Why is this an issue?

Functions with a long parameter list are difficult to use because maintainers must figure out the role of each parameter and keep track of their position.

fn set_coordinates(x1: i32, y1: i32, z1: i32, x2: i32, y2: i32, z2: i32) { // Noncompliant
    // ...
}

The solution can be to:

• Split the function into smaller ones

// Each function does a part of what the original setCoordinates function was doing, so confusion risks are lower
fn set_origin(x: i32, y: i32, z: i32) {
    // ...
}

fn set_size(width: i32, height: i32, depth: i32) {
    // ...
}

• Find a better data structure for the parameters that group data in a way that makes sense for the specific application domain

struct Point {
    x: i32,
    y: i32,
}

impl Point {
    fn new(x: i32, y: i32) -> Point {
        Point { x, y }
    }
}

fn set_coordinates(p1: &mut Point, p2: &Point) {
    // ...
}

This rule raises an issue when a function has more parameters than the provided threshold.

Resources

Documentation

• Clippy Lints - https://rust-lang.github.io/rust-clippy/master/index.html#too_many_arguments