整理

include/boost/atomic/detail/addressof.hpp

@@ -0,0 +1,65 @@
+/*
+ * Distributed under the Boost Software License, Version 1.0.
+ * (See accompanying file LICENSE_1_0.txt or copy at
+ * http://www.boost.org/LICENSE_1_0.txt)
+ *
+ * Copyright (c) 2018, 2025 Andrey Semashev
+ */
+/*!
+ * \file   atomic/detail/addressof.hpp
+ *
+ * This header defines \c addressof helper function. It is similar to \c boost::addressof but it is more
+ * lightweight and also contains a workaround for some compiler warnings.
+ */
+
+#ifndef BOOST_ATOMIC_DETAIL_ADDRESSOF_HPP_INCLUDED_
+#define BOOST_ATOMIC_DETAIL_ADDRESSOF_HPP_INCLUDED_
+
+#include <boost/atomic/detail/config.hpp>
+#include <boost/atomic/detail/header.hpp>
+
+#ifdef BOOST_HAS_PRAGMA_ONCE
+#pragma once
+#endif
+
+// Detection logic is based on boost/core/addressof.hpp
+#if defined(BOOST_MSVC_FULL_VER) && BOOST_MSVC_FULL_VER >= 190024215
+#define BOOST_ATOMIC_DETAIL_HAS_BUILTIN_ADDRESSOF
+#elif defined(BOOST_GCC) && BOOST_GCC >= 70000
+#define BOOST_ATOMIC_DETAIL_HAS_BUILTIN_ADDRESSOF
+#elif defined(__has_builtin)
+#if __has_builtin(__builtin_addressof)
+#define BOOST_ATOMIC_DETAIL_HAS_BUILTIN_ADDRESSOF
+#endif
+#endif
+
+namespace boost {
+namespace atomics {
+namespace detail {
+
+template< typename T >
+BOOST_FORCEINLINE
+#if defined(BOOST_ATOMIC_DETAIL_HAS_BUILTIN_ADDRESSOF)
+constexpr
+#endif
+T* addressof(T& value) noexcept
+{
+#if defined(BOOST_ATOMIC_DETAIL_HAS_BUILTIN_ADDRESSOF)
+    return __builtin_addressof(value);
+#else
+    // Note: The point of using a local struct as the intermediate type instead of char is to avoid gcc warnings
+    // if T is a const volatile char*:
+    // warning: casting 'const volatile char* const' to 'const volatile char&' does not dereference pointer
+    // The local struct makes sure T is not related to the cast target type.
+    struct opaque_type;
+    return reinterpret_cast< T* >(&const_cast< opaque_type& >(reinterpret_cast< const volatile opaque_type& >(value)));
+#endif
+}
+
+} // namespace detail
+} // namespace atomics
+} // namespace boost
+
+#include <boost/atomic/detail/footer.hpp>
+
+#endif // BOOST_ATOMIC_DETAIL_ADDRESSOF_HPP_INCLUDED_