Shared via Rust Playground

playground.rs

#![feature(raw)]

use std::raw::TraitObject;
use std::mem;

trait Foo {
    fn f(&self);
}

struct Bar;

impl Foo for Bar {
    fn f(&self) { println!("ok") }
}

fn erase<'a, T: ?Sized>(r: &'a T) -> TraitObject { unsafe { mem::transmute_copy(&r) } }
fn recover<'a, T: ?Sized>(r: TraitObject) -> &'a T { unsafe { mem::transmute_copy(&r) } } 

fn erase_foo<'a>(r: &'a Foo) -> TraitObject { unsafe { mem::transmute(r) } }
fn recover_foo<'a>(r: TraitObject) -> &'a Foo { unsafe { mem::transmute(r) } } 

fn main() {
    let r: &Foo = &Bar;
    let x = erase(r);
    let xf = erase_foo(r);
    println!("{:?} {:?}", x.data, x.vtable);
    println!("{:?} {:?}", xf.data, xf.vtable);
    let y: &Foo = recover(x);
    let yf = recover_foo(xf);
    y.f();
    yf.f();
}