rust-lang/rust-clippy

Suggestion: borrowing a RefCell in funarg position

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#4,632 opened on Oct 4, 2019

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A-lintT-middlegood first issue

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Description

I recently came across this fun correctness bug in my code: https://github.com/rust-lang/rust/issues/65086.

I’m not sure how I could have known this without asking a compiler developer. Can we add a lint prohibiting RefCell borrows in funarg position since they prevent mutable borrows further down the stack?

Contributor guide

Research direction
Investigate the implementation of a new lint in Clippy that warns when borrowing a RefCell in function argument position. Study existing lints for patterns and follow the Clippy contribution guide.
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.
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.
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.
65