From 626a6243e3882498f5af4cd53a7aa92c3346864a Mon Sep 17 00:00:00 2001
From: Oblivion <ehsan.sadroid@gmail.com>
Date: Wed, 15 Dec 2021 21:18:05 +0000
Subject: [PATCH] C++20 not Building with VS2019

---
 .../opentelemetry/nostd/absl/meta/type_traits.h | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/api/include/opentelemetry/nostd/absl/meta/type_traits.h b/api/include/opentelemetry/nostd/absl/meta/type_traits.h
index fc69bb5d66..74ae82a6b6 100644
--- a/api/include/opentelemetry/nostd/absl/meta/type_traits.h
+++ b/api/include/opentelemetry/nostd/absl/meta/type_traits.h
@@ -616,8 +616,21 @@ using common_type_t = typename std::common_type<T...>::type;
 template <typename T>
 using underlying_type_t = typename std::underlying_type<T>::type;
 
-template <typename T>
-using result_of_t = typename std::result_of<T>::type;
+namespace type_traits_internal {
+
+#if __cplusplus >= 201703L
+// std::result_of is deprecated (C++17) or removed (C++20)
+template<typename> struct result_of;
+template<typename F, typename... Args>
+struct result_of<F(Args...)> : std::invoke_result<F, Args...> {};
+#else
+template<typename F> using result_of = std::result_of<F>;
+#endif
+
+}  // namespace type_traits_internal
+
+template<typename F>
+using result_of_t = typename type_traits_internal::result_of<F>::type;
 
 namespace type_traits_internal {
 // In MSVC we can't probe std::hash or stdext::hash because it triggers a