This PR was merged into the 4.2-dev branch.

Discussion
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[Form] Deprecate TimezoneType regions option

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no     <!-- see https://symfony.com/bc -->
| Deprecations? | yes
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| Fixed tickets | #28848
| License       | MIT
| Doc PR        | symfony/symfony-docs#... <!-- required for new features -->

I know i've added this option myself in 4.1, but given my recent development for #28624 i realized it's an opinionated feaure, which can/should be solved on user-side (`choice_filter/choice_loader` and/or `group_by`).

- blocks translations as we dont have them (see #28831)
- blocks possibility of switching to Intl zones which doesnt really have this filter feature (see #28836)

~While at it, i solved a few issues with `OptionsResolver` that is able to deprecate options as of 4.2 also.~ Fixed in #28878

- when resolved trigger the deprecation
- allow to opt-out from triggering the deprecation
- dont trigger deprecation for default values (only given ones)

Commits
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5cb532d [Form] Deprecate TimezoneType regions option

This PR was squashed before being merged into the 4.3-dev branch (closes #31195).

Discussion
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[Form] Add intltimezone input to TimezoneType

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no     <!-- see https://symfony.com/bc -->
| Deprecations? | no
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| Fixed tickets | #22302 (ref #28836)
| License       | MIT
| Doc PR        | symfony/symfony-docs#11463

cc @rvanlaak

Commits
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e169dfb [Form] Add intltimezone input to TimezoneType

…country mapping (ro0NL)

This PR was squashed before being merged into the 4.3-dev branch (closes #31262).

Discussion
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[Intl] Update timezones to ICU 64.2 + compile zone to country mapping

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no     <!-- see https://symfony.com/bc -->
| Deprecations? | no
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| Fixed tickets | #...   <!-- #-prefixed issue number(s), if any -->
| License       | MIT
| Doc PR        | symfony/symfony-docs#... <!-- required for new features -->

This PR compiles the zone to country mapping (and vice versa) from ICU data:
https://github.com/unicode-org/icu/blob/master/icu4c/source/data/misc/windowsZones.txt

I've recompiled timezones on master due #31162, i should do it once more when it's merged upstream.

Having this data allows compatibility between PHP timezones and ICU;
- https://www.php.net/manual/en/intltimezone.getregion.php
- https://www.php.net/manual/en/class.datetimezone.php#datetimezone.constants.per-country

For the timezone validator in Symfony, this would be required to have a compatible "regions" option, once it supports ICU as well (#28836 (comment))

Commits
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3018a7a [Intl] Update timezones to ICU 64.2 + compile zone to country mapping

This PR was merged into the 4.3-dev branch.

Discussion
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[Validator] Allow intl timezones

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no     <!-- see https://symfony.com/bc -->
| Deprecations? | no
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| Fixed tickets | ref #28836
| License       | MIT
| Doc PR        | symfony/symfony-docs#11502

This PR considers the ICU timezones (#28831) as valid, as well as the PHP ones.

Both can be used in `DateTimeZone`, but expired timezones cannot be used with `IntlTimeZone`. The `intlCompatibility` option ensures compatibility between both.

Practically this allows for both `UTC` and `Etc/UTC`, where the latter should be preferred. I.e. currently `Etc/UTC` is considered an invalid timezone ... which it's not.

Commits
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7294b59 [Validator] Allow intl timezones

…mezoneType (ro0NL)

This PR was merged into the 4.3 branch.

Discussion
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[Form] Add intl/choice_translation_locale option to TimezoneType

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no     <!-- see https://symfony.com/bc -->
| Deprecations? | no
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| Fixed tickets | #28836
| License       | MIT
| Doc PR        | symfony/symfony-docs#11503

final step :)

for now i think any form of grouping is a user concern (i.e. by GMT offset or area name); see #31293 + #31295

having a special built in `group_by' => 'gmt_offset'` util would be nice, and can be done in the future.

includes #31434

Commits
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001b930 [Form] Add intl/choice_translation_locale option to TimezoneType