error[E0072]: recursive type `Expr` has infinite size
  --> $DIR/issue-32326.rs:15:1
   |
15 | enum Expr { //~ ERROR E0072
   | ^^^^^^^^^ recursive type has infinite size
16 |             //~| NOTE recursive type has infinite size
17 |     Plus(Expr, Expr),
   |          ----- ----- recursive without indirection
   |          |
   |          recursive without indirection
   |
   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `Expr` representable

error: aborting due to previous error