error[E0371]: the object type `(dyn Foo + 'a)` automatically implements the trait `Foo` --> $DIR/issue-20939.rs:3:1 | LL | impl<'a> Foo for dyn Foo + 'a {} | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `(dyn Foo + 'a)` automatically implements trait `Foo` error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0371`.