system_clock::duration and steady_clock::duration can be different types

Author: dgoffredo

src/datadog/clock.h

@@ -39,11 +39,15 @@ inline Duration operator-(const TimePoint& after, const TimePoint& before) {
 }
 
 inline TimePoint operator-(const TimePoint& origin, Duration offset) {
-  return {origin.wall - offset, origin.tick - offset};
+  return {origin.wall -
+              std::chrono::duration_cast<std::chrono::system_clock::duration>(
+                  offset),
+          origin.tick - offset};
 }
 
 inline TimePoint& operator+=(TimePoint& self, Duration offset) {
-  self.wall += offset;
+  self.wall +=
+      std::chrono::duration_cast<std::chrono::system_clock::duration>(offset);
   self.tick += offset;
   return self;
 }