error[E0038]: the trait `Map` cannot be made into an object --> $DIR/issue-26056.rs:20:13 | LL | as &dyn Map; | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `Map` 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/issue-26056.rs:9:12 | LL | trait Map: MapLookup<::Key> { | --- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ...because it uses `Self` as a type parameter | | | this trait cannot be made into an object... error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0038`.