48 lines
1.0 KiB
Rust
48 lines
1.0 KiB
Rust
#![deny(unused_must_use)]
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#![feature(arbitrary_self_types)]
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use std::iter::Iterator;
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use std::future::Future;
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use std::task::{Context, Poll};
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use std::pin::Pin;
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use std::unimplemented;
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struct MyFuture;
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impl Future for MyFuture {
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type Output = u32;
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fn poll(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<u32> {
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Poll::Pending
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}
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}
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fn iterator() -> impl Iterator {
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std::iter::empty::<u32>()
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}
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fn future() -> impl Future {
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MyFuture
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}
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fn square_fn_once() -> impl FnOnce(u32) -> u32 {
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|x| x * x
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}
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fn square_fn_mut() -> impl FnMut(u32) -> u32 {
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|x| x * x
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}
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fn square_fn() -> impl Fn(u32) -> u32 {
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|x| x * x
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}
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fn main() {
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iterator(); //~ ERROR unused implementer of `Iterator` that must be used
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future(); //~ ERROR unused implementer of `Future` that must be used
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square_fn_once(); //~ ERROR unused implementer of `FnOnce` that must be used
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square_fn_mut(); //~ ERROR unused implementer of `FnMut` that must be used
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square_fn(); //~ ERROR unused implementer of `Fn` that must be used
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}
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