From 78f26da1f3a5a3831e9e70efe83f9c56eef94e8c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ion=20Gazta=C3=B1aga?= <igaztanaga@gmail.com>
Date: Tue, 4 Jan 2022 16:27:43 +0100
Subject: [PATCH] Forward declare std::contiguous_iterator_tag only when the
 standard library defines it

---
 include/boost/move/detail/iterator_traits.hpp | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/include/boost/move/detail/iterator_traits.hpp b/include/boost/move/detail/iterator_traits.hpp
index d31a72c..640fbff 100644
--- a/include/boost/move/detail/iterator_traits.hpp
+++ b/include/boost/move/detail/iterator_traits.hpp
@@ -33,8 +33,17 @@ struct forward_iterator_tag;
 struct bidirectional_iterator_tag;
 struct random_access_iterator_tag;
 struct output_iterator_tag;
+
+#if (  (defined(BOOST_GNU_STDLIB) && (__cplusplus > 201703L))\
+    || (defined(_LIBCPP_VERSION) && (_LIBCPP_STD_VER > 17))\
+    || (defined(_YVALS) && defined(_CPPLIB_VER) && defined(__cpp_lib_concepts))\
+    || (__cplusplus >= 202002L)\
+    )
+#  define BOOST_MOVE_CONTIGUOUS_ITERATOR_TAG
 struct contiguous_iterator_tag;
 
+#endif
+
 BOOST_MOVE_STD_NS_END
 #include <boost/move/detail/std_ns_end.hpp>