Intl.DateTimeFormat polyfill doesn't support Etc/GMT[+-]{offset} timezones

[kevindetry]

Which package?

@formatjs/intl-datetimeformat

Describe the bug

Intl.DateTimeFormat polyfill throws an Invalid timeZoneName error if the timezone is set to Etc/GMT+0 (or any other Etc/GMT[+-]{offset}).

To Reproduce

Codesandbox URL

https://codesandbox.io/s/wizardly-jones-x9g8s (formatting is broken and error is displayed in console)

Expected behavior

Etc/GMT[+-]{offset} timezones should be supported since they're part of tzdata.

Additional context

This change in luxon library revealed the issue. There's also a link to the Chrome issue tracker, where they've discussed those timezones.

[longlho]

Etc/GMT+0 and such are not valid iana timezone names afaik

[kevindetry]

They seem to be valid:

$ curl -O https://data.iana.org/time-zones/releases/tzdb-2021a.tar.lz
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  481k  100  481k    0     0   633k      0 --:--:-- --:--:-- --:--:--  632k
$ tar xf tzdb-2021a.tar.lz
$ cd tzdb-2021a/
$ make zonenames | grep Etc/GMT
Etc/GMT
Etc/GMT-0
Etc/GMT+0
Etc/GMT0
Etc/GMT-14
Etc/GMT-13
Etc/GMT-12
Etc/GMT-11
Etc/GMT-10
Etc/GMT-9
Etc/GMT-8
Etc/GMT-7
Etc/GMT-6
Etc/GMT-5
Etc/GMT-4
Etc/GMT-3
Etc/GMT-2
Etc/GMT-1
Etc/GMT+1
Etc/GMT+2
Etc/GMT+3
Etc/GMT+4
Etc/GMT+5
Etc/GMT+6
Etc/GMT+7
Etc/GMT+8
Etc/GMT+9
Etc/GMT+10
Etc/GMT+11
Etc/GMT+12

[longlho]

Hmm you're right we'll take a look