[libcxx] Add <experimental/chrono>

Summary:
This patch adds <experimental/chrono> which only contains a single variable template.

See: https://rawgit.com/cplusplus/fundamentals-ts/v1/fundamentals-ts.html#time

Reviewers: jroelofs, danalbert, K-ballo, mclow.lists

Reviewed By: mclow.lists

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D7352

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@227860 91177308-0d34-0410-b5e6-96231b3b80d8

test/libcxx/experimental/utilities/time/header.chrono.synop/includes.pass.cpp

@@ -0,0 +1,22 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// <experimental/chrono>
+
+#include <experimental/chrono>
+
+#if _LIBCPP_STD_VER > 11
+# ifndef _LIBCPP_CHRONO
+#   error "<experimental/chrono> must include <chrono>"
+# endif
+#endif
+
+int main()
+{
+}

test/libcxx/experimental/utilities/time/version.pass.cpp

@@ -0,0 +1,20 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// <experimental/chrono>
+
+#include <experimental/chrono>
+
+#ifndef _LIBCPP_VERSION
+#error _LIBCPP_VERSION not defined
+#endif
+
+int main()
+{
+}

test/std/experimental/utilities/time/header.chrono.synop/includes.pass.cpp

@@ -0,0 +1,19 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// <experimental/chrono>
+
+#include <experimental/chrono>
+
+int main()
+{
+  // Check that <chrono> has been included.
+  std::chrono::seconds s;
+  ((void)s);
+}

test/std/experimental/utilities/time/header.chrono.synop/treat_as_floating_point_v.pass.cpp

@@ -0,0 +1,49 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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
+
+// <experimental/chrono>
+
+// template <class Rep> constexpr bool treat_as_floating_point_v;
+
+#include <experimental/chrono>
+#include <type_traits>
+
+namespace ex = std::chrono::experimental;
+namespace cr = std::chrono;
+
+template <class T, bool Expect>
+void test()
+{
+  static_assert(
+    ex::treat_as_floating_point_v<T> == Expect, ""
+  );
+  static_assert(
+    ex::treat_as_floating_point_v<T> == cr::treat_as_floating_point<T>::value, ""
+  );
+}
+
+int main()
+{
+  {
+    static_assert(
+      std::is_same<
+        decltype(ex::treat_as_floating_point_v<float>), const bool
+      >::value, ""
+    );
+  }
+  test<int, false>();
+  test<unsigned, false>();
+  test<char, false>();
+  test<bool, false>();
+  test<float, true>();
+  test<double, true>();
+  test<long double, true>();
+}