rust-lang / rust-lang/rust-clippy
manual_map false positive, disregards ownership rules on Option types
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C-bug
I-false-positive
- Dominant language
- Rust
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Description
Summary
Clippy suggests replacing match on Option with map without regard to ownership rules.
Lint Name
manual_map
Reproducer
Consider this code:
let mut vector = vec![1, 2, 3];
let first = match vector.get(0) {
Some(_) => Some(vector.swap_remove(0)),
None => None
};
Clippy will suggest replacing match with map:
let mut vector = vec![1, 2, 3];
let first = vector.get(0).map(|_| vector.swap_remove(0));
Which does not compile.
Version
rustc 1.66.0 (69f9c33d7 2022-12-12)
binary: rustc
commit-hash: 69f9c33d71c871fc16ac445211281c6e7a340943
commit-date: 2022-12-12
host: x86_64-pc-windows-msvc
release: 1.66.0
LLVM version: 15.0.2
Additional Labels
No response
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 at the manual_map lint entry point and reproduce the Option example from the issue. Trace how the suggested map closure is checked against ownership, and consider the work complete when the lint no longer emits a suggestion that fails to compile for this case.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- tooling
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100