Merge pull request #271 from boostorg/variant

Add BOOST_NO_CXX17_HDR_VARIANT.

include/boost/config/detail/suffix.hpp

@@ -1027,6 +1027,7 @@ namespace std{ using ::type_info; }
 #if !defined(__has_include)
 #  define BOOST_NO_CXX17_HDR_OPTIONAL
 #  define BOOST_NO_CXX17_HDR_STRING_VIEW
+#  define BOOST_NO_CXX17_HDR_VARIANT
 #else
 #if !__has_include(<optional>)
 #  define BOOST_NO_CXX17_HDR_OPTIONAL
@@ -1034,6 +1035,9 @@ namespace std{ using ::type_info; }
 #if !__has_include(<string_view>)
 #  define BOOST_NO_CXX17_HDR_STRING_VIEW
 #endif
+#if !__has_include(<variant>)
+#  define BOOST_NO_CXX17_HDR_VARIANT
+#endif
 #endif
 
 //

include/boost/config/stdlib/dinkumware.hpp

@@ -176,6 +176,7 @@
 #  define BOOST_NO_CXX17_ITERATOR_TRAITS
 #  define BOOST_NO_CXX17_HDR_STRING_VIEW
 #  define BOOST_NO_CXX17_HDR_OPTIONAL
+#  define BOOST_NO_CXX17_HDR_VARIANT
 #endif
 #if !defined(_CPPLIB_VER) || (_CPPLIB_VER < 650) || !defined(_HAS_CXX17) || (_HAS_CXX17 == 0) || !defined(_MSVC_STL_UPDATE) || (_MSVC_STL_UPDATE < 201709)
 #  define BOOST_NO_CXX17_STD_INVOKE

include/boost/config/stdlib/libcpp.hpp

@@ -91,6 +91,7 @@
 #  define BOOST_NO_CXX17_STD_APPLY
 #  define BOOST_NO_CXX17_HDR_OPTIONAL
 #  define BOOST_NO_CXX17_HDR_STRING_VIEW
+#  define BOOST_NO_CXX17_HDR_VARIANT
 #endif
 #if (_LIBCPP_VERSION > 4000) && (__cplusplus > 201402L) && !defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
 #  define BOOST_NO_AUTO_PTR

include/boost/config/stdlib/libstdcpp3.hpp

@@ -301,6 +301,7 @@ extern "C" char *gets (char *__s);
 #  define BOOST_NO_CXX17_STD_APPLY
 #  define BOOST_NO_CXX17_HDR_OPTIONAL
 #  define BOOST_NO_CXX17_HDR_STRING_VIEW
+#  define BOOST_NO_CXX17_HDR_VARIANT
 #endif
 
 #if defined(__has_include)