// Copyright 2014 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. pub trait Foo { fn foo(&self, ext_thing: &T); } pub trait Bar: Foo { } impl Bar for T { } pub struct Thing; impl Foo for Thing { fn foo(&self, _: &T) {} } #[inline(never)] fn foo(b: &Bar) { b.foo(&0_usize) } fn main() { let mut thing = Thing; let test: &Bar = &mut thing; //~ ERROR cannot convert to a trait object foo(test); }