feature #32388 [Form] Allow to translate each language into its langu…

…age in LanguageType (javiereguiluz)

This PR was squashed before being merged into the 5.1-dev branch (closes #32388).

Discussion
----------

[Form] Allow to translate each language into its language in LanguageType

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no     <!-- see https://symfony.com/bc -->
| Deprecations? | no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| Fixed tickets | #31562
| License       | MIT
| Doc PR        | I'll do it if this is approved

This would allow to set this option:

```php
->add('language', LanguageType::class, [
    'choice_self_translation' => true,
])
```

To display each language translated into its own language:

![image](https://user-images.githubusercontent.com/73419/60709908-cdf29b80-9f11-11e9-83c8-8ee939c0de3a.png)

@ro0NL if this proposal is approved, could you please tell me why I must `try ... catch` with `\Exception`?

* First, I need the try..catch because of a special language with the code "root" which triggers exceptions (*The resource bundle "symfony-code/src/Symfony/Component/Intl/Resources/data/languages/root.json" does not exist*)
* Second, I must catch \Exception because when I try to catch the exact exception (`Symfony\Component\Intl\Exception\ResourceBundleNotFoundException`) the exception is not caught. Why?

Commits
-------

138200c [Form] Allow to translate each language into its language in LanguageType

src/Symfony/Component/Form/Extension/Core/Type/LanguageType.php

@@ -13,6 +13,8 @@
 
 use Symfony\Component\Form\AbstractType;
 use Symfony\Component\Form\ChoiceList\Loader\IntlCallbackChoiceLoader;
+use Symfony\Component\Form\Exception\LogicException;
+use Symfony\Component\Intl\Exception\MissingResourceException;
 use Symfony\Component\Intl\Languages;
 use Symfony\Component\OptionsResolver\Options;
 use Symfony\Component\OptionsResolver\OptionsResolver;
@@ -27,19 +29,43 @@ public function configureOptions(OptionsResolver $resolver)
         $resolver->setDefaults([
             'choice_loader' => function (Options $options) {
                 $choiceTranslationLocale = $options['choice_translation_locale'];
-                $alpha3 = $options['alpha3'];
+                $useAlpha3Codes = $options['alpha3'];
+                $choiceSelfTranslation = $options['choice_self_translation'];
 
-                return new IntlCallbackChoiceLoader(function () use ($choiceTranslationLocale, $alpha3) {
-                    return array_flip($alpha3 ? Languages::getAlpha3Names($choiceTranslationLocale) : Languages::getNames($choiceTranslationLocale));
+                return new IntlCallbackChoiceLoader(function () use ($choiceTranslationLocale, $useAlpha3Codes, $choiceSelfTranslation) {
+                    if (true === $choiceSelfTranslation) {
+                        foreach (Languages::getLanguageCodes() as $alpha2Code) {
+                            try {
+                                $languageCode = $useAlpha3Codes ? Languages::getAlpha3Code($alpha2Code) : $alpha2Code;
+                                $languagesList[$languageCode] = Languages::getName($alpha2Code, $alpha2Code);
+                            } catch (MissingResourceException $e) {
+                                // ignore errors like "Couldn't read the indices for the locale 'meta'"
+                            }
+                        }
+                    } else {
+                        $languagesList = $useAlpha3Codes ? Languages::getAlpha3Names($choiceTranslationLocale) : Languages::getNames($choiceTranslationLocale);
+                    }
+
+                    return array_flip($languagesList);
                 });
             },
             'choice_translation_domain' => false,
             'choice_translation_locale' => null,
             'alpha3' => false,
+            'choice_self_translation' => false,
         ]);
 
+        $resolver->setAllowedTypes('choice_self_translation', ['bool']);
         $resolver->setAllowedTypes('choice_translation_locale', ['null', 'string']);
         $resolver->setAllowedTypes('alpha3', 'bool');
+
+        $resolver->setNormalizer('choice_self_translation', function (Options $options, $value) {
+            if (true === $value && $options['choice_translation_locale']) {
+                throw new LogicException('Cannot use the "choice_self_translation" and "choice_translation_locale" options at the same time. Remove one of them.');
+            }
+
+            return $value;
+        });
     }
 
     /**

src/Symfony/Component/Form/Tests/Extension/Core/Type/LanguageTypeTest.php

@@ -12,6 +12,7 @@
 namespace Symfony\Component\Form\Tests\Extension\Core\Type;
 
 use Symfony\Component\Form\ChoiceList\View\ChoiceView;
+use Symfony\Component\Form\Exception\LogicException;
 use Symfony\Component\Intl\Util\IntlTestHelper;
 
 class LanguageTypeTest extends BaseTypeTest
@@ -86,6 +87,52 @@ public function testChoiceTranslationLocaleAndAlpha3Option()
         $this->assertNotContainsEquals(new ChoiceView('my', 'my', 'бірманська'), $choices);
     }
 
+    /**
+     * @requires extension intl
+     */
+    public function testChoiceSelfTranslationOption()
+    {
+        $choices = $this->factory
+            ->create(static::TESTED_TYPE, null, [
+                'choice_self_translation' => true,
+            ])
+            ->createView()->vars['choices'];
+
+        $this->assertContainsEquals(new ChoiceView('cs', 'cs', 'čeština'), $choices);
+        $this->assertContainsEquals(new ChoiceView('es', 'es', 'español'), $choices);
+        $this->assertContainsEquals(new ChoiceView('fr', 'fr', 'français'), $choices);
+        $this->assertContainsEquals(new ChoiceView('ta', 'ta', 'தமிழ்'), $choices);
+        $this->assertContainsEquals(new ChoiceView('uk', 'uk', 'українська'), $choices);
+        $this->assertContainsEquals(new ChoiceView('yi', 'yi', 'ייִדיש'), $choices);
+        $this->assertContainsEquals(new ChoiceView('zh', 'zh', '中文'), $choices);
+    }
+
+    /**
+     * @requires extension intl
+     */
+    public function testChoiceSelfTranslationAndAlpha3Options()
+    {
+        $choices = $this->factory
+            ->create(static::TESTED_TYPE, null, [
+                'alpha3' => true,
+                'choice_self_translation' => true,
+            ])
+            ->createView()->vars['choices'];
+
+        $this->assertContainsEquals(new ChoiceView('spa', 'spa', 'español'), $choices, '', false, false);
+        $this->assertContainsEquals(new ChoiceView('yid', 'yid', 'ייִדיש'), $choices, '', false, false);
+    }
+
+    public function testSelfTranslationNotAllowedWithChoiceTranslation()
+    {
+        $this->expectException(LogicException::class);
+
+        $this->factory->create(static::TESTED_TYPE, null, [
+            'choice_translation_locale' => 'es',
+            'choice_self_translation' => true,
+        ]);
+    }
+
     public function testMultipleLanguagesIsNotIncluded()
     {
         $choices = $this->factory->create(static::TESTED_TYPE, 'language')