Use cube root function lint

[leonardo-m]

What it does

The lint suggest to replace a FP::powf() call with a different method call.

Lint Name

use_cube_root_function

Category

perf

Advantage

It's more precise, shorter and simpler.

Drawbacks

None, I think.

Example

#![warn(clippy::all)]
#![warn(clippy::nursery)]
#![warn(clippy::pedantic)]
fn main() {
    println!("{}", 1.5_f64.powf(1.0 / 3.0));
}

Could be written as:

#![warn(clippy::all)]
#![warn(clippy::nursery)]
#![warn(clippy::pedantic)]
fn main() {
    println!("{}", 1.5_f64.cbrt());
}

Also note that they output slightly different results. cbrt is more precise.

[oppiliappan]

this is already implemented in the imprecise_flops lint:

#![warn(clippy::imprecise_flops)]

fn main() {
    let x = 3f64;
    let _ = x.powf(1.0 / 3.0);
}

however, the lint does not seem to fire on:

#![warn(clippy::imprecise_flops)]

fn main() {
    let _ = 1.5_f64.powf(1.0 / 3.0);
}

which seems to be a separate issue.