error: `derive` may only be applied to structs, enums and unions
  --> $DIR/issue-43023.rs:4:5
   |
LL |     #[derive(Debug)]
   |     ^^^^^^^^^^^^^^^^

error: `derive` may only be applied to structs, enums and unions
  --> $DIR/issue-43023.rs:11:5
   |
LL |     #[derive(Debug)]
   |     ^^^^^^^^^^^^^^^^

error: `derive` may only be applied to structs, enums and unions
  --> $DIR/issue-43023.rs:16:5
   |
LL |     #[derive(Debug)]
   |     ^^^^^^^^^^^^^^^^

error: aborting due to 3 previous errors