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, 61 insertions, 0 deletions

diff --git a/libcxx/test/std/utilities/optional/optional.object/optional.object.mod/reset.pass.cpp b/libcxx/test/std/utilities/optional/optional.object/optional.object.mod/reset.pass.cpp
new file mode 100644
index 00000000000..cee73da849b
--- /dev/null
+++ b/libcxx/test/std/utilities/optional/optional.object/optional.object.mod/reset.pass.cpp
@@ -0,0 +1,61 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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>
+
+// void reset() noexcept;
+
+#include <optional>
+#include <type_traits>
+#include <cassert>
+
+using std::optional;
+
+struct X
+{
+    static bool dtor_called;
+    ~X() {dtor_called = true;}
+};
+
+bool X::dtor_called = false;
+
+int main()
+{
+    {
+        optional<int> opt;
+        static_assert(noexcept(opt.reset()) == true, "");
+        opt.reset();
+        assert(static_cast<bool>(opt) == false);
+    }
+    {
+        optional<int> opt(3);
+        opt.reset();
+        assert(static_cast<bool>(opt) == false);
+    }
+    {
+        optional<X> opt;
+        static_assert(noexcept(opt.reset()) == true, "");
+        assert(X::dtor_called == false);
+        opt.reset();
+        assert(X::dtor_called == false);
+        assert(static_cast<bool>(opt) == false);
+    }
+    assert(X::dtor_called == false); // TRANSITION, Clang/C2 VSO#239997
+    {
+        optional<X> opt(X{});
+        X::dtor_called = false;
+        opt.reset();
+        assert(X::dtor_called == true);
+        assert(static_cast<bool>(opt) == false);
+        X::dtor_called = false;
+    }
+    assert(X::dtor_called == false); // TRANSITION, Clang/C2 VSO#239997
+}