Hello.

I just hit an issue with the country type and the Intl component.

According to PHP, the first parameter of Locale::setDefault
should be a BCP 47 compliant tag.

So according to the RFC, it should be something like fr or fr-FR.
In my case it's fr-FR.

Now the CountryType use the Locale::getDefault. Refs:

• https://github.com/symfony/symfony/blob/v3.3.8/src/Symfony/Component/Form/Extension/Core/Type/CountryType.php#L78
• ...
• https://github.com/symfony/symfony/blob/v3.3.8/src/Symfony/Component/Intl/Data/Provider/RegionDataProvider.php#L67

Then symfony will use will default locale to find the best locale by "fallbacking" on "wider" locale (fr_FR -> fr)

And here
there is something wrong IMHO. Symfony only try to split the local with an underscore (_) and not
with a dash (-). But the RFC states the locale should use an underscore and not a dash.

Some facts to take in consideration:

• The Translator component use another RFC for the format of the locale. (fr_FR);
• The Validator component use another RFC for the format of the locale. (fr_FR);
• It's really weird I'm the first one to hit this issue => Did I miss something ?

What I suggest: We could update the Locale::getFallback method to support splitting on -.

WDYT? I can make the PR if this RFC is accepted.

I pushed a reproducer