error[E0308]: mismatched types
  --> $DIR/tuple-mismatch.rs:6:20
   |
LL |         yield ((), ());
   |                    ^^ expected tuple, found `()`
   |
   = note:  expected tuple `((), ())`
           found unit type `()`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0308`.