error[E0626]: borrow may still be in use when coroutine yields
  --> $DIR/pattern-borrow.rs:9:24
   |
LL |         if let Test::A(ref _a) = test {
   |                        ^^^^^^
LL |             yield ();
   |             -------- possible yield occurs here

error: aborting due to previous error

For more information about this error, try `rustc --explain E0626`.