rust-lang/rust-clippy

Always true expressions in if expressions

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#1593 opened on Mar 3, 2017

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 (3 comments) (0 reactions) (1 assignee)Rust (10,406 stars) (1,391 forks)batch import
A-lintL-correctnessT-middlegood first issue

Description

I'd like Clippy to find this problem in the code, this expression is always true, and Clippy should also suggest the usage of && here instead:

fn foo1a(name: &str) {
    if name != "Min" || name != "Max" {}
}

Another example:

fn foo1b(x: i32) -> bool {
    x > 10 || x < 25
}

Contributor guide

Tech stack
rust
Domain
tooling
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 programmingClippy lint developmentAST basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40
Research direction
The issue requests a new lint to detect always true expressions like `name != "Min" || name != "Max"`. The issue is assigned to Dominic Moser. To implement, you'd need to understand Clippy's lint structure, likely adding a new lint in the `clippy lints` crate. The examples are clear, but ensure the lint doesn't produce false positives. Check existing lints like `if not else` for patterns. No linked PRs or additional comments provide further guidance.