#![allow(dead_code, deprecated, unused_variables, unused_mut)]
use core::iter::Chain;
use core::slice;
use std::collections::{btree_set, BTreeSet};
use std::mem;
struct Foo<'a>(Chain<slice::Iter<'a, u8>, btree_set::Iter<'a, u8>>);
fn main() {
    let set = BTreeSet::<u8>::new();
    let slice: &[u8] = &[];
    let mut foo = Foo(slice.iter().chain(set.iter()));
    let _: Chain<_, _> = mem::take(&mut foo.0);
}