lzorglub / timezone Goto Github PK

I was trying to investigate an issue reported here: http://mm.icann.org/pipermail/tz/2018-July/026698.html

I decided to implement a tzvalidate dump for Afk.TimeZone, but in doing so I found a problem that it's hard to get past.

The "America/Argentina/Buenos_Aires" time zone seems to get "stuck" for at least some time at 1998-12-31T23:56:15Z. Here's a program to demonstrate:

using System;
using System.Linq;
using Afk.ZoneInfo;

class Program
{
    static void Main(string[] args)
    {
        var zone = TzTimeInfo.GetZones().Single(z => z.Name == "America/Argentina/Buenos_Aires");
        
        var start = new DateTime(1998, 12, 31, 23, 56, 15, DateTimeKind.Utc);
        
        for (int i = 0; i < 10; i++)
        {
            Console.WriteLine(zone.ToLocalTime(start.AddTicks(i)).Ticks);
        }
    }
}

The output is:

630507345750000000
630507345750000000
630507345750000000
630507345750000000
630507345750000000
630507345750000000
630507345750000000
630507345750000000
630507345750000000
630507345750000000

That basically suggests that the wall clock stands still for at least those 10 ticks, which shouldn't happen.

I'm going to try to hard-code a workaround for this to start with, but it's not clear whether that will be sufficient.

Values provided for America/Grand_Turk year 2018 are incorrect.
The optimized algorithm (prefetch of DST changes) retrieve the wrong DST value.

Version 2.2 use now by default the normal algorithm before fix.

When I download the files manually, I get an exception. "The type initializer for 'Afk.ZoneInfo.TzTimeInfo' threw an exception."

I looked at it a little in the debugger and it seems there is some duplicate key error. BTW, it seems that it happens even with the current files. I copied the current files in the data folder to another folder and defined that folder in the env var TZDIR and the same thing happens.

Just to be clear, I just download https://www.iana.org/time-zones/repository/tzdata-latest.tar.gz and unpack it into a directory. That is my TZDIR.

For some dates,when i convert local tome to utc and reverse utc to local,then local dates aren't same.
this is my test that reproduce the bug:

       [TestMethod]
       public void ToUtcAndReverse()
       {
           var timeZoneProvider = new AfkTimeZoneProvider();
           const string IranStandardTime = "Iran Standard Time";

           var errors = new List<string>();
           var currentDate = new DateTime(1940, 1, 1);
           var maxDate = new DateTime(2040, 1, 1);

           for (var i = 1; i < 10000000; i++)
           {
               var utcDate = timeZoneProvider.ToUtc(currentDate, IranStandardTime);

               var localDate = timeZoneProvider.ToLocal(utcDate, IranStandardTime);


               if (currentDate.Date != localDate.Date)
               {
                   errors.Add(currentDate.ToLongDateString());
               }

               currentDate = currentDate.AddDays(1);

               
               if (currentDate > maxDate)
               {
                   break;
               }
           }

           if (errors.Any())
           {
               Assert.Fail();
           }
       }