You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: macro_util.rs
    path of file: ./repos/zerocopy/src
    
    the code of the file until where you have to start completion: // Copyright 2022 The Fuchsia Authors
//
// Licensed under a BSD-style license <LICENSE-BSD>, Apache License, Version 2.0
// <LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0>, or the MIT
// license <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your option.
// This file may not be copied, modified, or distributed except according to
// those terms.

//! Utilities used by macros and by `zerocopy-derive`.
//!
//! These are defined here `zerocopy` rather than in code generated by macros or
//! by `zerocopy-derive` so that they can be compiled once rather than
//! recompiled for every in
    
    fn test_struct_has_padding() {
        // Test that, for each provided repr, `struct_has_padding!` reports the
        // expected value.
        macro_rules! test {
            (#[$cfg:meta] ($($ts:ty),*) => $expect:expr) => {{
                #[$cfg]
                struct Test($(#[allow(dead_code)] $ts),*);
                assert_eq!(struct_has_padding!(Test, $($ts),*), $expect);
            }};
            (#[$cfg:meta] $(#[$cfgs:meta])* ($($ts:ty),*) => $expect:expr) => {
                test!(#[$cfg] ($($ts),*) => $expect);
                test!($(#[$cfgs])* ($($ts),*) => $expect);
            };
        }

        test!(#[repr(C)] #[repr(transparent)] #[repr(packed)] () => false);
        test!(#[repr(C)] #[repr(transparent)] #[repr(packed)] (u8) => false);
        test!(#[repr(C)] #[repr(transparent)] #[repr(packed)] (u8, ()) => false);
        test!(#[repr(C)] #[repr(packed)] (u8, u8) => false);

        test!(#[repr(C)] (u8, AU64) => true);
        // Rust won't let you put `#[repr(packed)]` on a type which contains a
        // `#[repr(align(n > 1))]` type (`AU64`), so we have to use `u64` here.
        // It's not ideal, but it definitely has align > 1 on /some/ of our CI
        // targets, and this isn't a particularly complex macro we're testing
        // anyway.
        test!(#[repr(packed)] (u8, u64) => false);
    }