error[E0225]: only auto traits can be used as additional traits in a trait object
  --> $DIR/issue-22560.rs:9:23
   |
LL | type Test = dyn Add + Sub;
   |                 ---   ^^^ additional non-auto trait
   |                 |
   |                 first non-auto trait
   |
   = help: consider creating a new trait with all of these as supertraits and using that trait here instead: `trait NewTrait: Add + Sub {}`
   = note: auto-traits like `Send` and `Sync` are traits that have special properties; for more information on them, visit <https://doc.rust-lang.org/reference/special-types-and-traits.html#auto-traits>

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0225`.