rust-lang / rust-lang/rust-clippy

Detect needless use of `let else` with trailing semicolon

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A-lint
Dominant language
Rust
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Description

What it does

Detects uses of let else that could be handled through the ? operator.

Advantage
  • The ? operator is meant for error handling, use it when possible
Drawbacks

No response

Example
let Some(x) = y else { return None; };

Could be written as:

let x = y?;

This could also be extended to stuff like:

let Some(x) = y else { return Err(err); };

Could be written as:

let x = y.ok_or(err)?;

or

let x = y.ok_or_else(|| 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 by reviewing the issue's let else examples and the proposed ?, ok_or, and ok_or_else alternatives. Determine the relevant rust-clippy lint entry point and tests, then confirm that the requested patterns are detected without flagging cases where the rewrite is not equivalent.

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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