ptr_arg lint could warn also with &PathBuf and &Path

[marcoieni]

What it does

The ptr_arg lint already warns you when you pass a &String to a function.

For example with this piece of code:

fn print(a: &String) {
    println!("{:?}", a);
}

fn main() {
    let a = "/home/marco".to_string();
    print(&a);
}

This warning is emitted:

It would be nice if it did the same for PathBuf and Path, because from my understanding, the same principle of String and str applies.

Example

use std::path::PathBuf;

fn print(a: &PathBuf) {
    println!("{:?}", a);
}

fn main() {
    let a: PathBuf = "/home/marco".into();
    print(&a);
}

Could be written as:

use std::path::{Path, PathBuf};

fn print(a: &Path) {
    println!("{:?}", a);
}

fn main() {
    let a: PathBuf = "/home/marco".into();
    print(&a);
}