Template abstract_clock on Clock:

The abstract_clock is now templated on a type meeting the requirements of
the Clock concept. It inherits the nested types of the Clock on which it
is based. This resolves a problem with the original design which broke the
type-safety of time_point from different abstract clocks.

beast/container/aged_map.h

@@ -31,12 +31,12 @@ namespace beast {
 template <
     class Key,
     class T,
-    class Duration = std::chrono::seconds,
+    class Clock = std::chrono::steady_clock,
     class Compare = std::less <Key>,
     class Allocator = std::allocator <std::pair <Key const, T>>
 >
 using aged_map = detail::aged_ordered_container <
-    false, true, Key, T, Duration, Compare, Allocator>;
+    false, true, Key, T, Clock, Compare, Allocator>;
 
 }