error[E0038]: the trait `Bar` cannot be made into an object --> $DIR/object-safety-mentions-Self.rs:24:5 | 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-mentions-Self.rs:11:22 | LL | trait Bar { | --- this trait cannot be made into an object... LL | fn bar(&self, x: &Self); | ^^^^^ ...because method `bar` references the `Self` type in this parameter = help: consider moving `bar` to another trait = note: required for `&T` to implement `CoerceUnsized<&dyn Bar>` = note: required by cast to type `&dyn Bar` error[E0038]: the trait `Baz` cannot be made into an object --> $DIR/object-safety-mentions-Self.rs:30:5 | LL | t | ^ `Baz` 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-mentions-Self.rs:15:22 | LL | trait Baz { | --- this trait cannot be made into an object... LL | fn baz(&self) -> Self; | ^^^^ ...because method `baz` references the `Self` type in its return type = help: consider moving `baz` to another trait = note: required for `&T` to implement `CoerceUnsized<&dyn Baz>` = note: required by cast to type `&dyn Baz` error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0038`.