Expand float_cmp to structs with PartialEq

Description

#[derive(PartialEq)]
struct Data {
    v: f64,
}

fn main() {
    let d1 = Data { v: 1.0 };
    let d2 = Data { v: 2.0 };

    // here should be a warning
    println!("{}", d1 == d2);
}

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.

half day

Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.

stale

ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.

clear

Prerequisites

Rust programmingClippy lint developmentPartialEq and float comparison

Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.

65

Research direction

Examine the current float cmp lint implementation in clippy lints/src/float cmp.rs. Identify how it detects direct float comparisons and extend it to detect comparisons of structs that derive PartialEq and contain float fields. Consider using trait resolution to check if the struct's PartialEq is derived and if any field type is f32 or f64. Then add a test case similar to the example in the issue.