mfbt/Unused.h
author David Major <dmajor@mozilla.com>
Mon, 03 Jun 2019 20:30:31 +0000
changeset 536320 44b86ef7a1d67ca90b6aa563ec133b70fc91c445
parent 505383 6f3709b3878117466168c40affa7bca0b60cf75b
permissions -rw-r--r--
Bug 1553864 - Clean up some VS2015 PGO build config code r=nalexander This code was already dead during the VS2017 era (since that compiler changed to the `Hostx64\x86` path scheme), let alone clang-cl. Differential Revision: https://phabricator.services.mozilla.com/D33513

/* -*- 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