rust-lang/rust-clippy

Lint request: Prevent lifetimes that are only used for function output

Open

#1874 opened on Jul 5, 2017

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 (9 comments) (0 reactions) (0 assignees)Rust (10,406 stars) (1,391 forks)batch import
A-lintL-correctnessS-needs-discussionT-middlegood first issue

Description

The following:

fn lifetime<'a>() -> &'a str {
    "Why some people do that"
}

Can be more clearly written as this. Also, using 'static lifetime makes it clear that it was intended, especially in unsafe code where returning unbound lifetime may as well be a mistake.

fn lifetime() -> &'static str {
    "Why some people do that"
}

Contributor guide

Tech stack
rust
Domain
developer experiencetooling
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
Rust language basicsUnderstanding of lifetimesFamiliarity with clippy's lint creation process
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50
Research direction
The issue suggests a new lint to detect lifetimes that are only used in function outputs. Start by examining existing clippy lints related to lifetimes (e.g., in clippy lints/src/lifetimes.rs). Understand how clippy registers and implements lints. Look at the discussion in the issue comments for any additional constraints or alternatives. Consider the diagnostic output and potential false positives. Note that this is a feature request with no assignee, so it is available for contribution.