Merge pull request #10513 from ClickHouse/fix-fractional-timezones-overflow

Fix overflow at beginning of unix epoch for fractional timezones

base/common/DateLUTImpl.h

@@ -287,8 +287,8 @@ public:
         if (offset_is_whole_number_of_hours_everytime)
             return (t / 60) % 60;
 
-        time_t date = find(t).date;
-        return (t - date) / 60 % 60;
+        UInt32 date = find(t).date;
+        return (UInt32(t) - date) / 60 % 60;
     }
 
     inline time_t toStartOfMinute(time_t t) const { return t / 60 * 60; }
@@ -301,9 +301,8 @@ public:
         if (offset_is_whole_number_of_hours_everytime)
             return t / 3600 * 3600;
 
-        time_t date = find(t).date;
-        /// Still can return wrong values for time at 1970-01-01 if the UTC offset was non-whole number of hours.
-        return date + (t - date) / 3600 * 3600;
+        UInt32 date = find(t).date;
+        return date + (UInt32(t) - date) / 3600 * 3600;
     }
 
     /** Number of calendar day since the beginning of UNIX epoch (1970-01-01 is zero)

tests/queries/0_stateless/01262_fractional_timezone_near_start_of_epoch.reference

+1970-01-01 08:16:40
+16
+1970-01-01 08:00:00

tests/queries/0_stateless/01262_fractional_timezone_near_start_of_epoch.sql

+SELECT toDateTime(10000, 'Asia/Calcutta');
+SELECT toMinute(toDateTime(10000, 'Asia/Calcutta'));
+SELECT toStartOfHour(toDateTime(10000, 'Asia/Calcutta'));