FP redundant_iter_cloned on collecting async block capture reference

[eareimu]

Summary

as tittle

Lint Name

redundant_iter_cloned

Reproducer

I tried this code:

#[derive(Clone)]
struct Foo;

impl Foo {
    async fn foo(&self) {}
}

let _futures = {
    let map: HashMap<(), Foo> = HashMap::new();

    map.values()
        .cloned()
        .map(|foo| async move { foo.foo().await })
        .collect::<Vec<_>>()
};

I saw this happen:

warning: unneeded cloning of iterator items
   --> qconnection/src/traversal.rs:233:13
    |
233 | /             map.values()
234 | |                 .cloned()
235 | |                 .map(|foo| async move { foo.foo().await })
    | |__________________________________________________________^
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#redundant_iter_cloned
help: try
    |
233 ~             map.values()
234 +                 .map(|foo| async move { foo.foo().await })
    |

Adopting the suggestion will cause a compilation error.

Interestingly, if Foo implements Copy, the warning will not appear.

Version

rustc 1.95.0-nightly (d940e5684 2026-01-19)
binary: rustc
commit-hash: d940e56841ddcc05671ead99290e35ff2e98369f
commit-date: 2026-01-19
host: x86_64-unknown-linux-gnu
release: 1.95.0-nightly
LLVM version: 21.1.8

Additional Labels

No response