error[E0503]: cannot use `y.1` because it was mutably borrowed
  --> $DIR/match-cfg-fake-edges2.rs:11:17
   |
LL |     let r = &mut y.1;
   |             -------- borrow of `y.1` occurs here
...
LL |         (false, true) => 1,
   |                 ^^^^ use of borrowed `y.1`
LL |         (true, _) => {
LL |             r;
   |             - borrow later used here

error: aborting due to previous error

For more information about this error, try `rustc --explain E0503`.