rust-lang / rust-lang/rust-clippy

False positive `useless_asref` on `Result`

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#16,529 3 comments 0 reactions 1 assignee View on GitHub

@mikhailofff is already working on this.

Since Feb 14, 2026.

C-bug I-false-positive I-suggestion-causes-error
Dominant language
Rust
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Description

Summary

When .as_ref().map(Clone::clone) is used on Result<T, E>, clippy says that it's a useless as_ref and suggests replacing .as_ref().map(...) with .clone() (which changes the expression type from Result<T, &E> to Result<T, E>). I think rather it should complain about .map(Clone::clone) and suggest replacing it with .cloned(), which fixes the issue.

Lint Name

useless_asref

Reproducer

I tried this code:

fn main() {
    let r: Result<i32, i64> = Ok(1);
    let _r = r.as_ref().map(Clone::clone);
}

I saw this happen:

    Checking playground v0.0.1 (/playground)
warning: this call to `as_ref.map(...)` does nothing
 --> src/main.rs:3:14
  |
3 |     let _r = r.as_ref().map(Clone::clone);
  |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `r.clone()`
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/rust-1.93.0/index.html#useless_asref
  = note: `#[warn(clippy::useless_asref)]` on by default

Link to playground

I expected to see this happen:

No lint or complains about .map(Clone::clone).

Version
rustc 1.95.0-nightly (f889772d6 2026-02-05)
binary: rustc
commit-hash: f889772d6500faebcac5bb70fa44b5e6581c38cd
commit-date: 2026-02-05
host: x86_64-unknown-linux-gnu
release: 1.95.0-nightly
LLVM version: 22.1.0
Additional Labels

@rustbot label +I-suggestion-causes-error

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