diff --git a/test/date_test/op_div_survey.pass.cpp b/test/date_test/op_div_survey.pass.cpp
new file mode 100644
index 0000000..a45d9ff
--- /dev/null
+++ b/test/date_test/op_div_survey.pass.cpp
@@ -0,0 +1,437 @@
+// The MIT License (MIT)
+// 
+// Copyright (c) 2015 Howard Hinnant
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+#include "date.h"
+
+#include <type_traits>
+
+template <class I, class J, class K>
+constexpr
+auto
+test(I i, J j, K k) -> decltype(i/j/k)
+{
+    return i/j/k;
+}
+
+void
+test(...)
+{
+}
+
+int
+main()
+{
+    using std::is_same;
+    using namespace date;
+    
+    static_assert(is_same<decltype(test(        1,         1,         1)), int>{}, "");
+    static_assert(is_same<decltype(test(        1,         1,       1_d)), month_day>{}, "");
+    static_assert(is_same<decltype(test(        1,         1,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(        1,         1,       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(        1,         1,      last)), month_day_last>{}, "");
+    static_assert(is_same<decltype(test(        1,         1,    sun[1])), month_weekday>{}, "");
+    static_assert(is_same<decltype(test(        1,         1, sun[last])), month_weekday_last>{}, "");
+    
+    static_assert(is_same<decltype(test(        1,       1_d,         1)), year_month_day>{}, "");
+    static_assert(is_same<decltype(test(        1,       1_d,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(        1,       1_d,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(        1,       1_d,       1_y)), year_month_day>{}, "");
+    static_assert(is_same<decltype(test(        1,       1_d,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(        1,       1_d,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(        1,       1_d, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(        1,       jan,         1)), void>{}, "");
+    static_assert(is_same<decltype(test(        1,       jan,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(        1,       jan,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(        1,       jan,       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(        1,       jan,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(        1,       jan,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(        1,       jan, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(        1,       1_y,         1)), void>{}, "");
+    static_assert(is_same<decltype(test(        1,       1_y,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(        1,       1_y,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(        1,       1_y,       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(        1,       1_y,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(        1,       1_y,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(        1,       1_y, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(        1,      last,         1)), year_month_day_last>{}, "");
+    static_assert(is_same<decltype(test(        1,      last,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(        1,      last,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(        1,      last,       1_y)), year_month_day_last>{}, "");
+    static_assert(is_same<decltype(test(        1,      last,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(        1,      last,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(        1,      last, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(        1,    sun[1],         1)), year_month_weekday>{}, "");
+    static_assert(is_same<decltype(test(        1,    sun[1],       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(        1,    sun[1],       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(        1,    sun[1],       1_y)), year_month_weekday>{}, "");
+    static_assert(is_same<decltype(test(        1,    sun[1],      last)), void>{}, "");
+    static_assert(is_same<decltype(test(        1,    sun[1],    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(        1,    sun[1], sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(        1, sun[last],         1)), year_month_weekday_last>{}, "");
+    static_assert(is_same<decltype(test(        1, sun[last],       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(        1, sun[last],       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(        1, sun[last],       1_y)), year_month_weekday_last>{}, "");
+    static_assert(is_same<decltype(test(        1, sun[last],      last)), void>{}, "");
+    static_assert(is_same<decltype(test(        1, sun[last],    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(        1, sun[last], sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(      1_d,         1,         1)), year_month_day>{}, "");
+    static_assert(is_same<decltype(test(      1_d,         1,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,         1,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,         1,       1_y)), year_month_day>{}, "");
+    static_assert(is_same<decltype(test(      1_d,         1,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,         1,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,         1, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(      1_d,       1_d,         1)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,       1_d,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,       1_d,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,       1_d,       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,       1_d,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,       1_d,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,       1_d, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(      1_d,       jan,         1)), year_month_day>{}, "");
+    static_assert(is_same<decltype(test(      1_d,       jan,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,       jan,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,       jan,       1_y)), year_month_day>{}, "");
+    static_assert(is_same<decltype(test(      1_d,       jan,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,       jan,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,       jan, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(      1_d,       1_y,         1)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,       1_y,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,       1_y,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,       1_y,       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,       1_y,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,       1_y,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,       1_y, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(      1_d,      last,         1)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,      last,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,      last,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,      last,       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,      last,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,      last,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,      last, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(      1_d,    sun[1],         1)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,    sun[1],       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,    sun[1],       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,    sun[1],       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,    sun[1],      last)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,    sun[1],    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d,    sun[1], sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(      1_d, sun[last],         1)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d, sun[last],       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d, sun[last],       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d, sun[last],       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d, sun[last],      last)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d, sun[last],    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(      1_d, sun[last], sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(      jan,         1,         1)), year_month_day>{}, "");
+    static_assert(is_same<decltype(test(      jan,         1,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,         1,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,         1,       1_y)), year_month_day>{}, "");
+    static_assert(is_same<decltype(test(      jan,         1,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,         1,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,         1, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(      jan,       1_d,         1)), year_month_day>{}, "");
+    static_assert(is_same<decltype(test(      jan,       1_d,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,       1_d,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,       1_d,       1_y)), year_month_day>{}, "");
+    static_assert(is_same<decltype(test(      jan,       1_d,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,       1_d,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,       1_d, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(      jan,       jan,         1)), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,       jan,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,       jan,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,       jan,       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,       jan,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,       jan,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,       jan, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(      jan,       1_y,         1)), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,       1_y,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,       1_y,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,       1_y,       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,       1_y,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,       1_y,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,       1_y, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(      jan,      last,         1)), year_month_day_last>{}, "");
+    static_assert(is_same<decltype(test(      jan,      last,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,      last,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,      last,       1_y)), year_month_day_last>{}, "");
+    static_assert(is_same<decltype(test(      jan,      last,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,      last,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,      last, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(      jan,    sun[1],         1)), year_month_weekday>{}, "");
+    static_assert(is_same<decltype(test(      jan,    sun[1],       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,    sun[1],       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,    sun[1],       1_y)), year_month_weekday>{}, "");
+    static_assert(is_same<decltype(test(      jan,    sun[1],      last)), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,    sun[1],    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(      jan,    sun[1], sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(      jan, sun[last],         1)), year_month_weekday_last>{}, "");
+    static_assert(is_same<decltype(test(      jan, sun[last],       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(      jan, sun[last],       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(      jan, sun[last],       1_y)), year_month_weekday_last>{}, "");
+    static_assert(is_same<decltype(test(      jan, sun[last],      last)), void>{}, "");
+    static_assert(is_same<decltype(test(      jan, sun[last],    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(      jan, sun[last], sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(      1_y,         1,         1)), year_month_day>{}, "");
+    static_assert(is_same<decltype(test(      1_y,         1,       1_d)), year_month_day>{}, "");
+    static_assert(is_same<decltype(test(      1_y,         1,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,         1,       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,         1,      last)), year_month_day_last>{}, "");
+    static_assert(is_same<decltype(test(      1_y,         1,    sun[1])), year_month_weekday>{}, "");
+    static_assert(is_same<decltype(test(      1_y,         1, sun[last])), year_month_weekday_last>{}, "");
+    
+    static_assert(is_same<decltype(test(      1_y,       1_d,         1)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,       1_d,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,       1_d,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,       1_d,       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,       1_d,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,       1_d,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,       1_d, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(      1_y,       jan,         1)), year_month_day>{}, "");
+    static_assert(is_same<decltype(test(      1_y,       jan,       1_d)), year_month_day>{}, "");
+    static_assert(is_same<decltype(test(      1_y,       jan,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,       jan,       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,       jan,      last)), year_month_day_last>{}, "");
+    static_assert(is_same<decltype(test(      1_y,       jan,    sun[1])), year_month_weekday>{}, "");
+    static_assert(is_same<decltype(test(      1_y,       jan, sun[last])), year_month_weekday_last>{}, "");
+    
+    static_assert(is_same<decltype(test(      1_y,       1_y,         1)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,       1_y,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,       1_y,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,       1_y,       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,       1_y,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,       1_y,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,       1_y, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(      1_y,      last,         1)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,      last,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,      last,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,      last,       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,      last,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,      last,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,      last, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(      1_y,    sun[1],         1)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,    sun[1],       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,    sun[1],       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,    sun[1],       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,    sun[1],      last)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,    sun[1],    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y,    sun[1], sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(      1_y, sun[last],         1)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y, sun[last],       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y, sun[last],       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y, sun[last],       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y, sun[last],      last)), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y, sun[last],    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(      1_y, sun[last], sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(     last,         1,         1)), year_month_day_last>{}, "");
+    static_assert(is_same<decltype(test(     last,         1,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(     last,         1,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(     last,         1,       1_y)), year_month_day_last>{}, "");
+    static_assert(is_same<decltype(test(     last,         1,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(     last,         1,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(     last,         1, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(     last,       1_d,         1)), void>{}, "");
+    static_assert(is_same<decltype(test(     last,       1_d,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(     last,       1_d,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(     last,       1_d,       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(     last,       1_d,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(     last,       1_d,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(     last,       1_d, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(     last,       jan,         1)), year_month_day_last>{}, "");
+    static_assert(is_same<decltype(test(     last,       jan,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(     last,       jan,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(     last,       jan,       1_y)), year_month_day_last>{}, "");
+    static_assert(is_same<decltype(test(     last,       jan,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(     last,       jan,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(     last,       jan, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(     last,       1_y,         1)), void>{}, "");
+    static_assert(is_same<decltype(test(     last,       1_y,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(     last,       1_y,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(     last,       1_y,       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(     last,       1_y,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(     last,       1_y,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(     last,       1_y, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(     last,      last,         1)), void>{}, "");
+    static_assert(is_same<decltype(test(     last,      last,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(     last,      last,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(     last,      last,       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(     last,      last,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(     last,      last,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(     last,      last, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(     last,    sun[1],         1)), void>{}, "");
+    static_assert(is_same<decltype(test(     last,    sun[1],       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(     last,    sun[1],       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(     last,    sun[1],       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(     last,    sun[1],      last)), void>{}, "");
+    static_assert(is_same<decltype(test(     last,    sun[1],    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(     last,    sun[1], sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(     last, sun[last],         1)), void>{}, "");
+    static_assert(is_same<decltype(test(     last, sun[last],       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(     last, sun[last],       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(     last, sun[last],       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(     last, sun[last],      last)), void>{}, "");
+    static_assert(is_same<decltype(test(     last, sun[last],    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(     last, sun[last], sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(   sun[1],         1,         1)), year_month_weekday>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],         1,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],         1,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],         1,       1_y)), year_month_weekday>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],         1,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],         1,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],         1, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(   sun[1],       1_d,         1)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],       1_d,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],       1_d,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],       1_d,       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],       1_d,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],       1_d,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],       1_d, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(   sun[1],       jan,         1)), year_month_weekday>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],       jan,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],       jan,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],       jan,       1_y)), year_month_weekday>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],       jan,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],       jan,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],       jan, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(   sun[1],       1_y,         1)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],       1_y,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],       1_y,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],       1_y,       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],       1_y,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],       1_y,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],       1_y, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(   sun[1],      last,         1)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],      last,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],      last,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],      last,       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],      last,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],      last,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],      last, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(   sun[1],    sun[1],         1)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],    sun[1],       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],    sun[1],       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],    sun[1],       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],    sun[1],      last)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],    sun[1],    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1],    sun[1], sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(   sun[1], sun[last],         1)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1], sun[last],       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1], sun[last],       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1], sun[last],       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1], sun[last],      last)), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1], sun[last],    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(   sun[1], sun[last], sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(sun[last],         1,         1)), year_month_weekday_last>{}, "");
+    static_assert(is_same<decltype(test(sun[last],         1,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],         1,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],         1,       1_y)), year_month_weekday_last>{}, "");
+    static_assert(is_same<decltype(test(sun[last],         1,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],         1,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],         1, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(sun[last],       1_d,         1)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],       1_d,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],       1_d,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],       1_d,       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],       1_d,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],       1_d,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],       1_d, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(sun[last],       jan,         1)), year_month_weekday_last>{}, "");
+    static_assert(is_same<decltype(test(sun[last],       jan,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],       jan,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],       jan,       1_y)), year_month_weekday_last>{}, "");
+    static_assert(is_same<decltype(test(sun[last],       jan,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],       jan,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],       jan, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(sun[last],       1_y,         1)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],       1_y,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],       1_y,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],       1_y,       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],       1_y,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],       1_y,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],       1_y, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(sun[last],      last,         1)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],      last,       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],      last,       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],      last,       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],      last,      last)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],      last,    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],      last, sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(sun[last],    sun[1],         1)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],    sun[1],       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],    sun[1],       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],    sun[1],       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],    sun[1],      last)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],    sun[1],    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last],    sun[1], sun[last])), void>{}, "");
+    
+    static_assert(is_same<decltype(test(sun[last], sun[last],         1)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last], sun[last],       1_d)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last], sun[last],       jan)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last], sun[last],       1_y)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last], sun[last],      last)), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last], sun[last],    sun[1])), void>{}, "");
+    static_assert(is_same<decltype(test(sun[last], sun[last], sun[last])), void>{}, "");
+}