From 619aa50a73dfb86c19ba3cd34342628bc7bf71eb Mon Sep 17 00:00:00 2001
From: "claude[bot]" <41898282+claude[bot]@users.noreply.github.com>
Date: Thu, 4 Dec 2025 08:46:55 +0000
Subject: [PATCH] Use <utility> instead of <functional> for
 std::reference_wrapper on C++20+

For C++20 and later, std::reference_wrapper is available in <utility>,
which is a lighter-weight header than <functional>.

Fixes #210

Co-authored-by: Vinnie Falco <vinniefalco@users.noreply.github.com>
---
 include/boost/http_proto/detail/type_traits.hpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/boost/http_proto/detail/type_traits.hpp b/include/boost/http_proto/detail/type_traits.hpp
index 457e5ea2..bb3c3eb1 100644
--- a/include/boost/http_proto/detail/type_traits.hpp
+++ b/include/boost/http_proto/detail/type_traits.hpp
@@ -10,7 +10,11 @@
 #ifndef BOOST_HTTP_PROTO_DETAIL_TYPE_TRAITS_HPP
 #define BOOST_HTTP_PROTO_DETAIL_TYPE_TRAITS_HPP
 
+#if __cplusplus >= 202002L
+#include <utility>
+#else
 #include <functional>
+#endif
 #include <type_traits>
 
 namespace boost {