error[E0277]: `<impl Foo as Foo>::Bar` cannot be sent between threads safely
  --> $DIR/issue-79843-impl-trait-with-missing-bounds-on-async-fn.rs:14:20
   |
LL |     assert_is_send(&bar);
   |                    ^^^^ `<impl Foo as Foo>::Bar` cannot be sent between threads safely
...
LL | fn assert_is_send<T: Send>(_: &T) {}
   |                      ---- required by this bound in `assert_is_send`
   |
   = help: the trait `Send` is not implemented for `<impl Foo as Foo>::Bar`
help: introduce a type parameter with a trait bound instead of using `impl Trait`
   |
LL | async fn run<F: Foo>(_: &(), foo: F) -> std::io::Result<()> where <F as Foo>::Bar: Send {
   |             ^^^^^^^^              ^                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0277]: `<impl Foo as Foo>::Bar` cannot be sent between threads safely
  --> $DIR/issue-79843-impl-trait-with-missing-bounds-on-async-fn.rs:24:20
   |
LL |     assert_is_send(&bar);
   |                    ^^^^ `<impl Foo as Foo>::Bar` cannot be sent between threads safely
...
LL | fn assert_is_send<T: Send>(_: &T) {}
   |                      ---- required by this bound in `assert_is_send`
   |
   = help: the trait `Send` is not implemented for `<impl Foo as Foo>::Bar`
help: introduce a type parameter with a trait bound instead of using `impl Trait`
   |
LL | async fn run2<F: Foo>(_: &(), foo: F) -> std::io::Result<()> where <F as Foo>::Bar: Send {
   |              ^^^^^^^^              ^                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0277`.