From a05e4b8854673d719819f30ab882b15ae0debd1e Mon Sep 17 00:00:00 2001
From: Keyue Hu <hukeyue@vip.163.com>
Date: Sun, 29 Mar 2026 10:29:17 +0800
Subject: [PATCH] msvc: fix broken build against sdk7.1a

In SDKs older than 10.0 such as 7.1a, there is no header file named
synchapi.h. windows.h should be fine.

```
  In file included from D:\a\yass\yass\third_party\asio\include\asio/detail/mutex.hpp:23:
  D:\a\yass\yass\third_party\asio\include\asio/detail/win_mutex.hpp(25,10): fatal error: 'synchapi.h' file not found
     25 | #include <synchapi.h>
        |          ^~~~~~~~~~~~
  Note: including file:        D:\a\yass\yass\third_party\asio\include\asio/detail/push_options.hpp
```
---
 include/asio/detail/win_mutex.hpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/asio/detail/win_mutex.hpp b/include/asio/detail/win_mutex.hpp
index 015d1dbfbe..a11eb045ad 100644
--- a/include/asio/detail/win_mutex.hpp
+++ b/include/asio/detail/win_mutex.hpp
@@ -22,7 +22,9 @@
 #include "asio/detail/noncopyable.hpp"
 #include "asio/detail/scoped_lock.hpp"
 #include "asio/detail/socket_types.hpp"
+#ifndef _USING_V110_SDK71_
 #include <synchapi.h>
+#endif
 
 #include "asio/detail/push_options.hpp"