`AtomicPtr` doesn't implement `std::fmt::Pointer`

[apasel422]

It can use a technique analogous to its Debug impl to do so.

[nagisa]

If we impl fmt::Pointer for AtomicPtr, we should also consider implementing Display for AtomicBool, AtomicIsize and AtomicUsize. I think not implementing these traits just yet is conscious.

[steveklabnik]

Triage: no change. here's a test case

use std::sync::atomic::AtomicPtr;

fn main() {
    let ptr = &mut 5;
    let some_ptr  = AtomicPtr::new(ptr);
    
    println!("{:p}", some_ptr);
}

[dtolnay]

I would be fine with adding these impls. The impls should access the atomic using the most restrictive memory ordering. Then if you want any other ordering there is a totally reasonable workaround:

println!("{:p}", some_ptr.load(Ordering::Relaxed));