TimestampWithTimeZone not handling ambiguous values

[yuandagits]

Presto is returning different values for date_add(-7, FOO_TIME) and FOO_TIME - INTERVAL '7' HOUR. Specifically, when a string is passed into parse_datetime(), and the output of this fed into date_trunc('hour', ...) - INTERVAL '7' HOUR, we are observing two different values.

We think that this may be an issue with TimestampWithTImeZones here:

presto/presto-main/src/main/java/com/facebook/presto/type/DateTimeOperators.java

Lines 105 to 109 in 70af20f

	@ScalarOperator(ADD)
	@SqlType(StandardTypes.TIMESTAMP_WITH_TIME_ZONE)
	public static long timestampWithTimeZonePlusIntervalDayToSecond(@SqlType(StandardTypes.TIMESTAMP_WITH_TIME_ZONE) long left, @SqlType(StandardTypes.INTERVAL_DAY_TO_SECOND) long right)
	{
	return updateMillisUtc(unpackMillisUtc(left) + right, left);

not handling timezones in the case of ambiguous values.

Expected Behavior

select to_unixtime(date_trunc('hour',
    parse_datetime(
        concat(substr('2024-11-03+07:00:99', 1, 17), '00'),
        'yyyy-MM-dd+HH:mm:ss'
    ) - INTERVAL '7' HOUR)) -> 1,730,620,800


select to_unixtime(date_trunc('hour',
    parse_datetime(
        concat(substr('2024-11-03+08:00:99', 1, 17), '00'),
        'yyyy-MM-dd+HH:mm:ss'
    ) - INTERVAL '7' HOUR)) -> 1,730,620,800

Current Behavior

select to_unixtime(date_trunc('hour',
    parse_datetime(
        concat(substr('2024-11-03+08:00:99', 1, 17), '00'),
        'yyyy-MM-dd+HH:mm:ss'
    ) - INTERVAL '7' HOUR)) -> 1,730,624,400
  
select to_unixtime(date_trunc('hour',
    parse_datetime(
        concat(substr('2024-11-03+07:00:99', 1, 17), '00'),
        'yyyy-MM-dd+HH:mm:ss'
    ) - INTERVAL '7' HOUR)) -> 1,730,620,800