rust-lang/rust-clippy

`never_loop`: Note why the loop will never loop.

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#16,056 opened on Nov 9, 2025

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Description

Description

The reason why a loop will never actually complete isn't always obvious (see #16054 for an example). For such cases it would be nice to have a note pointing out all the locations where this occurs. Obvious causes ideally wouldn't get any additional output.

Examples

loop {
    do_something();
    // No need to point this out.
    panic!();
}

// Imagine something less obvious.
let x = || Some(panic!());

loop {
    // Why doesn't this loop?
    x().unwrap();
}

Version

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Contributor guide

Research direction
Examine the `never loop` lint in clippy's source, look at its tests, and identify where a note can be added for non obvious infinite loops. Reference existing code for similar note patterns.
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
Rust
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65