error[E0308]: mismatched types
  --> $DIR/match-struct.rs:6:9
   |
LL |     match (S { a: 1 }) {
   |           ------------ this expression has type `S`
LL |         E::C(_) => (),
   |         ^^^^^^^ expected struct `S`, found enum `E`

error: aborting due to previous error

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