Add new macro BOOST_NO_CXX17_HDR_OPTIONAL.

Fixes: https://github.com/boostorg/config/issues/236.
2018-08-04 19:21:21 +01:00
1 parent ec3318d47a
commit 5364a2e8a7
@@ -202,6 +202,7 @@
 #if (_MSC_VER < 1911) || (_MSVC_LANG < 201703)
 #  define BOOST_NO_CXX17_STRUCTURED_BINDINGS
 #  define BOOST_NO_CXX17_IF_CONSTEXPR
+#  define BOOST_NO_CXX17_HDR_OPTIONAL
 #endif

 // MSVC including version 14 has not yet completely