error[E0308]: mismatched types
  --> $DIR/unexpected-return-on-unit.rs:19:5
   |
18 | fn bar() {
   |          - expected `()` because of this default return type
19 |     foo()
   |     ^^^^^ expected (), found usize
   |
   = note: expected type `()`
              found type `usize`
help: did you mean to add a semicolon here?
   |     foo();
help: possibly return type missing here?
   | fn bar() -> usize {

error: aborting due to previous error(s)