error[E0072]: recursive type `Bar` has infinite size
  --> $DIR/issue-3008-2.rs:2:1
   |
LL | struct Bar { x: Bar }
   | ^^^^^^^^^^      --- recursive without indirection
   |
help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to break the cycle
   |
LL | struct Bar { x: Box<Bar> }
   |                 ++++   +

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0072`.