rust-lang / rust-lang/rust-clippy
Lint for borrow_mut() while borrowing
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A-lint
E-hard
L-correctness
T-middle
T-MIR
- Dominant language
- Rust
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Description
Hello.
It would be nice to have a lint to check some cases of wrong borrow() and borrow_mut() at compile time.
For instance, the following example could trigger a warning:
use std::cell::RefCell;
fn borrow(cell: &RefCell<Option<bool>>) {
if let Some(_) = *cell.borrow() {
*cell.borrow_mut() = None;
}
}
fn main() {
let cell = RefCell::new(Some(true));
borrow(&cell);
}
Thanks to add this lint.
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 provided Rust example using RefCell, borrow(), and borrow_mut(). Investigate whether Clippy can detect this borrow pattern at compile time; done means a lint warns on the shown case without incorrectly flagging valid code.
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