af267993a7
1013fe3c0cfd7582e94ef2d4bfd79da7ea1a1289 used to implement LWG2770, but cb0d4df97490ec2d2b1cdf7574d26b1bc4063599 made LWG2770 unimplemented again because of CWG2386. This patch re-implements LWG2770, while keeping the libc++-specific implementation strategy (which is controversial as noted in LWG4040). Drive-by: - Make the test coverage for the controversial part noted in LWG4040 libc++-only. - Add the previously missed entry for LWG2770 to the documentation.
75 lines
2.5 KiB
C++
75 lines
2.5 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___TUPLE_TUPLE_SIZE_H
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#define _LIBCPP___TUPLE_TUPLE_SIZE_H
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#include <__config>
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#include <__cstddef/size_t.h>
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#include <__fwd/tuple.h>
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#include <__tuple/tuple_types.h>
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#include <__type_traits/enable_if.h>
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#include <__type_traits/integral_constant.h>
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#include <__type_traits/is_const.h>
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#include <__type_traits/is_volatile.h>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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_LIBCPP_BEGIN_NAMESPACE_STD
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template <class _Tp>
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struct _LIBCPP_TEMPLATE_VIS tuple_size;
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#if !defined(_LIBCPP_CXX03_LANG)
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template <class _Tp, class...>
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using __enable_if_tuple_size_imp _LIBCPP_NODEBUG = _Tp;
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template <class _Tp>
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struct _LIBCPP_TEMPLATE_VIS tuple_size<
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__enable_if_tuple_size_imp<const _Tp, __enable_if_t<!is_volatile<_Tp>::value>, decltype(tuple_size<_Tp>::value)>>
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: public integral_constant<size_t, tuple_size<_Tp>::value> {};
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template <class _Tp>
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struct _LIBCPP_TEMPLATE_VIS tuple_size<
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__enable_if_tuple_size_imp<volatile _Tp, __enable_if_t<!is_const<_Tp>::value>, decltype(tuple_size<_Tp>::value)>>
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: public integral_constant<size_t, tuple_size<_Tp>::value> {};
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template <class _Tp>
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struct _LIBCPP_TEMPLATE_VIS tuple_size<__enable_if_tuple_size_imp<const volatile _Tp, decltype(tuple_size<_Tp>::value)>>
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: public integral_constant<size_t, tuple_size<_Tp>::value> {};
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#else
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template <class _Tp>
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struct _LIBCPP_TEMPLATE_VIS tuple_size<const _Tp> : public tuple_size<_Tp> {};
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template <class _Tp>
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struct _LIBCPP_TEMPLATE_VIS tuple_size<volatile _Tp> : public tuple_size<_Tp> {};
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template <class _Tp>
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struct _LIBCPP_TEMPLATE_VIS tuple_size<const volatile _Tp> : public tuple_size<_Tp> {};
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#endif
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#ifndef _LIBCPP_CXX03_LANG
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template <class... _Tp>
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struct _LIBCPP_TEMPLATE_VIS tuple_size<tuple<_Tp...> > : public integral_constant<size_t, sizeof...(_Tp)> {};
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template <class... _Tp>
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struct _LIBCPP_TEMPLATE_VIS tuple_size<__tuple_types<_Tp...> > : public integral_constant<size_t, sizeof...(_Tp)> {};
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# if _LIBCPP_STD_VER >= 17
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template <class _Tp>
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inline constexpr size_t tuple_size_v = tuple_size<_Tp>::value;
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# endif
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#endif // _LIBCPP_CXX03_LANG
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___TUPLE_TUPLE_SIZE_H
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