error[E0072]: recursive type `t1` has infinite size
  --> $DIR/type-recursive.rs:11:1
   |
LL | struct t1 { //~ ERROR E0072
   | ^^^^^^^^^ recursive type has infinite size
LL |     foo: isize,
LL |     foolish: t1
   |     ----------- recursive without indirection
   |
   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `t1` representable

error: aborting due to previous error

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