Why use 1usize instead of 0usize in unreachable?

[playXE]

Why use 1usize instead of 0usize there :

#[inline]
pub unsafe fn unreachable() -> ! {
    enum Void {}
    let x: &Void = mem::transmute(1usize);
    match *x {}
}

If this function should trigger UB?

[emilio]

Doesn't really matter, to be clear, right?

It creates a null reference and dereferences it, so it's clearly UB regardless of the value of the reference.

Anyhow on trunk this has been replaced by std::hint::unreachable_unchecked.