From 4faca9e9e743c8b09e067eee389750bd375823db Mon Sep 17 00:00:00 2001
From: Beman <bdawes@acm.org>
Date: Sat, 30 Apr 2016 15:03:15 -0400
Subject: [PATCH] Add undocumented BOOST_MSVC_SFINAE_EXPR and
 BOOST_MSVC_CXX11_CONSTEXPR macros to ease testing of MSVC compiler updates

---
 include/boost/config/compiler/visualc.hpp | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/include/boost/config/compiler/visualc.hpp b/include/boost/config/compiler/visualc.hpp
index 888932a6..5d51d185 100644
--- a/include/boost/config/compiler/visualc.hpp
+++ b/include/boost/config/compiler/visualc.hpp
@@ -198,14 +198,22 @@
 // See also: http://www.boost.org/libs/utility/value_init.htm#compiler_issues
 // (Niels Dekker, LKEB, May 2010)
 #define BOOST_NO_COMPLETE_VALUE_INITIALIZATION
+//
 // C++11 features not supported by any versions
-#define BOOST_NO_SFINAE_EXPR
 #define BOOST_NO_TWO_PHASE_NAME_LOOKUP
 //
+// To ease testing MSVC compiler updates, suppress BOOST_NO_SFINAE_EXPR if requested
+#ifndef BOOST_MSVC_SFINAE_EXPR
+#define BOOST_NO_SFINAE_EXPR
+#endif
+//
 // This is somewhat supported in VC14, but we may need to wait for
 // a service release before enabling:
 //
+// To ease testing MSVC compiler updates, suppress BOOST_NO_CXX11_CONSTEXPR if requested
+#ifndef BOOST_MSVC_CXX11_CONSTEXPR
 #define BOOST_NO_CXX11_CONSTEXPR
+#endif
 
 // C++ 14:
 #if !defined(__cpp_aggregate_nsdmi) || (__cpp_aggregate_nsdmi < 201304)