baz` has infinite size --> $DIR/issue-17431-2.rs:1:1 | LL | struct Baz { q: Option } | ^^^^^^^^^^ ----------- recursive without indirection | | | recursive type has infinite size | help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `Baz` representable | LL | struct Baz { q: Option> } | ++++ + error[E0072]: recursive type `Foo` has infinite size --> $DIR/issue-17431-2.rs:4:1 | LL | struct Foo { q: Option } | ^^^^^^^^^^ ----------- recursive without indirection | | | recursive type has infinite size | help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `Foo` representable | LL | struct Foo { q: Option> } | ++++ + error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0072`.