error[E0499]: cannot borrow `y.0` as mutable more than once at a time --> $DIR/borrowck-anon-fields-struct.rs:29:11 | LL | Y(ref mut a, _) => a | --------- first mutable borrow occurs here ... LL | Y(ref mut b, _) => b | ^^^^^^^^^ second mutable borrow occurs here ... LL | *a += 1; | ------- first borrow later used here error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0499`.