1 //===----------------------------------------------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef _LIBCPP___TYPE_TRAITS_ALIGNED_UNION_H 10 #define _LIBCPP___TYPE_TRAITS_ALIGNED_UNION_H 11 12 #include <__config> 13 #include <__type_traits/aligned_storage.h> 14 #include <__type_traits/integral_constant.h> 15 #include <cstddef> 16 17 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 18 # pragma GCC system_header 19 #endif 20 21 _LIBCPP_BEGIN_NAMESPACE_STD 22 23 template <size_t _I0, size_t... _In> 24 struct __static_max; 25 26 template <size_t _I0> 27 struct __static_max<_I0> { 28 static const size_t value = _I0; 29 }; 30 31 template <size_t _I0, size_t _I1, size_t... _In> 32 struct __static_max<_I0, _I1, _In...> { 33 static const size_t value = _I0 >= _I1 ? __static_max<_I0, _In...>::value : __static_max<_I1, _In...>::value; 34 }; 35 36 template <size_t _Len, class _Type0, class... _Types> 37 struct _LIBCPP_DEPRECATED_IN_CXX23 aligned_union { 38 static const size_t alignment_value = 39 __static_max<_LIBCPP_PREFERRED_ALIGNOF(_Type0), _LIBCPP_PREFERRED_ALIGNOF(_Types)...>::value; 40 static const size_t __len = __static_max<_Len, sizeof(_Type0), sizeof(_Types)...>::value; 41 typedef typename aligned_storage<__len, alignment_value>::type type; 42 }; 43 44 #if _LIBCPP_STD_VER >= 14 45 template <size_t _Len, class... _Types> 46 using aligned_union_t _LIBCPP_DEPRECATED_IN_CXX23 = typename aligned_union<_Len, _Types...>::type; 47 #endif 48 49 _LIBCPP_END_NAMESPACE_STD 50 51 #endif // _LIBCPP___TYPE_TRAITS_ALIGNED_UNION_H 52