<![CDATA[Today in Web compat: Firefox and Safari are ahead of Chrome in ICU4C version and upsteam ICU4C changed the formatting of zero offset from GMT.]]>Today in Web compat: Firefox and Safari are ahead of Chrome in ICU4C version and upsteam ICU4C changed the formatting of zero offset from GMT. This broke birthday date validation for a UK based site for birthdays before 1970 in Firefox and, on 26.x Apple OSs, in Safari, because the site performs a formatting-based check on the time zone of London on the date to be validated and the UK has changed time zone rules along the way.

]]>https://board.circlewithadot.net/topic/7ad3dd0f-2e9c-40eb-a860-a61ce52de668/today-in-web-compat-firefox-and-safari-are-ahead-of-chrome-in-icu4c-version-and-upsteam-icu4c-changed-the-formatting-of-zero-offset-from-gmt.RSS for NodeWed, 15 Apr 2026 14:04:15 GMTWed, 25 Mar 2026 11:17:42 GMT60<![CDATA[Reply to Today in Web compat: Firefox and Safari are ahead of Chrome in ICU4C version and upsteam ICU4C changed the formatting of zero offset from GMT. on Wed, 01 Apr 2026 10:44:04 GMT]]>@hsivonen Uh, oh!

]]>https://board.circlewithadot.net/post/https://social.mkj.earth/users/mkj/statuses/116329037446742946https://board.circlewithadot.net/post/https://social.mkj.earth/users/mkj/statuses/116329037446742946Wed, 01 Apr 2026 10:44:04 GMT<![CDATA[Reply to Today in Web compat: Firefox and Safari are ahead of Chrome in ICU4C version and upsteam ICU4C changed the formatting of zero offset from GMT. on Wed, 01 Apr 2026 10:35:24 GMT]]>@mkj Nope, due to the British Standard Time Act of 1968. Thanks to your toot, I realized that my fix was wrong!

(This looks like time zone satire or April Fools, but, unfortunately, I’m not joking.)

]]>https://board.circlewithadot.net/post/https://mastodon.social/users/hsivonen/statuses/116329003390230241https://board.circlewithadot.net/post/https://mastodon.social/users/hsivonen/statuses/116329003390230241Wed, 01 Apr 2026 10:35:24 GMT<![CDATA[Reply to Today in Web compat: Firefox and Safari are ahead of Chrome in ICU4C version and upsteam ICU4C changed the formatting of zero offset from GMT. on Tue, 31 Mar 2026 09:15:50 GMT]]>@hsivonen Presumably this includes everyone born on 1970-01-01? 🙂

]]>https://board.circlewithadot.net/post/https://social.mkj.earth/users/mkj/statuses/116323028176854736https://board.circlewithadot.net/post/https://social.mkj.earth/users/mkj/statuses/116323028176854736Tue, 31 Mar 2026 09:15:50 GMT<![CDATA[Reply to Today in Web compat: Firefox and Safari are ahead of Chrome in ICU4C version and upsteam ICU4C changed the formatting of zero offset from GMT. on Tue, 31 Mar 2026 07:37:06 GMT]]>The time zone and daylight-saving time fans out there will probably appreciate the user impact description that I wrote for release management:

“Users whose birthday is before the end of October 1971 on a day when the UK was not observing daylight-saving time can't sign up for online banking at a particular British bank.”

]]>https://board.circlewithadot.net/post/https://mastodon.social/users/hsivonen/statuses/116322639990962409https://board.circlewithadot.net/post/https://mastodon.social/users/hsivonen/statuses/116322639990962409Tue, 31 Mar 2026 07:37:06 GMT<![CDATA[Reply to Today in Web compat: Firefox and Safari are ahead of Chrome in ICU4C version and upsteam ICU4C changed the formatting of zero offset from GMT. on Tue, 31 Mar 2026 07:34:38 GMT]]>It turned out that some time zones that use “GMT” as their abbreviation in the same style as CET for Central European Time or PDT for Pacific Daylight-saving Time previously got “GMT” by a different mechanism, so an intentional change to that mechanism had unintended effects.

]]>https://board.circlewithadot.net/post/https://mastodon.social/users/hsivonen/statuses/116322630288168795https://board.circlewithadot.net/post/https://mastodon.social/users/hsivonen/statuses/116322630288168795Tue, 31 Mar 2026 07:34:38 GMT