error[E0308]: mismatched types
  --> $DIR/feature-gate-type_changing_struct_update.rs:20:11
   |
LL |         ..m1
   |           ^^ expected struct `State2`, found struct `State1`
   |
   = note: expected struct `Machine<State2>`
              found struct `Machine<State1>`

error: aborting due to previous error

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