Implement N3672, optional<T>.

llvm-svn: 189772
diff --git a/libcxx/test/utilities/optional/optional.nullops/eqaul.pass.cpp b/libcxx/test/utilities/optional/optional.nullops/eqaul.pass.cpp
new file mode 100644
index 0000000..bfc8e16
--- /dev/null
+++ b/libcxx/test/utilities/optional/optional.nullops/eqaul.pass.cpp
@@ -0,0 +1,37 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// template <class T> constexpr bool operator==(const optional<T>& x, nullopt_t) noexcept;
+// template <class T> constexpr bool operator==(nullopt_t, const optional<T>& x) noexcept;
+
+#include <optional>
+
+int main()
+{
+#if _LIBCPP_STD_VER > 11
+    {
+    typedef int T;
+    typedef std::optional<T> O;
+    
+    constexpr O o1;     // disengaged
+    constexpr O o2{1};  // engaged
+
+    static_assert (   std::nullopt == o1 , "" );
+    static_assert ( !(std::nullopt == o2), "" );
+    static_assert (   o1 == std::nullopt , "" );
+    static_assert ( !(o2 == std::nullopt), "" );
+
+    static_assert (noexcept(std::nullopt == o1), "");
+    static_assert (noexcept(o1 == std::nullopt), "");
+    }
+#endif
+}