// Copyright 2012 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. #![feature(unboxed_closures)] use std::ops::FnMut; struct S { x: isize, y: isize, } impl FnMut for S { extern "rust-call" fn call_mut(&mut self, z: isize) -> isize { self.x + self.y + z } } impl FnOnce for S { type Output = isize; extern "rust-call" fn call_once(mut self, z: isize) -> isize { self.call_mut(z) } } fn main() { let mut s = S { x: 1, y: 2, }; drop(s(3)) //~ ERROR cannot use call notation }