rust-lang/rust-clippy

Enhancements for `manual_flatten`

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#6,676 opened on Feb 5, 2021

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Description

Enhancements for manual_flatten

  1. for_each

    Before:

    iter.for_each(|o| {
    if let Some(x) = o { //.. }
})

    After

    iter.flatten().for_each(|o| //..)

  2. nested loops

    Before:

    for x in vec![vec![1]] {
    for y in x {
        //..  x is not used again
    }
}

    After:

    for x in vec![vec![1]].into_iter().flatten() {
    // ..
}

Contributor guide

Research direction
Implement new patterns for manual flatten lint: detect `for each` with Option and flatten, and nested loops whose inner loop can be replaced with flatten. Study existing manual flatten implementation in clippy and add new match arms.
Tech stack
rust
Domain
developer experiencetooling
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Rust
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60