error: cannot find derive macro `Sync` in this scope
  --> $DIR/issue-33571.rs:2:10
   |
LL |          Sync,
   |          ^^^^
   |
note: unsafe traits like `Sync` should be implemented explicitly
  --> $DIR/issue-33571.rs:2:10
   |
LL |          Sync,
   |          ^^^^

error: aborting due to previous error