error[E0038]: the trait `Bar` cannot be made into an object --> $DIR/object-safety-sized-2.rs:16:5 | LL | t | ^ `Bar` cannot be made into an object | note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit --> $DIR/object-safety-sized-2.rs:9:18 | LL | trait Bar | --- this trait cannot be made into an object... LL | where Self : Sized | ^^^^^ ...because it requires `Self: Sized` = note: required for the cast from `&T` to `&dyn Bar` error: aborting due to previous error For more information about this error, try `rustc --explain E0038`.