mfbt/Unused.h
author Sylvestre Ledru <sledru@mozilla.com>
Mon, 06 Nov 2017 13:22:06 +0100
changeset 694109 98e2b4ee9775a2a2b5cc1bb8a390bfe901814f38
parent 598310 57b1aa6bfa2e43322cc2318916352a3fea19d19d
permissions -rw-r--r--
reformat all MozReview-Commit-ID: ApY4gI1IbKr

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef mozilla_unused_h
#define mozilla_unused_h

#include "mozilla/Attributes.h"
#include "mozilla/Types.h"

#ifdef __cplusplus

namespace mozilla {

//
// Suppress GCC warnings about unused return values with
//   Unused << SomeFuncDeclaredWarnUnusedReturnValue();
//
struct unused_t
{
  template <typename T>
  MOZ_ALWAYS_INLINE_EVEN_DEBUG void operator<<(const T& /*unused*/) const
  {
  }
};

extern MFBT_DATA const unused_t Unused;

}  // namespace mozilla

#endif  // __cplusplus

// An alternative to mozilla::Unused for use in (a) C code and (b) code where
// linking with unused.o is difficult.
#define MOZ_UNUSED(expr) \
  do {                   \
    if (expr) {          \
      (void)0;           \
    }                    \
  } while (0)

#endif  // mozilla_unused_h