rust-lang/rust-clippy

Always true expressions in if expressions

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#1,593 opened on Mar 3, 2017

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A-lintL-correctnessT-middlegood first issue

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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

Research direction
Study existing Clippy lints that detect logic errors, particularly those dealing with boolean expressions. Then implement a new lint that checks for always true/false conditions in if expressions using pattern matching on the AST. Write tests and ensure the lint suggests replacing `||` with `&&` when appropriate.
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.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
RustGit
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60