rust-lang/rust-clippy

Lint for unused empty function value

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#15,957 opened on Oct 26, 2025

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 (10 comments) (0 reactions) (1 assignee)Rust (1,391 forks)batch import
C-bugI-false-negativegood first issue

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Description

What it does

Suggests turning let _unused = returns_nothing(); to returns_nothing();

Advantage

Increases code hygiene

Drawbacks

None

Example

let _unused: () = returns_nothing();

Could be written as:

returns_nothing();

Comparison with existing lints

No similar lints were found

Additional Context

A quick Github search shows around 116 thousand instances of the aforementioned example

Contributor guide

Research direction
Study existing Clippy lints such as `let unit value` or `unused unit` to learn the structure. Use `clippy utils` to detect `let` bindings where the expression has type `()`, then suggest replacing with a statement. Test with `cargo clippy` on sample code.
Tech stack
rust
Domain
developer experience
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
RustGit
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
75