Do not suggest Rc::clone(x) over x.clone() when x is trait

[topecongiro]

Given the following code:

use std::rc::Rc;

trait Foo {}

struct Bar {}

impl Foo for Bar {}

fn foo(x: Rc<Foo>) {}

fn main() {
    let x = Rc::new(Bar{});
    foo(x.clone()); // foo(Rc::clone(&x)) will not work here.
}

cargo clippy gives a warning against using '.clone()' on a ref-counted pointer and suggests Rc::clone(&x). However the latter will not compile:

   |
13 |     foo(Rc::clone(&x));
   |                   ^^ expected trait Foo, found struct `Bar`
   |
   = note: expected type `&std::rc::Rc<Foo>`
              found type `&std::rc::Rc<Bar>`

[oli-obk]

Thanks for the bug report. This bug is already tracked under #2048

[topecongiro]

Oops, sorry for the noise.