// 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::ops::AddAssign; struct Int(i32); impl AddAssign for Int { fn add_assign(&mut self, _: i32) { unimplemented!() } } fn main() { let mut x = Int(0); x += 1; //~^ error: overloaded augmented assignments are not stable // | help: add #![feature(augmented_assignments)] to the crate root to enable }