| /* |
| * Copyright (c) 2020 The WebRTC project authors. All Rights Reserved. |
| * |
| * Use of this source code is governed by a BSD-style license |
| * that can be found in the LICENSE file in the root of the source |
| * tree. An additional intellectual property rights grant can be found |
| * in the file PATENTS. All contributing project authors may |
| * be found in the AUTHORS file in the root of the source tree. |
| */ |
| |
| #ifndef RTC_BASE_SYSTEM_NO_UNIQUE_ADDRESS_H_ |
| #define RTC_BASE_SYSTEM_NO_UNIQUE_ADDRESS_H_ |
| |
| #include "rtc_base/sanitizer.h" |
| |
| // RTC_NO_UNIQUE_ADDRESS is a portable annotation to tell the compiler that |
| // a data member need not have an address distinct from all other non-static |
| // data members of its class. |
| // It allows empty types to actually occupy zero bytes as class members, |
| // instead of occupying at least one byte just so that they get their own |
| // address. There is almost never any reason not to use it on class members |
| // that could possibly be empty. |
| // The macro expands to [[no_unique_address]] if the compiler supports the |
| // attribute, it expands to nothing otherwise. |
| // Clang should supports this attribute since C++11, while other compilers |
| // should add support for it starting from C++20. Among clang compilers, |
| // clang-cl doesn't support it yet and support is unclear also when the target |
| // platform is iOS. |
| // |
| // TODO(bugs.webrtc.org/12218): Re-enable on MSan builds. |
| #if !RTC_HAS_MSAN && \ |
| ((defined(__clang__) && !defined(_MSC_VER) && !defined(WEBRTC_IOS)) || \ |
| __cplusplus > 201703L) |
| // NOLINTNEXTLINE(whitespace/braces) |
| #define RTC_NO_UNIQUE_ADDRESS [[no_unique_address]] |
| #else |
| #define RTC_NO_UNIQUE_ADDRESS |
| #endif |
| |
| #endif // RTC_BASE_SYSTEM_NO_UNIQUE_ADDRESS_H_ |
