rust-lang/rust-clippy

Manual Duration::{as_nanos,as_milis,as_secs_f64,as_secs_f32} implementation

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#6068 opened on Sep 20, 2020

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 (4 comments) (0 reactions) (1 assignee)Rust (10,406 stars) (1,391 forks)batch import
C-enhancementgood first issue

Description

What it does

Recognize cases of manual re-implementation of the builtin as_nanos and as_secs_f64 and as_secs_f32 functions on Duration.

Categories

  • Kind: complexity, sometimes also correctness

Drawbacks

MSRV issues, implementing the suggestion might increase the MSRV.

Example

let nanos = diff.as_secs() * 1_000_000_000 + diff.subsec_nanos() as u64;
let milis = diff.as_secs() * 1_000 + diff.subsec_milis() as u64;
let secs_f64 = (diff.as_secs() as f64 * 1_000.0 + diff.subsec_milis() as f64) / 1000.0;
let secs_f64 = diff.as_secs() as f64 + diff.subsec_milis() as f64 / 1_000.0;
let secs_f64 = diff.as_secs() as f64 + diff.subsec_nanos() as f64 / 1_000_000_000.0;

Could be written as:

let nanos = diff.as_nanos() as u64;
let milis = diff.as_millis() as u64;
let secs_f64 = diff.as_secs_f64();
let secs_f64 = diff.as_secs_f64();
let secs_f64 = diff.as_secs_f64();

Contributor guide

Tech stack
rust
Domain
toolingdeveloper experience
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.
blocked
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Rust programming languageClippy lint developmentDuration type
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
The issue requests a new lint for manual Duration method re implementations. To implement, a new lint file should be created in clippy lints/src/methods/ similar to existing lints like 'manual saturating arithmetic'. The lint should detect patterns like as secs() * 1 000 000 000 + subsec nanos() and suggest using builtin methods. Check the issue comments for any additional requirements or MSRV considerations.