error[E0506]: cannot assign to `a1` because it is borrowed --> $DIR/regions-pattern-typing-issue-19997.rs:7:13 | LL | match (&a1,) { | --- `a1` is borrowed here LL | (&ref b0,) => { LL | a1 = &f; | ^^^^^^^ `a1` is assigned to here but it was already borrowed LL | drop(b0); | -- borrow later used here error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0506`.