From fb9957101f3076aca0e94c396ccf3ff1ee3f74d3 Mon Sep 17 00:00:00 2001
From: jzmaddock <john@johnmaddock.co.uk>
Date: Sat, 4 Aug 2018 19:35:11 +0100
Subject: [PATCH] Correct use of __has_include in suffix.hpp.

---
 include/boost/config/detail/suffix.hpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/boost/config/detail/suffix.hpp b/include/boost/config/detail/suffix.hpp
index d7c74aa4..1d6a9eac 100644
--- a/include/boost/config/detail/suffix.hpp
+++ b/include/boost/config/detail/suffix.hpp
@@ -1024,8 +1024,12 @@ namespace std{ using ::type_info; }
 #endif
 
 // This is a catch all case for obsolete compilers / std libs:
-#if !defined(__has_include) || !__has_include(<optional>)
+#if !defined(__has_include)
 #  define BOOST_NO_CXX17_HDR_OPTIONAL
+#else
+#if !__has_include(<optional>)
+#  define BOOST_NO_CXX17_HDR_OPTIONAL
+#endif
 #endif
 
 //