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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-exception6//7//===----------------------------------------------------------------------===//8 9#ifndef _LIBCPP___COROUTINE_COROUTINE_TRAITS_H10#define _LIBCPP___COROUTINE_COROUTINE_TRAITS_H11 12#include <__config>13#include <__type_traits/void_t.h>14 15#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)16# pragma GCC system_header17#endif18 19#if _LIBCPP_STD_VER >= 2020 21_LIBCPP_BEGIN_NAMESPACE_STD22 23// [coroutine.traits]24// [coroutine.traits.primary]25// The header <coroutine> defined the primary template coroutine_traits such that26// if ArgTypes is a parameter pack of types and if the qualified-id R::promise_type27// is valid and denotes a type ([temp.deduct]), then coroutine_traits<R, ArgTypes...>28// has the following publicly accessible memebr:29//30// using promise_type = typename R::promise_type;31//32// Otherwise, coroutine_traits<R, ArgTypes...> has no members.33template <class _Tp, class = void>34struct __coroutine_traits_sfinae {};35 36template <class _Tp>37struct __coroutine_traits_sfinae< _Tp, __void_t<typename _Tp::promise_type> > {38 using promise_type = typename _Tp::promise_type;39};40 41template <class _Ret, class... _Args>42struct coroutine_traits : public __coroutine_traits_sfinae<_Ret> {};43 44_LIBCPP_END_NAMESPACE_STD45 46#endif // _LIBCPP_STD_VER >= 2047 48#endif // _LIBCPP___COROUTINE_COROUTINE_TRAITS_H49