Remove never option in argument position

[taiki-e]

This removes never option in argument position.

It is easier and more flexible to define your own enum using #[enum_derive] attribute.

#[enum_derive(Iterator)]
enum Either<A, B> {
    A(A),
    B(B),
}

fn foo(x: i32) -> impl Iterator<Item = i32> {
    match x {
        0 => loop {
             return Either::A(1..10);
        },
        1 => loop {
            panic!()
        },
        _ => loop {
            return Either::B(vec![5, 10].into_iter());
        },
    }
}

[taiki-e]

bors r+

[bors]

Build succeeded

• taiki-e.auto_enums