error[E0225]: only auto traits can be used as additional traits in a trait object --> $DIR/issue-32963.rs:8:31 | LL | size_of_copy::(); | ---- ^^^^ 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: Misc + Copy {}` = note: auto-traits like `Send` and `Sync` are traits that have special properties; for more information on them, visit error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0225`.