rust-lang/rust-clippy

lint variable assignments that could be part of a method/field chain

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#2,035 opened on Sep 9, 2017

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A-lintL-unnecessaryT-middlegood first issue

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Description

let x = foo.bar;
let y = x.met();

Should be

let y = foo.bar.met();

If x is not used anywhere else

Contributor guide

Research direction
Study Clippy's lint creation guide, then implement a lint that detects when a variable is assigned from a field/method call and only used in a single subsequent method chain. Use AST patterns and maybe data flow analysis to ensure the variable is not used elsewhere. Emit a suggestion to inline the chain.
Tech stack
rust
Domain
devtools
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.
3-5 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
RustGitClippy development setup
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30