error: unused return value of `foo` that must be used
  --> $DIR/must_use-unit.rs:13:5
   |
LL |     foo();
   |     ^^^^^^
   |
note: the lint level is defined here
  --> $DIR/must_use-unit.rs:2:9
   |
LL | #![deny(unused_must_use)]
   |         ^^^^^^^^^^^^^^^

error: unused return value of `bar` that must be used
  --> $DIR/must_use-unit.rs:15:5
   |
LL |     bar();
   |     ^^^^^^

error: aborting due to 2 previous errors