Add <optional> header.

This patch is largely thanks to Casey Carter @ Microsoft. He did the initial
work of porting our experimental implementation and tests over to namespace
std.

llvm-svn: 283977

1 files changed, 39 insertions, 0 deletions

diff --git a/libcxx/test/std/utilities/optional/optional.nullops/not_equal.pass.cpp b/libcxx/test/std/utilities/optional/optional.nullops/not_equal.pass.cpp
new file mode 100644
index 00000000000..1c96dd42e80
--- /dev/null
+++ b/libcxx/test/std/utilities/optional/optional.nullops/not_equal.pass.cpp
@@ -0,0 +1,39 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+// <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()
+{
+    using std::optional;
+    using std::nullopt_t;
+    using std::nullopt;
+
+    {
+    typedef int T;
+    typedef optional<T> O;
+
+    constexpr O o1;     // disengaged
+    constexpr O o2{1};  // engaged
+
+    static_assert ( !(nullopt != o1), "" );
+    static_assert (  (nullopt != o2), "" );
+    static_assert ( !(o1 != nullopt), "" );
+    static_assert (  (o2 != nullopt), "" );
+
+    static_assert (noexcept(nullopt != o1), "");
+    static_assert (noexcept(o1 != nullopt), "");
+    }
+}