rust-lang / rust-lang/rust-clippy
Lint reading an option and then overwriting it with `None`
Open
Nobody has claimed this yet.
A-lint
E-medium
L-unnecessary
T-middle
- Dominant language
- Rust
- Stars
- 13.5k
- Forks
- 2.2k
- Avg merge
- 2d 10h
- Merged PRs (30d)
- 32
Description
let old = some_option;
... code not reference `some_option`
some_option = None;
// use `old`
should be
let old = some_option.take();
Some care must be taken not to change behaviour. Accessing old and changing control flow (break, return) before some_option = None would be a legitimate case that the lint should not trigger on.
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
No implementation file, test, or entry point is named. Start by locating the Rust lint code and its tests, then trace how the lint identifies an option read followed by an unconditional assignment to None. Done means it suggests take() only when no use of the old value or control-flow change occurs before the assignment, with tests covering the legitimate exceptions.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- tooling
- Issue type
- Feature
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100