Suggest zip + repeat_n instead of loop + clone

[SpriteOvO]

What it does

Using zip + repeat_n instead of loop + clone, we can reduce one unnecessary clone.

Advantage

• Performance, we could reduce 1 time unnecessary clone cost.

Drawbacks

• This requires changing the loop block to a .for_each() or introducing a .unwrap() call, even though it will never panic.
• This requires the loop range has .len() method.

Example

fn set_something<T: Clone>(value: T) {
    for prop in props.iter() {
        prop.set(value.clone());
    }
}

This function will clone value props.len() times.

If we change the implementation to use zip + repeat_n, we could reduce it to clone value props.len() - 1 times.

fn set_something<T: Clone>(value: T) {
    props
        .iter()
        .zip(std::iter::repeat_n(value, props.len()))
        .for_each(|prop, value| prop.set(value));
}

Or

fn set_something<T: Clone>(value: T) {
    let mut value = std::iter::repeat_n(value, props.len());
    for prop in props.iter() {
        prop.set(value.next().unwrap());
    }
}

Comparison with existing lints

No response

Additional Context

No response

[profetia]

I think repeat_n is just doing clone under the hood

[SpriteOvO]

@profetia Yes, but the point is that the argument value will not get dropped if repeat_n is used.

Playground: https://play.rust-lang.org/?version=stable&mode=debug&edition=2024&gist=40ce1fee5af7a1b2a6705c79dfcce13e