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, 48 insertions, 0 deletions

diff --git a/libcxx/test/std/utilities/optional/optional.hash/hash.pass.cpp b/libcxx/test/std/utilities/optional/optional.hash/hash.pass.cpp
new file mode 100644
index 00000000000..dfdd07ddf45
--- /dev/null
+++ b/libcxx/test/std/utilities/optional/optional.hash/hash.pass.cpp
@@ -0,0 +1,48 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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> struct hash<optional<T>>;
+
+#include <optional>
+#include <string>
+#include <memory>
+#include <cassert>
+
+
+int main()
+{
+    using std::optional;
+    const std::size_t nullopt_hash =
+        std::hash<optional<double>>{}(optional<double>{});
+
+    {
+        typedef int T;
+        optional<T> opt;
+        assert(std::hash<optional<T>>{}(opt) == nullopt_hash);
+        opt = 2;
+        assert(std::hash<optional<T>>{}(opt) == std::hash<T>{}(*opt));
+    }
+    {
+        typedef std::string T;
+        optional<T> opt;
+        assert(std::hash<optional<T>>{}(opt) == nullopt_hash);
+        opt = std::string("123");
+        assert(std::hash<optional<T>>{}(opt) == std::hash<T>{}(*opt));
+    }
+    {
+        typedef std::unique_ptr<int> T;
+        optional<T> opt;
+        assert(std::hash<optional<T>>{}(opt) == nullopt_hash);
+        opt = std::unique_ptr<int>(new int(3));
+        assert(std::hash<optional<T>>{}(opt) == std::hash<T>{}(*opt));
+    }
+}