error: `must_not_suspend` attribute should be applied to a struct, enum, or trait
  --> $DIR/return.rs:5:1
   |
LL |   #[must_not_suspend]
   |   ^^^^^^^^^^^^^^^^^^^
LL | / fn foo() -> i32 {
LL | |     0
LL | | }
   | |_- is not a struct, enum, or trait

error: aborting due to previous error