1 error[E0072]: recursive type `ListNode` has infinite size
5 | ^^^^^^^^^^^^^^^ recursive type has infinite size
7 LL | tail: Option<ListNode>,
8 | ---------------------- recursive without indirection
10 = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `ListNode` representable
12 error: aborting due to previous error
14 For more information about this error, try `rustc --explain E0072`.