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___COROUTINE_COROUTINE_TRAITS_H 10 #define _LIBCPP___COROUTINE_COROUTINE_TRAITS_H 11 12 #include <__config> 13 #include <type_traits> 14 15 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 16 # pragma GCC system_header 17 # pragma clang include_instead(<coroutine>) 18 #endif 19 20 #if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_CXX20_COROUTINES) 21 22 _LIBCPP_BEGIN_NAMESPACE_STD 23 24 // [coroutine.traits] 25 // [coroutine.traits.primary] 26 // The header <coroutine> defined the primary template coroutine_traits such that 27 // if ArgTypes is a parameter pack of types and if the qualified-id R::promise_type 28 // is valid and denotes a type ([temp.deduct]), then coroutine_traits<R, ArgTypes...> 29 // has the following publicly accessible memebr: 30 // 31 // using promise_type = typename R::promise_type; 32 // 33 // Otherwise, coroutine_traits<R, ArgTypes...> has no members. 34 template <class _Tp, class = void> 35 struct __coroutine_traits_sfinae {}; 36 37 template <class _Tp> 38 struct __coroutine_traits_sfinae< 39 _Tp, typename __void_t<typename _Tp::promise_type>::type> 40 { 41 using promise_type = typename _Tp::promise_type; 42 }; 43 44 template <class _Ret, class... _Args> 45 struct coroutine_traits 46 : public __coroutine_traits_sfinae<_Ret> 47 { 48 }; 49 50 _LIBCPP_END_NAMESPACE_STD 51 52 #endif // __LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_CXX20_COROUTINES) 53 54 #endif // _LIBCPP___COROUTINE_COROUTINE_TRAITS_H 55