[DST] Wrong date when adding one day

[AndreLorenz]

Hello!!

I need to add one day before DST, but when I set moment.tz.setDefault to "America/Sao_Paulo" and add one day to October 20, 2018 the moment returns the same day at 11:00PM instead of October 21, 2018 at 01:00AM.

Already when I reset tz (setDefault()) it returns the correct date.

moment.tz.setDefault() // Reset tz
moment('10/20/2018', "MM/DD/YYYY").startOf('day').add(1, 'day').format()
// "2018-10-21T01:00:00-02:00" (Correct date)

moment.tz.guess()
// "America/Sao_Paulo"
moment.tz.setDefault(moment.tz.guess())
moment('10/20/2018', "MM/DD/YYYY").startOf('day').add(1, 'day').format()
// "2018-10-20T23:00:00-03:00" (Incorrect date)

Workaround for this issue:

moment.tz.guess()
// "America/Sao_Paulo"
moment.tz.setDefault(moment.tz.guess())
const date = moment('10/20/2018', "MM/DD/YYYY").hour(12).add(1, 'day')
date.startOf('day').format()
// "2018-10-21T01:00:00-02:00" (Correct date)

Thanks

[ellenaua]

FYI: this happens because data/latest.json contains invalid dates of time change for America/Sao_Paulo

86= 2017-02-19T02:00:00.000Z
87= 2017-10-15T03:00:00.000Z
88= 2018-02-18T02:00:00.000Z
89= 2018-10-21T03:00:00.000Z
90= 2019-02-17T02:00:00.000Z
91= 2019-10-20T03:00:00.000Z

Time change was on 2018-02-18 this February, but next time change will be not on 2018-10-21 but on 2018-11-04 (I check here https://www.timeanddate.com/time/zone/brazil/sao-paulo)
So, data/latest.json contains invalid data.

Because of that, when user adds +1 day, it adds +1 day and -1 hour (library thinks that time change happens on 2018-10-21) so user gets same day 23:00

[ellenaua]

This PR will deliver updated data #577

[ellenaua]

@AndreLorenz in moment-timezone 0.5.16 this problem does not happen for 10/20/2018, but happens for 11/03/2018 because Clock Change is happening on 11/04/2018 00:00 according to updated data from IANA TZ database.

moment.tz.setDefault('America/Sao_Paulo');
const v1 = moment('11/03/2018', "MM/DD/YYYY").startOf('day').add(1, 'day');
const v2 = moment('11/03/2018', "MM/DD/YYYY").startOf('day').add(24, 'hour');
console.log(v1.toString()); // Sat Nov 03 2018 23:00:00 GMT-0300
console.log(v2.toString()); // Sun Nov 04 2018 01:00:00 GMT-0200

I'll post more info about this issue later.

[joshwils82]

I am experiencing this issue as well. Any chance this could get fixed soon?

[mattjohnsonpint]

Duplicate of #409. Tracking there. Thanks.