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 { 29 static const size_t value = _I0; 30 }; 31 32 template <size_t _I0, size_t _I1, size_t ..._In> 33 struct __static_max<_I0, _I1, _In...> 34 { 35 static const size_t value = _I0 >= _I1 ? __static_max<_I0, _In...>::value : 36 __static_max<_I1, _In...>::value; 37 }; 38 39 template <size_t _Len, class _Type0, class ..._Types> 40 struct aligned_union 41 { 42 static const size_t alignment_value = __static_max<_LIBCPP_PREFERRED_ALIGNOF(_Type0), 43 _LIBCPP_PREFERRED_ALIGNOF(_Types)...>::value; 44 static const size_t __len = __static_max<_Len, sizeof(_Type0), 45 sizeof(_Types)...>::value; 46 typedef typename aligned_storage<__len, alignment_value>::type type; 47 }; 48 49 #if _LIBCPP_STD_VER > 11 50 template <size_t _Len, class ..._Types> using aligned_union_t = typename aligned_union<_Len, _Types...>::type; 51 #endif 52 53 _LIBCPP_END_NAMESPACE_STD 54 55 #endif // _LIBCPP___TYPE_TRAITS_ALIGNED_UNION_H 56