1365192 - getTimezoneOffset() returns incorrect values in Asuncion time zone

Status: RESOLVED DUPLICATE of bug 1346211

(Core :: JavaScript: Internationalization API, defect, P3)

Description

[mak0702]

User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Firefox/52.0
Build ID: 20170504112025

Steps to reproduce:

In Asuncion, DST starts on the 1st Sunday of October and ends on the 4th Sunday of March (see https://www.timeanddate.com/time/change/paraguay/asuncion). 

During DST, Date.getTimezoneOffset() should return 180, otherwise 240.

- Set OS time zone to Asuncion (I confirmed the issue on Windows).
- Call "new Date(2018, 2, 31).getTimezoneOffset()" on the console. Note this date (March 31, 2018) is outside DST.


Actual results:

180 is returned, which means that the JS engine thinks this date to be inside DST.


Expected results:

240 should be returned.

Comment 1

[André Bargull [:anba]]

Dup'ing forward to bug 1346211 which should have fixed this problem. Please reopen if the issue is still present. Thanks!