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 #include <boost/atomic/detail/header.hpp> 20 21 #ifdef BOOST_HAS_PRAGMA_ONCE 22 #pragma once 23 #endif 24 25 // Detection logic is based on boost/core/addressof.hpp 26 #if defined(BOOST_MSVC_FULL_VER) && BOOST_MSVC_FULL_VER >= 190024215 27 #define BOOST_ATOMIC_DETAIL_HAS_BUILTIN_ADDRESSOF 28 #elif defined(BOOST_GCC) && BOOST_GCC >= 70000 29 #define BOOST_ATOMIC_DETAIL_HAS_BUILTIN_ADDRESSOF 30 #elif defined(__has_builtin) 31 #if __has_builtin(__builtin_addressof) 32 #define BOOST_ATOMIC_DETAIL_HAS_BUILTIN_ADDRESSOF 33 #endif 34 #endif 35 36 namespace boost { 37 namespace atomics { 38 namespace detail { 39 40 template< typename T > addressof(T & value)41BOOST_FORCEINLINE T* addressof(T& value) BOOST_NOEXCEPT 42 { 43 #if defined(BOOST_ATOMIC_DETAIL_HAS_BUILTIN_ADDRESSOF) 44 return __builtin_addressof(value); 45 #else 46 // Note: The point of using a local struct as the intermediate type instead of char is to avoid gcc warnings 47 // if T is a const volatile char*: 48 // warning: casting 'const volatile char* const' to 'const volatile char&' does not dereference pointer 49 // The local struct makes sure T is not related to the cast target type. 50 struct opaque_type; 51 return reinterpret_cast< T* >(&const_cast< opaque_type& >(reinterpret_cast< const volatile opaque_type& >(value))); 52 #endif 53 } 54 55 } // namespace detail 56 } // namespace atomics 57 } // namespace boost 58 59 #include <boost/atomic/detail/footer.hpp> 60 61 #endif // BOOST_ATOMIC_DETAIL_ADDRESSOF_HPP_INCLUDED_ 62