error[E0308]: mismatched types
  --> $DIR/issue-10176.rs:12:5
   |
LL | fn f() -> isize {
   |           ----- expected `isize` because of return type
LL |     (return 1, return 2)
   |     ^^^^^^^^^^^^^^^^^^^^ expected isize, found tuple
   |
   = note: expected type `isize`
              found type `(!, !)`

error: aborting due to previous error

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