1 error[E0596]: cannot borrow data in a `&` reference as mutable
2 --> $DIR/issue-52240.rs:9:27
4 LL | if let (Some(Foo::Bar(ref mut val)), _) = (&arr.get(0), 0) {
5 | ^^^^^^^^^^^ cannot borrow as mutable
7 error: aborting due to previous error
9 For more information about this error, try `rustc --explain E0596`.