error[E0631]: type mismatch in coroutine arguments
  --> $DIR/issue-88653.rs:8:22
   |
LL | fn foo(bar: bool) -> impl Coroutine<(bool,)> {
   |                      ^^^^^^^^^^^^^^^^^^^^^^^ expected due to this
...
LL |     |bar| {
   |     ----- found signature defined here
   |
   = note: expected coroutine signature `fn((bool,)) -> _`
              found coroutine signature `fn(bool) -> _`

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0631`.