// Copyright 2015 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. use std::any::Any; fn main() { fn bar(x:i32) ->i32 { 3*x }; let b:Box = Box::new(bar as fn(_)->_); b.downcast_ref::_>(); //~^ ERROR cannot determine a type for this expression: unconstrained type }