From e4adc769aa7b952f2719cee0958222bc80e1ce81 Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@gmail.com>
Date: Thu, 4 Jan 2024 04:07:34 +0200
Subject: [PATCH] Disable use of std::launder under msvc-14.1. Fixes #160.

---
 include/boost/core/launder.hpp | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/include/boost/core/launder.hpp b/include/boost/core/launder.hpp
index 850338e..9ec5e7e 100644
--- a/include/boost/core/launder.hpp
+++ b/include/boost/core/launder.hpp
@@ -11,14 +11,28 @@
 //  Distributed under the Boost Software License, Version 1.0.
 //  https://www.boost.org/LICENSE_1_0.txt
 
+#include <boost/config.hpp>
+
 #if defined(__has_builtin)
 # if __has_builtin(__builtin_launder)
 #  define BOOST_CORE_HAS_BUILTIN_LAUNDER
 # endif
 #endif
 
-#if (__cplusplus >= 201703L || (defined(_MSVC_LANG) && _MSVC_LANG >= 201703L)) && !defined(BOOST_CORE_HAS_BUILTIN_LAUNDER)
-# include <new>
+#if defined(BOOST_MSVC) && BOOST_MSVC < 1920
+
+// msvc-14.1 suffers from internal compiler errors when using std::launder
+// https://github.com/boostorg/core/issues/160
+// https://github.com/boostorg/optional/issues/122
+
+#elif (BOOST_CXX_VERSION >= 201703L) && !defined(BOOST_CORE_HAS_BUILTIN_LAUNDER)
+
+#include <new>
+
+#if defined(__cpp_lib_launder)
+# define BOOST_CORE_HAS_STD_LAUNDER
+#endif
+
 #endif
 
 namespace boost
@@ -33,7 +47,7 @@ template<class T> T* launder( T* p )
     return __builtin_launder( p );
 }
 
-#elif (__cplusplus >= 201703L || (defined(_MSVC_LANG) && _MSVC_LANG >= 201703L)) && defined(__cpp_lib_launder)
+#elif defined(BOOST_CORE_HAS_STD_LAUNDER)
 
 template<class T> T* launder( T* p )
 {