error[E0631]: type mismatch in coroutine arguments
  --> $DIR/issue-88653.rs:8:22
   |
LL |   fn foo(bar: bool) -> impl Coroutine<(bool,)> {
   |                        ^^^^^^^^^^^^^^^^^^^^^^^ expected due to this
...
LL |       |bar| {
   |       -----
   |       |
   |  _____found signature defined here
   | |
LL | |
LL | |
LL | |         if bar {
LL | |             yield bar;
LL | |         }
LL | |     }
   | |_____- return type was inferred to be `{coroutine@$DIR/issue-88653.rs:15:5: 15:10}` 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`.