Implement N3672, optional<T>.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@189772 91177308-0d34-0410-b5e6-96231b3b80d8

test/utilities/optional/optional.object/optional_const_void.fail.cpp

@@ -0,0 +1,23 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <optional>
+
+// T shall be an object type and shall satisfy the requirements of Destructible
+
+#include <optional>
+
+int main()
+{
+#if _LIBCPP_STD_VER > 11
+    std::optional<const void> opt;
+#else
+#error
+#endif  // _LIBCPP_STD_VER > 11
+}