rust-lang / rust-lang/rust-clippy
Forbid modifying Cells in match guards
Open
Nobody has claimed this yet.
A-lint
E-medium
L-correctness
T-middle
- Dominant language
- Rust
- Stars
- 13.5k
- Forks
- 2.2k
- Avg merge
- 2d 10h
- Merged PRs (30d)
- 32
Description
To my horror I learned that
use std::cell::RefCell;
fn main() {
let x = RefCell::new(false);
match x {
ref y if y.replace(true) => println!("branch 1"),
ref y if y.replace(true) => println!("branch 2"),
_ => println!("default branch"),
}
}
actually works. We should be screaming loudly at the user
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reproducing the Rust example in the issue and then locate Clippy's existing lint entry points for match guards and interior mutability. The issue names no files or tests, so define the warning's scope and diagnostics before adding a regression test that demonstrates the example is reported.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- tooling
- Issue type
- Feature
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 25/100