error[E0503]: cannot use `u.c` because it was mutably borrowed --> $DIR/borrowck-union-borrow-nested.rs:24:21 | LL | let ra = &mut u.s.a; | ---------- borrow of `u.s.a` occurs here LL | let b = u.c; | ^^^ use of borrowed `u.s.a` LL | ra.use_mut(); | ------------ borrow later used here error: aborting due to previous error For more information about this error, try `rustc --explain E0503`.