custom clock and noncastable tests

test/clock_cast_test/custom_clock.pass.cpp

@@ -56,6 +56,23 @@ struct mil_clock
     return res(tp - epoch);
   }
 
+  template<typename Duration>
+  static
+  std::chrono::time_point<date::local_t, typename std::common_type<Duration, date::days>::type>
+  to_local(std::chrono::time_point<mil_clock, Duration> const& tp)
+  {
+     return date::clock_cast<date::local_t>(to_sys(tp));
+  }
+
+  template<typename Duration>
+  static
+  std::chrono::time_point<mil_clock, typename std::common_type<Duration, date::days>::type>
+  from_local(std::chrono::time_point<date::local_t, Duration> const& tp)
+  {
+    return from_sys(date::clock_cast<std::chrono::system_clock>(tp));
+  }
+
+
   static time_point now()
   {
     return from_sys(std::chrono::system_clock::now());
@@ -127,6 +144,15 @@ main()
        assert(clock_cast<mil_clock>(mt) == mt);
     }
 
+    // mil <-> local
+    {
+       local_days lt(1997_y/dec/12);
+       auto mt = mil_clock::from_local(lt);
+
+       assert(clock_cast<mil_clock>(lt) == mt);
+       assert(clock_cast<local_t>(mt) == lt);
+    }
+
     // mil <-> sys
     {
        sys_days st(1997_y/dec/12);