src/test/ui/issues/issue-20939.stderr

   1 error[E0371]: the object type `(dyn Foo + 'a)` automatically implements the trait `Foo`
   2   --> $DIR/issue-20939.rs:3:1
   3    |
   4 LL | impl<'a> Foo for dyn Foo + 'a {}
   5    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `(dyn Foo + 'a)` automatically implements trait `Foo`
   6
   7 error: aborting due to previous error
   8
   9 For more information about this error, try `rustc --explain E0371`.