error: invalid `?` in type
  --> $DIR/trailing-question-in-type.rs:3:16
   |
LL | fn foo() -> i32? {
   |                ^ `?` is only allowed on expressions, not types
   |
help: if you meant to express that the type might not contain a value, use the `Option` wrapper type
   |
LL | fn foo() -> Option<i32> {
   |             +++++++   ~

error: invalid `?` in type
  --> $DIR/trailing-question-in-type.rs:4:15
   |
LL |     let x: i32? = Some(1);
   |               ^ `?` is only allowed on expressions, not types
   |
help: if you meant to express that the type might not contain a value, use the `Option` wrapper type
   |
LL |     let x: Option<i32> = Some(1);
   |            +++++++   ~

error: aborting due to 2 previous errors