From a6404a8fb25d007baec912df3917b177e388fe3c Mon Sep 17 00:00:00 2001
From: Edward Diener <eldlistmailingz@tropicsoft.com>
Date: Tue, 12 Nov 2019 14:57:09 -0500
Subject: [PATCH] Fixed __VA_OPT__ functionality for vc++ in c20 mode.

---
 include/boost/preprocessor/variadic/detail/has_opt.hpp | 9 +++++++++
 include/boost/preprocessor/variadic/has_opt.hpp        | 2 +-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/include/boost/preprocessor/variadic/detail/has_opt.hpp b/include/boost/preprocessor/variadic/detail/has_opt.hpp
index 11b6552..79edf3b 100644
--- a/include/boost/preprocessor/variadic/detail/has_opt.hpp
+++ b/include/boost/preprocessor/variadic/detail/has_opt.hpp
@@ -16,12 +16,21 @@
 #
 # if BOOST_PP_VARIADICS && defined(__cplusplus) && __cplusplus > 201703L
 #
+# if BOOST_PP_VARIADICS_MSVC
+# include <boost/preprocessor/cat.hpp>
+# endif
+#
 # define BOOST_PP_VARIADIC_HAS_OPT_FUNCTION(...) \
     __VA_OPT__(,) , 1, 0 \
 /**/
 #
+# if BOOST_PP_VARIADICS_MSVC
+# define BOOST_PP_VARIADIC_HAS_OPT_ELEM0(e0, ...) BOOST_PP_CAT(BOOST_PP_VARIADIC_HAS_OPT_ELEM_0(e0,__VA_ARGS__),)
+# define BOOST_PP_VARIADIC_HAS_OPT_ELEM2(e0, ...) BOOST_PP_CAT(BOOST_PP_VARIADIC_HAS_OPT_ELEM_2(e0,__VA_ARGS__),)
+# else
 # define BOOST_PP_VARIADIC_HAS_OPT_ELEM0(e0, ...) BOOST_PP_VARIADIC_HAS_OPT_ELEM_0(e0,__VA_ARGS__)
 # define BOOST_PP_VARIADIC_HAS_OPT_ELEM2(e0, ...) BOOST_PP_VARIADIC_HAS_OPT_ELEM_2(e0,__VA_ARGS__)
+# endif
 # define BOOST_PP_VARIADIC_HAS_OPT_ELEM_0(e0, ...) e0
 # define BOOST_PP_VARIADIC_HAS_OPT_ELEM_2(e0, e1, e2, ...) e2
 #
diff --git a/include/boost/preprocessor/variadic/has_opt.hpp b/include/boost/preprocessor/variadic/has_opt.hpp
index 4e5035e..3ab0890 100644
--- a/include/boost/preprocessor/variadic/has_opt.hpp
+++ b/include/boost/preprocessor/variadic/has_opt.hpp
@@ -16,7 +16,7 @@
 #
 # /* BOOST_PP_VARIADIC_HAS_OPT */
 #
-# if BOOST_PP_VARIADICS && defined(__cplusplus) && __cplusplus > 201703L && !BOOST_PP_VARIADICS_MSVC
+# if BOOST_PP_VARIADICS && defined(__cplusplus) && __cplusplus > 201703L
 # include <boost/preprocessor/variadic/detail/has_opt.hpp>
 # define BOOST_PP_VARIADIC_HAS_OPT() \
   BOOST_PP_VARIADIC_HAS_OPT_ELEM2(BOOST_PP_VARIADIC_HAS_OPT_FUNCTION(?),) \