85e62e6d13
Bug: None Change-Id: Iba1d66d9985f449c5d3710d7d615d4b25acf763b Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/196360 Reviewed-by: Per Kjellander <perkj@webrtc.org> Reviewed-by: Tommi <tommi@webrtc.org> Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org> Cr-Commit-Position: refs/heads/master@{#32772}
41 lines
1.7 KiB
C++
41 lines
1.7 KiB
C++
/*
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* Copyright (c) 2020 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef RTC_BASE_SYSTEM_NO_UNIQUE_ADDRESS_H_
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#define RTC_BASE_SYSTEM_NO_UNIQUE_ADDRESS_H_
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#include "rtc_base/sanitizer.h"
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// RTC_NO_UNIQUE_ADDRESS is a portable annotation to tell the compiler that
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// a data member need not have an address distinct from all other non-static
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// data members of its class.
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// It allows empty types to actually occupy zero bytes as class members,
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// instead of occupying at least one byte just so that they get their own
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// address. There is almost never any reason not to use it on class members
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// that could possibly be empty.
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// The macro expands to [[no_unique_address]] if the compiler supports the
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// attribute, it expands to nothing otherwise.
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// Clang should supports this attribute since C++11, while other compilers
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// should add support for it starting from C++20. Among clang compilers,
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// clang-cl doesn't support it yet and support is unclear also when the target
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// platform is iOS.
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//
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// TODO(bugs.webrtc.org/12218): Re-enable on MSan builds.
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#if !RTC_HAS_MSAN && \
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((defined(__clang__) && !defined(_MSC_VER) && !defined(WEBRTC_IOS)) || \
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__cplusplus > 201703L)
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// NOLINTNEXTLINE(whitespace/braces)
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#define RTC_NO_UNIQUE_ADDRESS [[no_unique_address]]
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#else
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#define RTC_NO_UNIQUE_ADDRESS
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#endif
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#endif // RTC_BASE_SYSTEM_NO_UNIQUE_ADDRESS_H_
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