From a57c5683243ceacc58ee5e3bdc806f189df44dac Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@gmail.com>
Date: Mon, 4 Sep 2023 16:28:34 +0300
Subject: [PATCH] Do not use <shared_mutex> when BOOST_USE_WINAPI_VERSION is
 0x5xx (Windows XP). Fixes #113.

---
 include/boost/system/detail/mutex.hpp | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/include/boost/system/detail/mutex.hpp b/include/boost/system/detail/mutex.hpp
index c27e08a..8b43b9e 100644
--- a/include/boost/system/detail/mutex.hpp
+++ b/include/boost/system/detail/mutex.hpp
@@ -40,13 +40,20 @@ struct mutex
 // issues. However, shared_mutex is based on SRWLock and its
 // default constructor is constexpr, so we use that instead.
 
+#include <boost/winapi/config.hpp>
+
+// SRWLOCK is not available when targeting Windows XP
+#if BOOST_USE_WINAPI_VERSION >= BOOST_WINAPI_VERSION_WIN6
+
 #include <shared_mutex>
 
 #if BOOST_MSSTL_VERSION >= 142 || _HAS_SHARED_MUTEX
 # define BOOST_SYSTEM_HAS_MSSTL_SHARED_MUTEX
 #endif
 
-#endif
+#endif // BOOST_MSSTL_VERSION >= 142 || _HAS_SHARED_MUTEX
+
+#endif // BOOST_USE_WINAPI_VERSION >= BOOST_WINAPI_VERSION_WIN6
 
 #if defined(BOOST_SYSTEM_HAS_MSSTL_SHARED_MUTEX)