// Copyright 2016 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. macro_rules! id { ($e:expr) => { $e } } fn main() { id!(x?); //~ error: the `?` operator is not stable (see issue #31436) y?; //~ error: the `?` operator is not stable (see issue #31436) }