fn f(a: &mut [u8]) -> &mut [u8] {
    match a {
        [b @ ..] if false => b,
        aa => aa,
    }
}

fn f1(a: &mut [u8]) -> &mut [u8] {
    match a {
        b if false => b,
        aa => aa,
    }
}

fn f2(a: &mut [u8]) -> &mut [u8] {
    match a {
        b if false => b,
        [aa @ ..] => aa,
    }
}

fn f3(a: &mut [u8]) -> &mut [u8] {
    match a {
        [..] if false => a,
        [aa @ ..] => aa,
    }
}

fn original(a: &mut [u8]) -> &mut [u8] {
    match a {
        [.., b] if false => core::slice::from_mut(b),
        [aa @ ..] => aa,
        //^ cannot borrow `a[..]` as mutable more than once at a time
    }
}