1 /* 2 * Distributed under the Boost Software License, Version 1.0. 3 * (See accompanying file LICENSE_1_0.txt or copy at 4 * http://www.boost.org/LICENSE_1_0.txt) 5 * 6 * Copyright (c) 2018 Andrey Semashev 7 */ 8 /*! 9 * \file atomic/detail/addressof.hpp 10 * 11 * This header defines \c addressof helper function. It is similar to \c boost::addressof but it is more 12 * lightweight and also contains a workaround for some compiler warnings. 13 */ 14 15 #ifndef BOOST_ATOMIC_DETAIL_ADDRESSOF_HPP_INCLUDED_ 16 #define BOOST_ATOMIC_DETAIL_ADDRESSOF_HPP_INCLUDED_ 17 18 #include <boost/atomic/detail/config.hpp> 19 20 #ifdef BOOST_HAS_PRAGMA_ONCE 21 #pragma once 22 #endif 23 24 // Detection logic is based on boost/core/addressof.hpp 25 #if defined(BOOST_MSVC_FULL_VER) && BOOST_MSVC_FULL_VER >= 190024215 26 #define BOOST_ATOMIC_DETAIL_HAS_BUILTIN_ADDRESSOF 27 #elif defined(BOOST_GCC) && BOOST_GCC >= 70000 28 #define BOOST_ATOMIC_DETAIL_HAS_BUILTIN_ADDRESSOF 29 #elif defined(__has_builtin) 30 #if __has_builtin(__builtin_addressof) 31 #define BOOST_ATOMIC_DETAIL_HAS_BUILTIN_ADDRESSOF 32 #endif 33 #endif 34 35 namespace boost { 36 namespace atomics { 37 namespace detail { 38 39 template< typename T > addressof(T & value)40BOOST_FORCEINLINE T* addressof(T& value) BOOST_NOEXCEPT 41 { 42 #if defined(BOOST_ATOMIC_DETAIL_HAS_BUILTIN_ADDRESSOF) 43 return __builtin_addressof(value); 44 #else 45 // Note: The point of using a local struct as the intermediate type instead of char is to avoid gcc warnings 46 // if T is a const volatile char*: 47 // warning: casting 'const volatile char* const' to 'const volatile char&' does not dereference pointer 48 // The local struct makes sure T is not related to the cast target type. 49 struct opaque_type; 50 return reinterpret_cast< T* >(&const_cast< opaque_type& >(reinterpret_cast< const volatile opaque_type& >(value))); 51 #endif 52 } 53 54 } // namespace detail 55 } // namespace atomics 56 } // namespace boost 57 58 #endif // BOOST_ATOMIC_DETAIL_ADDRESSOF_HPP_INCLUDED_ 59