cast expression

Signed-off-by: Rosen Penev <rosenp@gmail.com>

src/value.cpp

@@ -994,7 +994,7 @@ std::ostream& TimeValue::write(std::ostream& os) const {
 
 int64_t TimeValue::toInt64(size_t /*n*/) const {
   // Returns number of seconds in the day in UTC.
-  int64_t result = (time_.hour - time_.tzHour) * 60 * 60;
+  auto result = static_cast<int64_t>(time_.hour - time_.tzHour) * 60 * 60;
   result += (time_.minute - time_.tzMinute) * 60;
   result += time_.second;
   if (result < 0) {