src/test/ui/hygiene/fields-definition.rs

// Copyright 2018 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(decl_macro)]

macro modern($a: ident) {
    struct Modern {
        a: u8,
        $a: u8, // OK
    }
}

macro_rules! legacy {
    ($a: ident) => {
        struct Legacy {
            a: u8,
            $a: u8, //~ ERROR field `a` is already declared
        }
    }
}

modern!(a);
legacy!(a);

fn main() {}