This PR was squashed before being merged into the 4.2-dev branch (closes#28070).
Discussion
----------
[Translator] Use ICU parent locales as fallback locales
| Q | A
| ------------- | ---
| Branch? | master
| Bug fix? | no
| New feature? | yes
| BC breaks? | no
| Deprecations? | no
| Tests pass? | yes
| Fixed tickets | #12319
| License | MIT
| Doc PR | https://github.com/symfony/symfony-docs/pull/10122
Currently the `Translator` fall backs based on the locale separator (eg `es_AR` to `es`), but the ICU data contains parent locales (eg `es_AR` is a child of `es_419`, as is `es_BO`, `es_EC` etc).
This makes use of the ICU data to add add in these fallbacks. This means the specific locales can be used, but the translations can stored in these groupings (eg `es_419` for Latin American Spanish), as well as adding other sensible fallbacks (eg Cape Verdean Portuguese to `pt_PT`).
Commits
-------
e0f402fc29 [Translator] Use ICU parent locales as fallback locales
