//# run
main() {
    let v: u64;
    let read_ref: &mut u64;
    let assign_ref: &mut u64;
    let no: u64;
label b0:
    v = 5;
    read_ref = &mut v;
    assign_ref = copy(read_ref);
    *copy(assign_ref) = 0;
    assert(*copy(assign_ref) == 0, 42);
    no = *move(read_ref); // valid to read reference after assiging a copy!
    _ = move(assign_ref);
    return;
}