rust-lang / rust-lang/rust-clippy

needless nested `match`

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A-lint
Dominant language
Rust
Stars
13.5k
Forks
2.2k
Avg merge
2d 10h
Merged PRs (30d)
32

Description

What it does

Warn on a nested match that can be merged.

Advantage
  • Clarity
  • Concise
Drawbacks
  • Could be less readable in non-trivial cases (not Option/Result).
Example
match token {
    Ok(token) => match token {
        Token::A | Token::B => { ... }
    }
    Err(err) => {}
}

Could be written as:

match token {
    Ok(Token::A | Token::B) => { ... }
    Err(err) => {}
}

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start from the nested-match examples in this issue and compare them with existing Clippy lint patterns. Clarify which nested matches are safe to merge and which non-trivial cases should be excluded. Done means the proposed lint covers the shown transformation and tests its intended boundaries.

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

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