error: `?` may only modify trait bounds, not lifetime bounds
  --> $DIR/issue-68890-2.rs:1:11
   |
LL | type X = (?'a) +;
   |           ^

error: expected trait bound, not lifetime bound
  --> $DIR/issue-68890-2.rs:1:11
   |
LL | type X = (?'a) +;
   |           ^^^

error: aborting due to 2 previous errors