From 32dbf1b99290ced5666f6b1e8390571c02c94c5e Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@gmail.com>
Date: Sun, 30 Apr 2023 18:44:56 +0300
Subject: [PATCH] Disable use of <shared_mutex> under the XP toolsets (v140_xp
 and v141_xp). Fixes #110.

---
 include/boost/system/detail/mutex.hpp | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/include/boost/system/detail/mutex.hpp b/include/boost/system/detail/mutex.hpp
index 4c2b0fa..c27e08a 100644
--- a/include/boost/system/detail/mutex.hpp
+++ b/include/boost/system/detail/mutex.hpp
@@ -31,7 +31,9 @@ struct mutex
 } // namespace system
 } // namespace boost
 
-#elif defined(BOOST_MSSTL_VERSION) && BOOST_MSSTL_VERSION >= 140
+#else // defined(BOOST_SYSTEM_DISABLE_THREADS)
+
+#if defined(BOOST_MSSTL_VERSION) && BOOST_MSSTL_VERSION >= 140
 
 // Under the MS STL, std::mutex::mutex() is not constexpr, as is
 // required by the standard, which leads to initialization order
@@ -40,6 +42,14 @@ struct mutex
 
 #include <shared_mutex>
 
+#if BOOST_MSSTL_VERSION >= 142 || _HAS_SHARED_MUTEX
+# define BOOST_SYSTEM_HAS_MSSTL_SHARED_MUTEX
+#endif
+
+#endif
+
+#if defined(BOOST_SYSTEM_HAS_MSSTL_SHARED_MUTEX)
+
 namespace boost
 {
 namespace system
@@ -53,7 +63,7 @@ typedef std::shared_mutex mutex;
 } // namespace system
 } // namespace boost
 
-#else
+#else // defined(BOOST_SYSTEM_HAS_MSSTL_SHARED_MUTEX)
 
 #include <mutex>
 
@@ -70,7 +80,8 @@ using std::mutex;
 } // namespace system
 } // namespace boost
 
-#endif
+#endif // defined(BOOST_SYSTEM_HAS_MSSTL_SHARED_MUTEX)
+#endif // defined(BOOST_SYSTEM_DISABLE_THREADS)
 
 namespace boost
 {