1 #![deny(unused_must_use)]
2 #![feature(arbitrary_self_types)]
4 use std::iter::Iterator;
5 use std::future::Future;
7 use std::task::{Context, Poll};
9 use std::unimplemented;
13 impl Future for MyFuture {
16 fn poll(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<u32> {
21 fn iterator() -> impl Iterator {
22 std::iter::empty::<u32>()
25 fn future() -> impl Future {
29 fn square_fn_once() -> impl FnOnce(u32) -> u32 {
33 fn square_fn_mut() -> impl FnMut(u32) -> u32 {
37 fn square_fn() -> impl Fn(u32) -> u32 {
42 iterator(); //~ ERROR unused implementer of `Iterator` that must be used
43 future(); //~ ERROR unused implementer of `Future` that must be used
44 square_fn_once(); //~ ERROR unused implementer of `FnOnce` that must be used
45 square_fn_mut(); //~ ERROR unused implementer of `FnMut` that must be used
46 square_fn(); //~ ERROR unused implementer of `Fn` that must be used