rust/src/test/compile-fail/pattern-macro-hygiene.rs

// 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 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

#![feature(macro_rules)]

macro_rules! foo ( () => ( x ) );

fn main() {
    let foo!() = 2;
    x + 1; //~ ERROR unresolved name `x`
}