1 files changed, 53 insertions, 0 deletions
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.members/decrement.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.members/decrement.pass.cpp
new file mode 100644
index 00000000000..bc39bbc31bd
--- /dev/null
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.members/decrement.pass.cpp
@@ -0,0 +1,53 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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 month;
+
+//  constexpr month& operator--() noexcept;
+//  constexpr month operator--(int) noexcept;
+
+
+#include <chrono>
+#include <type_traits>
+#include <cassert>
+
+#include "test_macros.h"
+
+template <typename M>
+constexpr bool testConstexpr()
+{
+    M m1{10};
+    if (static_cast<unsigned>(--m1) != 9) return false;
+    if (static_cast<unsigned>(m1--) != 9) return false;
+    if (static_cast<unsigned>(m1)   != 8) return false;
+    return true;
+}
+
+int main()
+{
+    using month = std::chrono::month;
+    
+    ASSERT_NOEXCEPT(--(std::declval<month&>())  );
+    ASSERT_NOEXCEPT(  (std::declval<month&>())--);
+
+    ASSERT_SAME_TYPE(month , decltype(  std::declval<month&>()--));
+    ASSERT_SAME_TYPE(month&, decltype(--std::declval<month&>()  ));
+    
+    static_assert(testConstexpr<month>(), "");
+
+    for (unsigned i = 10; i <= 20; ++i)
+    {
+        month month(i);
+        assert(static_cast<unsigned>(--month) == i - 1);
+        assert(static_cast<unsigned>(month--) == i - 1);
+        assert(static_cast<unsigned>(month)   == i - 2);
+    }
+}