1 files changed, 59 insertions, 0 deletions
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/plus.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/plus.pass.cpp
new file mode 100644
index 00000000000..fb8f536127e
--- /dev/null
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/plus.pass.cpp
@@ -0,0 +1,59 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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++03, c++11, c++14, c++17
+
+// <chrono>
+// class day;
+
+// constexpr day operator+(const day& x, const days& y) noexcept;
+//   Returns: day(unsigned{x} + y.count()).
+//
+// constexpr day operator+(const days& x, const day& y) noexcept;
+//   Returns: y + x.
+
+
+#include <chrono>
+#include <type_traits>
+#include <cassert>
+
+#include "test_macros.h"
+
+template <typename D, typename Ds>
+constexpr bool testConstexpr()
+{
+    D d{1};
+    Ds offset{23};
+    if (d + offset != D{24}) return false;
+    if (offset + d != D{24}) return false;
+    return true;
+}
+
+int main()
+{
+    using day  = std::chrono::day;
+    using days = std::chrono::days;
+
+    ASSERT_NOEXCEPT(std::declval<day>() + std::declval<days>());
+    ASSERT_NOEXCEPT(std::declval<days>() + std::declval<day>());
+
+    ASSERT_SAME_TYPE(day, decltype(std::declval<day>() + std::declval<days>()));
+    ASSERT_SAME_TYPE(day, decltype(std::declval<days>() + std::declval<day>()));
+    
+    static_assert(testConstexpr<day, days>(), "");
+
+    day dy{12};
+    for (unsigned i = 0; i <= 10; ++i)
+    {
+        day d1 = dy + days{i};
+        day d2 = days{i} + dy;
+        assert(d1 == d2);
+        assert(static_cast<unsigned>(d1) == i + 12);
+        assert(static_cast<unsigned>(d2) == i + 12);
+    }
+}