rust-lang/rust-clippy

Lint for unused arguments starting with a _

Open

#3219 opened on Sep 25, 2018

View on GitHub
 (11 comments) (0 reactions) (0 assignees)Rust (10,406 stars) (1,391 forks)batch import
A-lintL-stylegood first issue

Description

In response to this comment

I think the idea here would be to recommend removal of arguments that are ignored and never referenced.

On the flip side, I'm wondering if it would make sense to also lint for used arguments starting _ which recommends removing the _, because that came up in the same review.

Contributor guide

Tech stack
rust
Domain
tooling
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.
3-5 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
Familiarity with RustUnderstanding of Clippy's lint API
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
To implement this lint, examine how existing unused argument lints work in Clippy (e.g., `unused arguments`). The issue references a comment in PR #3203 which discusses the idea. The lint should detect function arguments that start with ` ` but are never used in the body, and optionally warn when a ` ` argument is used. Start by looking at the Clippy lint collection in `clippy lints/src/` and the Rust compiler's `rustc lint` API. The discussion may have further guidance on naming and behavior.