Can someone point me to the problem?

Can someone point me to the problem?

I have this code:

var
  dt, dt2: TDateTime;
  v: Variant;
begin
  dt := EncodeDateTime(2015, 1, 1, 12, 0, 0, 0);
  v := VarSQLTimeStampOffsetCreate(dt);
  dt2 := v;

dt2 is 01.01.2015 11:00:00 

After debugging I found the explanation but I have no clue where exactly the bug lies.

VarSQLTimeStampOffsetCreate internally saves the current timezone which is UTC+2 here (CEST). When converting back it uses TTimeZone.Local.ToLocalTime which does "the trick". It looks if the value passed is within a DST and only then applies the DST offset. Since 1.1.2015 is winter time it only adds the +1 for CET and not the +2 that it originally stored.

I know timezones and stuff can make you crazy but in that case it is just converting back and forth and the result is wrong. My guess is that UTCToLocal from SqlTimSt should not use TTimezone.Local.ToLocal since that uses that extra magic. Or it should use it ALSO when creating the value so it would store +1 in that case and not +2.

Edit:
Ok, I guess this function is wrong:

function DateTimeToSQLTimeStampOffset(const DateTime: TDateTime): TSQLTimeStampOffset;
begin
  Result := DateTimeToSQLTimeStampOffset(DateTime, TTimeZone.Local.UtcOffset.Hours, TTimeZone.Local.UtcOffset.Minutes);
end;

if should be:
function DateTimeToSQLTimeStampOffset(const DateTime: TDateTime): TSQLTimeStampOffset;
begin
  Result := DateTimeToSQLTimeStampOffset(DateTime, TTimeZone.Local.GetUtcOffset(DateTime).Hours, TTimeZone.Local.GetUtcOffset(DateTime).Minutes);
end;