feature #28375 [Translator] Deprecated transChoice and moved it away from contracts (Nyholm, nicolas-grekas)

This PR was merged into the 4.2-dev branch.

Discussion
----------

[Translator] Deprecated transChoice and moved it away from contracts

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | yes
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | Issue: https://github.com/symfony/symfony-docs/issues/10264

This will address comment made here: https://github.com/symfony/symfony/pull/27399#pullrequestreview-151929117

This PR moves the `transChoice()` method away from Contracts and back to the component. I also reverted changes in the `IdentityTranslator`. I will still use the deprecated `MessageSelector` but this is not fine since `transChoice()` is also deprecated.

Commits
-------

dc5f3bfff7 Make trans + %count% parameter resolve plurals
d870a850bd [Translator] Deprecated transChoice and moved it away from contracts

UPGRADE-4.2.md

@@ -114,6 +114,7 @@ FrameworkBundle
    set the "APP_ENV" environment variable instead.
  * The `--no-debug` console option has been deprecated,
    set the "APP_DEBUG" environment variable to "0" instead.
+ * The `Templating\Helper\TranslatorHelper::transChoice()` method has been deprecated, use the `trans()` one instead with a `%count%` parameter.
 
 Messenger
 ---------
@@ -219,9 +220,15 @@ Translation
 -----------
 
  * The `TranslatorInterface` has been deprecated in favor of `Symfony\Contracts\Translation\TranslatorInterface`
+ * The `Translator::transChoice()` method has been deprecated in favor of using `Translator::trans()` with "%count%" as the parameter driving plurals
  * The `MessageSelector`, `Interval` and `PluralizationRules` classes have been deprecated, use `IdentityTranslator` instead
  * The `Translator::getFallbackLocales()` and `TranslationDataCollector::getFallbackLocales()` method have been marked as internal
 
+TwigBundle
+----------
+
+ * The `transchoice` tag and filter have been deprecated, use the `trans` ones instead with a `%count%` parameter.
+
 Validator
 ---------
 

UPGRADE-5.0.md

@@ -120,6 +120,7 @@ FrameworkBundle
    set the "APP_ENV" environment variable instead.
  * The `--no-debug` console option has been removed, 
    set the "APP_DEBUG" environment variable to "0" instead.
+ * The `Templating\Helper\TranslatorHelper::transChoice()` method has been removed, use the `trans()` one instead with a `%count%` parameter.
 
 HttpFoundation
 --------------
@@ -196,11 +197,13 @@ Translation
  * The `TranslatorInterface` has been removed in favor of `Symfony\Contracts\Translation\TranslatorInterface`
  * The `MessageSelector`, `Interval` and `PluralizationRules` classes have been removed, use `IdentityTranslator` instead
  * The `Translator::getFallbackLocales()` and `TranslationDataCollector::getFallbackLocales()` method are now internal
+ * The `Translator::transChoice()` method has been removed in favor of using `Translator::trans()` with "%count%" as the parameter driving plurals
 
 TwigBundle
 ----------
 
  * The default value (`false`) of the `twig.strict_variables` configuration option has been changed to `%kernel.debug%`.
+ * The `transchoice` tag and filter have been removed, use the `trans` ones instead with a `%count%` parameter.
 
 Validator
 --------

src/Symfony/Bridge/Twig/CHANGELOG.md

@@ -4,8 +4,9 @@ CHANGELOG
 4.2.0
 -----
 
-* add bundle name suggestion on wrongly overridden templates paths
+ * add bundle name suggestion on wrongly overridden templates paths
-* added `name` argument in `debug:twig` command and changed `filter` argument as `--filter` option
+ * added `name` argument in `debug:twig` command and changed `filter` argument as `--filter` option
+ * deprecated the `transchoice` tag and filter, use the `trans` ones instead with a `%count%` parameter
 
 4.1.0
 -----

src/Symfony/Bridge/Twig/Extension/TranslationExtension.php

@@ -16,6 +16,7 @@ use Symfony\Bridge\Twig\NodeVisitor\TranslationNodeVisitor;
 use Symfony\Bridge\Twig\TokenParser\TransChoiceTokenParser;
 use Symfony\Bridge\Twig\TokenParser\TransDefaultDomainTokenParser;
 use Symfony\Bridge\Twig\TokenParser\TransTokenParser;
+use Symfony\Component\Translation\TranslatorInterface as LegacyTranslatorInterface;
 use Symfony\Contracts\Translation\TranslatorInterface;
 use Symfony\Contracts\Translation\TranslatorTrait;
 use Twig\Extension\AbstractExtension;
@@ -27,6 +28,8 @@ use Twig\TwigFilter;
  * Provides integration of the Translation component with Twig.
  *
  * @author Fabien Potencier <fabien@symfony.com>
+ *
+ * @final since Symfony 4.2
  */
 class TranslationExtension extends AbstractExtension
 {
@@ -34,20 +37,30 @@ class TranslationExtension extends AbstractExtension
         getLocale as private;
         setLocale as private;
         trans as private doTrans;
-        transChoice as private doTransChoice;
     }
 
     private $translator;
     private $translationNodeVisitor;
 
-    public function __construct(TranslatorInterface $translator = null, NodeVisitorInterface $translationNodeVisitor = null)
+    /**
+     * @param TranslatorInterface|null $translator
+     */
+    public function __construct($translator = null, NodeVisitorInterface $translationNodeVisitor = null)
     {
+        if (null !== $translator && !$translator instanceof LegacyTranslatorInterface && !$translator instanceof TranslatorInterface) {
+            throw new \TypeError(sprintf('Argument 1 passed to %s() must be an instance of %s, %s given.', __METHOD__, TranslatorInterface::class, \is_object($translator) ? \get_class($translator) : \gettype($translator)));
+        }
         $this->translator = $translator;
         $this->translationNodeVisitor = $translationNodeVisitor;
     }
 
+    /**
+     * @deprecated since Symfony 4.2
+     */
     public function getTranslator()
     {
+        @trigger_error(sprintf('The "%s()" method is deprecated since Symfony 4.2.', __METHOD__), E_USER_DEPRECATED);
+
         return $this->translator;
     }
 
@@ -58,7 +71,7 @@ class TranslationExtension extends AbstractExtension
     {
         return array(
             new TwigFilter('trans', array($this, 'trans')),
-            new TwigFilter('transchoice', array($this, 'transchoice')),
+            new TwigFilter('transchoice', array($this, 'transchoice'), array('deprecated' => '4.2', 'alternative' => 'trans" with parameter "%count%')),
         );
     }
 
@@ -96,8 +109,11 @@ class TranslationExtension extends AbstractExtension
         return $this->translationNodeVisitor ?: $this->translationNodeVisitor = new TranslationNodeVisitor();
     }
 
-    public function trans($message, array $arguments = array(), $domain = null, $locale = null)
+    public function trans($message, array $arguments = array(), $domain = null, $locale = null, $count = null)
     {
+        if (null !== $count) {
+            $arguments['%count%'] = $count;
+        }
         if (null === $this->translator) {
             return $this->doTrans($message, $arguments, $domain, $locale);
         }
@@ -105,10 +121,16 @@ class TranslationExtension extends AbstractExtension
         return $this->translator->trans($message, $arguments, $domain, $locale);
     }
 
+    /**
+     * @deprecated since Symfony 4.2, use the trans() method instead with a %count% parameter
+     */
     public function transchoice($message, $count, array $arguments = array(), $domain = null, $locale = null)
     {
         if (null === $this->translator) {
-            return $this->doTransChoice($message, $count, array_merge(array('%count%' => $count), $arguments), $domain, $locale);
+            return $this->doTrans($message, array_merge(array('%count%' => $count), $arguments), $domain, $locale);
+        }
+        if ($this->translator instanceof TranslatorInterface) {
+            return $this->translator->trans($message, array_merge(array('%count%' => $count), $arguments), $domain, $locale);
         }
 
         return $this->translator->transChoice($message, $count, array_merge(array('%count%' => $count), $arguments), $domain, $locale);

src/Symfony/Bridge/Twig/Node/TransNode.php

@@ -60,19 +60,12 @@ class TransNode extends Node
         $method = !$this->hasNode('count') ? 'trans' : 'transChoice';
 
         $compiler
-            ->write('echo $this->env->getExtension(\'Symfony\Bridge\Twig\Extension\TranslationExtension\')->getTranslator()->'.$method.'(')
+            ->write('echo $this->env->getExtension(\'Symfony\Bridge\Twig\Extension\TranslationExtension\')->trans(')
             ->subcompile($msg)
         ;
 
         $compiler->raw(', ');
 
-        if ($this->hasNode('count')) {
-            $compiler
-                ->subcompile($this->getNode('count'))
-                ->raw(', ')
-            ;
-        }
-
         if (null !== $vars) {
             $compiler
                 ->raw('array_merge(')
@@ -98,7 +91,17 @@ class TransNode extends Node
                 ->raw(', ')
                 ->subcompile($this->getNode('locale'))
             ;
+        } elseif ($this->hasNode('count')) {
+            $compiler->raw(', null');
         }
+
+        if ($this->hasNode('count')) {
+            $compiler
+                ->raw(', ')
+                ->subcompile($this->getNode('count'))
+            ;
+        }
+
         $compiler->raw(");\n");
     }
 

src/Symfony/Bridge/Twig/Tests/Extension/TranslationExtensionTest.php

@@ -45,6 +45,15 @@ class TranslationExtensionTest extends TestCase
         $this->assertEquals($expected, $this->getTemplate($template)->render($variables));
     }
 
+    /**
+     * @group legacy
+     * @dataProvider getTransChoiceTests
+     */
+    public function testTransChoice($template, $expected, array $variables = array())
+    {
+        $this->testTrans($template, $expected, $variables);
+    }
+
     /**
      * @expectedException        \Twig\Error\SyntaxError
      * @expectedExceptionMessage Unexpected token. Twig was looking for the "with", "from", or "into" keyword in "index" at line 3.
@@ -64,6 +73,7 @@ class TranslationExtensionTest extends TestCase
     }
 
     /**
+     * @group legacy
      * @expectedException        \Twig\Error\SyntaxError
      * @expectedExceptionMessage A message inside a transchoice tag must be a simple text in "index" at line 2.
      */
@@ -87,6 +97,69 @@ class TranslationExtensionTest extends TestCase
 
             array('{% trans into "fr"%}Hello{% endtrans %}', 'Hello'),
 
+            // trans with count
+            array(
+                '{% trans from "messages" %}{0} There is no apples|{1} There is one apple|]1,Inf] There is %count% apples{% endtrans %}',
+                'There is no apples',
+                array('count' => 0),
+            ),
+            array(
+                '{% trans %}{0} There is no apples|{1} There is one apple|]1,Inf] There is %count% apples{% endtrans %}',
+                'There is 5 apples',
+                array('count' => 5),
+            ),
+            array(
+                '{% trans %}{0} There is no apples|{1} There is one apple|]1,Inf] There is %count% apples (%name%){% endtrans %}',
+                'There is 5 apples (Symfony)',
+                array('count' => 5, 'name' => 'Symfony'),
+            ),
+            array(
+                '{% trans with { \'%name%\': \'Symfony\' } %}{0} There is no apples|{1} There is one apple|]1,Inf] There is %count% apples (%name%){% endtrans %}',
+                'There is 5 apples (Symfony)',
+                array('count' => 5),
+            ),
+            array(
+                '{% trans into "fr"%}{0} There is no apples|{1} There is one apple|]1,Inf] There is %count% apples{% endtrans %}',
+                'There is no apples',
+                array('count' => 0),
+            ),
+            array(
+                '{% trans count 5 into "fr"%}{0} There is no apples|{1} There is one apple|]1,Inf] There is %count% apples{% endtrans %}',
+                'There is 5 apples',
+            ),
+
+            // trans filter
+            array('{{ "Hello"|trans }}', 'Hello'),
+            array('{{ name|trans }}', 'Symfony', array('name' => 'Symfony')),
+            array('{{ hello|trans({ \'%name%\': \'Symfony\' }) }}', 'Hello Symfony', array('hello' => 'Hello %name%')),
+            array('{% set vars = { \'%name%\': \'Symfony\' } %}{{ hello|trans(vars) }}', 'Hello Symfony', array('hello' => 'Hello %name%')),
+            array('{{ "Hello"|trans({}, "messages", "fr") }}', 'Hello'),
+
+            // trans filter with count
+            array('{{ "{0} There is no apples|{1} There is one apple|]1,Inf] There is %count% apples"|trans(count=count) }}', 'There is 5 apples', array('count' => 5)),
+            array('{{ text|trans(count=5, arguments={\'%name%\': \'Symfony\'}) }}', 'There is 5 apples (Symfony)', array('text' => '{0} There is no apples|{1} There is one apple|]1,Inf] There is %count% apples (%name%)')),
+            array('{{ "{0} There is no apples|{1} There is one apple|]1,Inf] There is %count% apples"|trans({}, "messages", "fr", count) }}', 'There is 5 apples', array('count' => 5)),
+        );
+    }
+
+    /**
+     * @group legacy
+     */
+    public function getTransChoiceTests()
+    {
+        return array(
+            // trans tag
+            array('{% trans %}Hello{% endtrans %}', 'Hello'),
+            array('{% trans %}%name%{% endtrans %}', 'Symfony', array('name' => 'Symfony')),
+
+            array('{% trans from elsewhere %}Hello{% endtrans %}', 'Hello'),
+
+            array('{% trans %}Hello %name%{% endtrans %}', 'Hello Symfony', array('name' => 'Symfony')),
+            array('{% trans with { \'%name%\': \'Symfony\' } %}Hello %name%{% endtrans %}', 'Hello Symfony'),
+            array('{% set vars = { \'%name%\': \'Symfony\' } %}{% trans with vars %}Hello %name%{% endtrans %}', 'Hello Symfony'),
+
+            array('{% trans into "fr"%}Hello{% endtrans %}', 'Hello'),
+
             // transchoice
             array(
                 '{% transchoice count from "messages" %}{0} There is no apples|{1} There is one apple|]1,Inf] There is %count% apples{% endtranschoice %}',
@@ -145,8 +218,8 @@ class TranslationExtensionTest extends TestCase
                     {%- trans from "custom" %}foo{% endtrans %}
                     {{- "foo"|trans }}
                     {{- "foo"|trans({}, "custom") }}
-                    {{- "foo"|transchoice(1) }}
+                    {{- "foo"|trans(count=1) }}
-                    {{- "foo"|transchoice(1, {}, "custom") }}
+                    {{- "foo"|trans({"%count%":1}, "custom") }}
                 {% endblock %}
             ',
 
@@ -174,12 +247,12 @@ class TranslationExtensionTest extends TestCase
 
                 {%- block content %}
                     {{- "foo"|trans(arguments = {}, domain = "custom") }}
-                    {{- "foo"|transchoice(count = 1) }}
+                    {{- "foo"|trans(count = 1) }}
-                    {{- "foo"|transchoice(count = 1, arguments = {}, domain = "custom") }}
+                    {{- "foo"|trans(count = 1, arguments = {}, domain = "custom") }}
                     {{- "foo"|trans({}, domain = "custom") }}
                     {{- "foo"|trans({}, "custom", locale = "fr") }}
-                    {{- "foo"|transchoice(1, arguments = {}, domain = "custom") }}
+                    {{- "foo"|trans(arguments = {"%count%":1}, domain = "custom") }}
-                    {{- "foo"|transchoice(1, {}, "custom", locale = "fr") }}
+                    {{- "foo"|trans({"%count%":1}, "custom", locale = "fr") }}
                 {% endblock %}
             ',
 

src/Symfony/Bridge/Twig/Tests/Node/TransNodeTest.php

@@ -34,7 +34,7 @@ class TransNodeTest extends TestCase
 
         $this->assertEquals(
             sprintf(
-                'echo $this->env->getExtension(\'Symfony\Bridge\Twig\Extension\TranslationExtension\')->getTranslator()->trans("trans %%var%%", array_merge(array("%%var%%" => %s), %s), "messages");',
+                'echo $this->env->getExtension(\'Symfony\Bridge\Twig\Extension\TranslationExtension\')->trans("trans %%var%%", array_merge(array("%%var%%" => %s), %s), "messages");',
                 $this->getVariableGetterWithoutStrictCheck('var'),
                 $this->getVariableGetterWithStrictCheck('foo')
              ),

src/Symfony/Bridge/Twig/Tests/Translation/TwigExtractorTest.php

@@ -50,15 +50,21 @@ class TwigExtractorTest extends TestCase
         }
     }
 
+    /**
+     * @group legacy
+     * @dataProvider getLegacyExtractData
+     */
+    public function testLegacyExtract($template, $messages)
+    {
+        $this->testExtract($template, $messages);
+    }
+
     public function getExtractData()
     {
         return array(
             array('{{ "new key" | trans() }}', array('new key' => 'messages')),
             array('{{ "new key" | trans() | upper }}', array('new key' => 'messages')),
             array('{{ "new key" | trans({}, "domain") }}', array('new key' => 'domain')),
-            array('{{ "new key" | transchoice(1) }}', array('new key' => 'messages')),
-            array('{{ "new key" | transchoice(1) | upper }}', array('new key' => 'messages')),
-            array('{{ "new key" | transchoice(1, {}, "domain") }}', array('new key' => 'domain')),
             array('{% trans %}new key{% endtrans %}', array('new key' => 'messages')),
             array('{% trans %}  new key  {% endtrans %}', array('new key' => 'messages')),
             array('{% trans from "domain" %}new key{% endtrans %}', array('new key' => 'domain')),
@@ -67,11 +73,27 @@ class TwigExtractorTest extends TestCase
 
             // make sure 'trans_default_domain' tag is supported
             array('{% trans_default_domain "domain" %}{{ "new key"|trans }}', array('new key' => 'domain')),
-            array('{% trans_default_domain "domain" %}{{ "new key"|transchoice }}', array('new key' => 'domain')),
             array('{% trans_default_domain "domain" %}{% trans %}new key{% endtrans %}', array('new key' => 'domain')),
 
             // make sure this works with twig's named arguments
             array('{{ "new key" | trans(domain="domain") }}', array('new key' => 'domain')),
+        );
+    }
+
+    /**
+     * @group legacy
+     */
+    public function getLegacyExtractData()
+    {
+        return array(
+            array('{{ "new key" | transchoice(1) }}', array('new key' => 'messages')),
+            array('{{ "new key" | transchoice(1) | upper }}', array('new key' => 'messages')),
+            array('{{ "new key" | transchoice(1, {}, "domain") }}', array('new key' => 'domain')),
+
+            // make sure 'trans_default_domain' tag is supported
+            array('{% trans_default_domain "domain" %}{{ "new key"|transchoice }}', array('new key' => 'domain')),
+
+            // make sure this works with twig's named arguments
             array('{{ "new key" | transchoice(domain="domain", count=1) }}', array('new key' => 'domain')),
         );
     }

src/Symfony/Bridge/Twig/TokenParser/TransChoiceTokenParser.php

@@ -23,6 +23,8 @@ use Twig\Token;
  * Token Parser for the 'transchoice' tag.
  *
  * @author Fabien Potencier <fabien@symfony.com>
+ *
+ * @deprecated since Symfony 4.2, use the "trans" tag with a "%count%" parameter instead
  */
 class TransChoiceTokenParser extends TransTokenParser
 {
@@ -38,6 +40,8 @@ class TransChoiceTokenParser extends TransTokenParser
         $lineno = $token->getLine();
         $stream = $this->parser->getStream();
 
+        @trigger_error(sprintf('The "transchoice" tag is deprecated since Symfony 4.2, use the "trans" one instead with a "%count%" parameter in %s line %d.', $stream->getSourceContext()->getName(), $lineno), E_USER_DEPRECATED);
+
         $vars = new ArrayExpression(array(), $lineno);
 
         $count = $this->parser->getExpressionParser()->parseExpression();

src/Symfony/Bridge/Twig/TokenParser/TransTokenParser.php

@@ -39,10 +39,17 @@ class TransTokenParser extends AbstractTokenParser
         $lineno = $token->getLine();
         $stream = $this->parser->getStream();
 
+        $count = null;
         $vars = new ArrayExpression(array(), $lineno);
         $domain = null;
         $locale = null;
         if (!$stream->test(Token::BLOCK_END_TYPE)) {
+            if ($stream->test('count')) {
+                // {% trans count 5 %}
+                $stream->next();
+                $count = $this->parser->getExpressionParser()->parseExpression();
+            }
+
             if ($stream->test('with')) {
                 // {% trans with vars %}
                 $stream->next();
@@ -74,7 +81,7 @@ class TransTokenParser extends AbstractTokenParser
 
         $stream->expect(Token::BLOCK_END_TYPE);
 
-        return new TransNode($body, $domain, null, $vars, $locale, $lineno, $this->getTag());
+        return new TransNode($body, $domain, $count, $vars, $locale, $lineno, $this->getTag());
     }
 
     public function decideTransFork($token)

src/Symfony/Bundle/FrameworkBundle/CHANGELOG.md

@@ -18,6 +18,7 @@ CHANGELOG
    the "APP_ENV" environment variable instead.
  * Deprecated the `--no-debug` console option, set the "APP_DEBUG" 
    environment variable to "0" instead.
+ * Deprecated the `Templating\Helper\TranslatorHelper::transChoice()` method, use the `trans()` one instead with a `%count%` parameter
 
 4.1.0
 -----

src/Symfony/Bundle/FrameworkBundle/Command/TranslationDebugCommand.php

@@ -26,6 +26,7 @@ use Symfony\Component\Translation\LoggingTranslator;
 use Symfony\Component\Translation\MessageCatalogue;
 use Symfony\Component\Translation\Reader\TranslationReaderInterface;
 use Symfony\Component\Translation\Translator;
+use Symfony\Component\Translation\TranslatorInterface as LegacyTranslatorInterface;
 use Symfony\Contracts\Translation\TranslatorInterface;
 
 /**
@@ -50,8 +51,14 @@ class TranslationDebugCommand extends Command
     private $defaultTransPath;
     private $defaultViewsPath;
 
-    public function __construct(TranslatorInterface $translator, TranslationReaderInterface $reader, ExtractorInterface $extractor, string $defaultTransPath = null, string $defaultViewsPath = null)
+    /**
+     * @param TranslatorInterface $translator
+     */
+    public function __construct($translator, TranslationReaderInterface $reader, ExtractorInterface $extractor, string $defaultTransPath = null, string $defaultViewsPath = null)
     {
+        if (!$translator instanceof LegacyTranslatorInterface && !$translator instanceof TranslatorInterface) {
+            throw new \TypeError(sprintf('Argument 1 passed to %s() must be an instance of %s, %s given.', __METHOD__, TranslatorInterface::class, \is_object($translator) ? \get_class($translator) : \gettype($translator)));
+        }
         parent::__construct();
 
         $this->translator = $translator;

src/Symfony/Bundle/FrameworkBundle/Templating/Helper/TranslatorHelper.php

@@ -12,6 +12,7 @@
 namespace Symfony\Bundle\FrameworkBundle\Templating\Helper;
 
 use Symfony\Component\Templating\Helper\Helper;
+use Symfony\Component\Translation\TranslatorInterface as LegacyTranslatorInterface;
 use Symfony\Contracts\Translation\TranslatorInterface;
 use Symfony\Contracts\Translation\TranslatorTrait;
 
@@ -24,13 +25,18 @@ class TranslatorHelper extends Helper
         getLocale as private;
         setLocale as private;
         trans as private doTrans;
-        transChoice as private doTransChoice;
     }
 
     protected $translator;
 
-    public function __construct(TranslatorInterface $translator = null)
+    /**
+     * @param TranslatorInterface|null $translator
+     */
+    public function __construct($translator = null)
     {
+        if (null !== $translator && !$translator instanceof LegacyTranslatorInterface && !$translator instanceof TranslatorInterface) {
+            throw new \TypeError(sprintf('Argument 1 passed to %s() must be an instance of %s, %s given.', __METHOD__, TranslatorInterface::class, \is_object($translator) ? \get_class($translator) : \gettype($translator)));
+        }
         $this->translator = $translator;
     }
 
@@ -48,11 +54,17 @@ class TranslatorHelper extends Helper
 
     /**
      * @see TranslatorInterface::transChoice()
+     * @deprecated since Symfony 4.2, use the trans() method instead with a %count% parameter
      */
     public function transChoice($id, $number, array $parameters = array(), $domain = 'messages', $locale = null)
     {
+        @trigger_error(sprintf('The "%s()" method is deprecated since Symfony 4.2, use the trans() one instead with a "%count%" parameter.', __METHOD__), E_USER_DEPRECATED);
+
         if (null === $this->translator) {
-            return $this->doTransChoice($id, $number, $parameters, $domain, $locale);
+            return $this->doTrans($id, array('%count%' => $number) + $parameters, $domain, $locale);
+        }
+        if ($this->translator instanceof TranslatorInterface) {
+            return $this->translator->trans($id, array('%count%' => $number) + $parameters, $domain, $locale);
         }
 
         return $this->translator->transChoice($id, $number, $parameters, $domain, $locale);

src/Symfony/Bundle/FrameworkBundle/Tests/Translation/TranslatorTest.php

@@ -52,14 +52,27 @@ class TranslatorTest extends TestCase
         $this->assertEquals('foo (FR)', $translator->trans('foo'));
         $this->assertEquals('bar (EN)', $translator->trans('bar'));
         $this->assertEquals('foobar (ES)', $translator->trans('foobar'));
-        $this->assertEquals('choice 0 (EN)', $translator->transChoice('choice', 0));
+        $this->assertEquals('choice 0 (EN)', $translator->trans('choice', array('%count%' => 0)));
         $this->assertEquals('no translation', $translator->trans('no translation'));
         $this->assertEquals('foobarfoo (PT-PT)', $translator->trans('foobarfoo'));
-        $this->assertEquals('other choice 1 (PT-BR)', $translator->transChoice('other choice', 1));
+        $this->assertEquals('other choice 1 (PT-BR)', $translator->trans('other choice', array('%count%' => 1)));
         $this->assertEquals('foobarbaz (fr.UTF-8)', $translator->trans('foobarbaz'));
         $this->assertEquals('foobarbax (sr@latin)', $translator->trans('foobarbax'));
     }
 
+    /**
+     * @group legacy
+     */
+    public function testTransChoiceWithoutCaching()
+    {
+        $translator = $this->getTranslator($this->getLoader());
+        $translator->setLocale('fr');
+        $translator->setFallbackLocales(array('en', 'es', 'pt-PT', 'pt_BR', 'fr.UTF-8', 'sr@latin'));
+
+        $this->assertEquals('choice 0 (EN)', $translator->transChoice('choice', 0));
+        $this->assertEquals('other choice 1 (PT-BR)', $translator->transChoice('other choice', 1));
+    }
+
     public function testTransWithCaching()
     {
         // prime the cache
@@ -70,10 +83,10 @@ class TranslatorTest extends TestCase
         $this->assertEquals('foo (FR)', $translator->trans('foo'));
         $this->assertEquals('bar (EN)', $translator->trans('bar'));
         $this->assertEquals('foobar (ES)', $translator->trans('foobar'));
-        $this->assertEquals('choice 0 (EN)', $translator->transChoice('choice', 0));
+        $this->assertEquals('choice 0 (EN)', $translator->trans('choice', array('%count%' => 0)));
         $this->assertEquals('no translation', $translator->trans('no translation'));
         $this->assertEquals('foobarfoo (PT-PT)', $translator->trans('foobarfoo'));
-        $this->assertEquals('other choice 1 (PT-BR)', $translator->transChoice('other choice', 1));
+        $this->assertEquals('other choice 1 (PT-BR)', $translator->trans('other choice', array('%count%' => 1)));
         $this->assertEquals('foobarbaz (fr.UTF-8)', $translator->trans('foobarbaz'));
         $this->assertEquals('foobarbax (sr@latin)', $translator->trans('foobarbax'));
 
@@ -88,14 +101,37 @@ class TranslatorTest extends TestCase
         $this->assertEquals('foo (FR)', $translator->trans('foo'));
         $this->assertEquals('bar (EN)', $translator->trans('bar'));
         $this->assertEquals('foobar (ES)', $translator->trans('foobar'));
-        $this->assertEquals('choice 0 (EN)', $translator->transChoice('choice', 0));
         $this->assertEquals('no translation', $translator->trans('no translation'));
         $this->assertEquals('foobarfoo (PT-PT)', $translator->trans('foobarfoo'));
-        $this->assertEquals('other choice 1 (PT-BR)', $translator->transChoice('other choice', 1));
         $this->assertEquals('foobarbaz (fr.UTF-8)', $translator->trans('foobarbaz'));
         $this->assertEquals('foobarbax (sr@latin)', $translator->trans('foobarbax'));
     }
 
+    /**
+     * @group legacy
+     */
+    public function testTransChoiceWithCaching()
+    {
+        // prime the cache
+        $translator = $this->getTranslator($this->getLoader(), array('cache_dir' => $this->tmpDir));
+        $translator->setLocale('fr');
+        $translator->setFallbackLocales(array('en', 'es', 'pt-PT', 'pt_BR', 'fr.UTF-8', 'sr@latin'));
+
+        $this->assertEquals('choice 0 (EN)', $translator->transChoice('choice', 0));
+        $this->assertEquals('other choice 1 (PT-BR)', $translator->transChoice('other choice', 1));
+
+        // do it another time as the cache is primed now
+        $loader = $this->getMockBuilder('Symfony\Component\Translation\Loader\LoaderInterface')->getMock();
+        $loader->expects($this->never())->method('load');
+
+        $translator = $this->getTranslator($loader, array('cache_dir' => $this->tmpDir));
+        $translator->setLocale('fr');
+        $translator->setFallbackLocales(array('en', 'es', 'pt-PT', 'pt_BR', 'fr.UTF-8', 'sr@latin'));
+
+        $this->assertEquals('choice 0 (EN)', $translator->transChoice('choice', 0));
+        $this->assertEquals('other choice 1 (PT-BR)', $translator->transChoice('other choice', 1));
+    }
+
     /**
      * @expectedException \InvalidArgumentException
      * @expectedExceptionMessage Invalid "invalid locale" locale.

src/Symfony/Component/Form/Extension/Csrf/CsrfExtension.php

@@ -13,6 +13,7 @@ namespace Symfony\Component\Form\Extension\Csrf;
 
 use Symfony\Component\Form\AbstractExtension;
 use Symfony\Component\Security\Csrf\CsrfTokenManagerInterface;
+use Symfony\Component\Translation\TranslatorInterface as LegacyTranslatorInterface;
 use Symfony\Contracts\Translation\TranslatorInterface;
 
 /**
@@ -28,11 +29,14 @@ class CsrfExtension extends AbstractExtension
 
     /**
      * @param CsrfTokenManagerInterface $tokenManager      The CSRF token manager
-     * @param TranslatorInterface       $translator        The translator for translating error messages
+     * @param TranslatorInterface|null  $translator        The translator for translating error messages
      * @param string|null               $translationDomain The translation domain for translating
      */
-    public function __construct(CsrfTokenManagerInterface $tokenManager, TranslatorInterface $translator = null, string $translationDomain = null)
+    public function __construct(CsrfTokenManagerInterface $tokenManager, $translator = null, string $translationDomain = null)
     {
+        if (null !== $translator && !$translator instanceof LegacyTranslatorInterface && !$translator instanceof TranslatorInterface) {
+            throw new \TypeError(sprintf('Argument 2 passed to %s() must be an instance of %s, %s given.', __METHOD__, TranslatorInterface::class, \is_object($translator) ? \get_class($translator) : \gettype($translator)));
+        }
         $this->tokenManager = $tokenManager;
         $this->translator = $translator;
         $this->translationDomain = $translationDomain;

src/Symfony/Component/Form/Extension/Csrf/EventListener/CsrfValidationListener.php

@@ -18,6 +18,7 @@ use Symfony\Component\Form\FormEvents;
 use Symfony\Component\Form\Util\ServerParams;
 use Symfony\Component\Security\Csrf\CsrfToken;
 use Symfony\Component\Security\Csrf\CsrfTokenManagerInterface;
+use Symfony\Component\Translation\TranslatorInterface as LegacyTranslatorInterface;
 use Symfony\Contracts\Translation\TranslatorInterface;
 
 /**
@@ -40,8 +41,14 @@ class CsrfValidationListener implements EventSubscriberInterface
         );
     }
 
-    public function __construct(string $fieldName, CsrfTokenManagerInterface $tokenManager, string $tokenId, string $errorMessage, TranslatorInterface $translator = null, string $translationDomain = null, ServerParams $serverParams = null)
+    /**
+     * @param TranslatorInterface|null $translator
+     */
+    public function __construct(string $fieldName, CsrfTokenManagerInterface $tokenManager, string $tokenId, string $errorMessage, $translator = null, string $translationDomain = null, ServerParams $serverParams = null)
     {
+        if (null !== $translator && !$translator instanceof LegacyTranslatorInterface && !$translator instanceof TranslatorInterface) {
+            throw new \TypeError(sprintf('Argument 5 passed to %s() must be an instance of %s, %s given.', __METHOD__, TranslatorInterface::class, \is_object($translator) ? \get_class($translator) : \gettype($translator)));
+        }
         $this->fieldName = $fieldName;
         $this->tokenManager = $tokenManager;
         $this->tokenId = $tokenId;

src/Symfony/Component/Form/Extension/Csrf/Type/FormTypeCsrfExtension.php

@@ -19,6 +19,7 @@ use Symfony\Component\Form\FormView;
 use Symfony\Component\Form\Util\ServerParams;
 use Symfony\Component\OptionsResolver\OptionsResolver;
 use Symfony\Component\Security\Csrf\CsrfTokenManagerInterface;
+use Symfony\Component\Translation\TranslatorInterface as LegacyTranslatorInterface;
 use Symfony\Contracts\Translation\TranslatorInterface;
 
 /**
@@ -33,8 +34,14 @@ class FormTypeCsrfExtension extends AbstractTypeExtension
     private $translationDomain;
     private $serverParams;
 
-    public function __construct(CsrfTokenManagerInterface $defaultTokenManager, bool $defaultEnabled = true, string $defaultFieldName = '_token', TranslatorInterface $translator = null, string $translationDomain = null, ServerParams $serverParams = null)
+    /**
+     * @param TranslatorInterface|null $translator
+     */
+    public function __construct(CsrfTokenManagerInterface $defaultTokenManager, bool $defaultEnabled = true, string $defaultFieldName = '_token', $translator = null, string $translationDomain = null, ServerParams $serverParams = null)
     {
+        if (null !== $translator && !$translator instanceof LegacyTranslatorInterface && !$translator instanceof TranslatorInterface) {
+            throw new \TypeError(sprintf('Argument 4 passed to %s() must be an instance of %s, %s given.', __METHOD__, TranslatorInterface::class, \is_object($translator) ? \get_class($translator) : \gettype($translator)));
+        }
         $this->defaultTokenManager = $defaultTokenManager;
         $this->defaultEnabled = $defaultEnabled;
         $this->defaultFieldName = $defaultFieldName;

src/Symfony/Component/Form/Extension/Validator/Type/UploadValidatorExtension.php

@@ -14,6 +14,7 @@ namespace Symfony\Component\Form\Extension\Validator\Type;
 use Symfony\Component\Form\AbstractTypeExtension;
 use Symfony\Component\OptionsResolver\Options;
 use Symfony\Component\OptionsResolver\OptionsResolver;
+use Symfony\Component\Translation\TranslatorInterface as LegacyTranslatorInterface;
 use Symfony\Contracts\Translation\TranslatorInterface;
 
 /**
@@ -25,8 +26,14 @@ class UploadValidatorExtension extends AbstractTypeExtension
     private $translator;
     private $translationDomain;
 
-    public function __construct(TranslatorInterface $translator, string $translationDomain = null)
+    /**
+     * @param TranslatorInterface $translator
+     */
+    public function __construct($translator, string $translationDomain = null)
     {
+        if (!$translator instanceof LegacyTranslatorInterface && !$translator instanceof TranslatorInterface) {
+            throw new \TypeError(sprintf('Argument 1 passed to %s() must be an instance of %s, %s given.', __METHOD__, TranslatorInterface::class, \is_object($translator) ? \get_class($translator) : \gettype($translator)));
+        }
         $this->translator = $translator;
         $this->translationDomain = $translationDomain;
     }

src/Symfony/Component/HttpKernel/EventListener/TranslatorListener.php

@@ -17,6 +17,7 @@ use Symfony\Component\HttpFoundation\RequestStack;
 use Symfony\Component\HttpKernel\Event\FinishRequestEvent;
 use Symfony\Component\HttpKernel\Event\GetResponseEvent;
 use Symfony\Component\HttpKernel\KernelEvents;
+use Symfony\Component\Translation\TranslatorInterface as LegacyTranslatorInterface;
 use Symfony\Contracts\Translation\TranslatorInterface;
 
 /**
@@ -29,8 +30,14 @@ class TranslatorListener implements EventSubscriberInterface
     private $translator;
     private $requestStack;
 
-    public function __construct(TranslatorInterface $translator, RequestStack $requestStack)
+    /**
+     * @param TranslatorInterface $translator
+     */
+    public function __construct($translator, RequestStack $requestStack)
     {
+        if (!$translator instanceof LegacyTranslatorInterface && !$translator instanceof TranslatorInterface) {
+            throw new \TypeError(sprintf('Argument 1 passed to %s() must be an instance of %s, %s given.', __METHOD__, TranslatorInterface::class, \is_object($translator) ? \get_class($translator) : \gettype($translator)));
+        }
         $this->translator = $translator;
         $this->requestStack = $requestStack;
     }

src/Symfony/Component/Translation/CHANGELOG.md

@@ -5,6 +5,7 @@ CHANGELOG
 -----
 
  * Started using ICU parent locales as fallback locales.
+ * deprecated `Translator::transChoice()` in favor of using `Translator::trans()` with a `%count%` parameter
  * deprecated `TranslatorInterface` in favor of `Symfony\Contracts\Translation\TranslatorInterface`
  * deprecated `MessageSelector`, `Interval` and `PluralizationRules`; use `IdentityTranslator` instead
  * Added `IntlMessageFormatter` and `FallbackMessageFormatter`

src/Symfony/Component/Translation/DataCollectorTranslator.php

@@ -18,7 +18,7 @@ use Symfony\Contracts\Translation\TranslatorInterface;
 /**
  * @author Abdellatif Ait boudad <a.aitboudad@gmail.com>
  */
-class DataCollectorTranslator implements LegacyTranslatorInterface, TranslatorBagInterface
+class DataCollectorTranslator implements LegacyTranslatorInterface, TranslatorInterface, TranslatorBagInterface
 {
     const MESSAGE_DEFINED = 0;
     const MESSAGE_MISSING = 1;
@@ -34,8 +34,11 @@ class DataCollectorTranslator implements LegacyTranslatorInterface, TranslatorBa
     /**
      * @param TranslatorInterface $translator The translator must implement TranslatorBagInterface
      */
-    public function __construct(TranslatorInterface $translator)
+    public function __construct($translator)
     {
+        if (!$translator instanceof LegacyTranslatorInterface && !$translator instanceof TranslatorInterface) {
+            throw new \TypeError(sprintf('Argument 1 passed to %s() must be an instance of %s, %s given.', __METHOD__, TranslatorInterface::class, \is_object($translator) ? \get_class($translator) : \gettype($translator)));
+        }
         if (!$translator instanceof TranslatorBagInterface) {
             throw new InvalidArgumentException(sprintf('The Translator "%s" must implement TranslatorInterface and TranslatorBagInterface.', \get_class($translator)));
         }
@@ -56,11 +59,18 @@ class DataCollectorTranslator implements LegacyTranslatorInterface, TranslatorBa
 
     /**
      * {@inheritdoc}
+     *
+     * @deprecated since Symfony 4.2, use the trans() method instead with a %count% parameter
      */
     public function transChoice($id, $number, array $parameters = array(), $domain = null, $locale = null)
     {
+        if ($this->translator instanceof TranslatorInterface) {
+            $trans = $this->translator->trans($id, array('%count%' => $number) + $parameters, $domain, $locale);
+        }
+
         $trans = $this->translator->transChoice($id, $number, $parameters, $domain, $locale);
-        $this->collectMessage($locale, $domain, $id, $trans, $parameters, $number);
+
+        $this->collectMessage($locale, $domain, $id, $trans, array('%count%' => $number) + $parameters);
 
         return $trans;
     }
@@ -125,9 +135,8 @@ class DataCollectorTranslator implements LegacyTranslatorInterface, TranslatorBa
      * @param string      $id
      * @param string      $translation
      * @param array|null  $parameters
-     * @param int|null    $number
      */
-    private function collectMessage($locale, $domain, $id, $translation, $parameters = array(), $number = null)
+    private function collectMessage($locale, $domain, $id, $translation, $parameters = array())
     {
         if (null === $domain) {
             $domain = 'messages';
@@ -160,8 +169,8 @@ class DataCollectorTranslator implements LegacyTranslatorInterface, TranslatorBa
             'id' => $id,
             'translation' => $translation,
             'parameters' => $parameters,
-            'transChoiceNumber' => $number,
             'state' => $state,
+            'transChoiceNumber' => isset($parameters['%count%']) && is_numeric($parameters['%count%']) ? $parameters['%count%'] : null,
         );
     }
 }

src/Symfony/Component/Translation/Formatter/ChoiceMessageFormatterInterface.php

@@ -13,6 +13,8 @@ namespace Symfony\Component\Translation\Formatter;
 
 /**
  * @author Abdellatif Ait boudad <a.aitboudad@gmail.com>
+ *
+ * @deprecated since Symfony 4.2, use MessageFormatterInterface::format() with a %count% parameter instead
  */
 interface ChoiceMessageFormatterInterface
 {

src/Symfony/Component/Translation/Formatter/MessageFormatter.php

@@ -13,6 +13,7 @@ namespace Symfony\Component\Translation\Formatter;
 
 use Symfony\Component\Translation\IdentityTranslator;
 use Symfony\Component\Translation\MessageSelector;
+use Symfony\Component\Translation\TranslatorInterface as LegacyTranslatorInterface;
 use Symfony\Contracts\Translation\TranslatorInterface;
 
 /**
@@ -29,7 +30,7 @@ class MessageFormatter implements MessageFormatterInterface, ChoiceMessageFormat
     {
         if ($translator instanceof MessageSelector) {
             $translator = new IdentityTranslator($translator);
-        } elseif (null !== $translator && !$translator instanceof TranslatorInterface) {
+        } elseif (null !== $translator && !$translator instanceof TranslatorInterface && !$translator instanceof LegacyTranslatorInterface) {
             throw new \TypeError(sprintf('Argument 1 passed to %s() must be an instance of %s, %s given.', __METHOD__, TranslatorInterface::class, \is_object($translator) ? \get_class($translator) : \gettype($translator)));
         }
 
@@ -41,15 +42,27 @@ class MessageFormatter implements MessageFormatterInterface, ChoiceMessageFormat
      */
     public function format($message, $locale, array $parameters = array())
     {
+        if ($this->translator instanceof TranslatorInterface) {
+            return $this->translator->trans($message, $parameters, null, $locale);
+        }
+
         return strtr($message, $parameters);
     }
 
     /**
      * {@inheritdoc}
+     *
+     * @deprecated since Symfony 4.2, use format() with a %count% parameter instead
      */
     public function choiceFormat($message, $number, $locale, array $parameters = array())
     {
-        $parameters = array_merge(array('%count%' => $number), $parameters);
+        @trigger_error(sprintf('The "%s()" method is deprecated since Symfony 4.2, use the format() one instead with a %count% parameter.', __METHOD__), E_USER_DEPRECATED);
+
+        $parameters = array('%count%' => $number) + $parameters;
+
+        if ($this->translator instanceof TranslatorInterface) {
+            return $this->format($message, $locale, $parameters);
+        }
 
         return $this->format($this->translator->transChoice($message, $number, array(), null, $locale), $locale, $parameters);
     }

src/Symfony/Component/Translation/IdentityTranslator.php

@@ -11,6 +11,8 @@
 
 namespace Symfony\Component\Translation;
 
+use Symfony\Component\Translation\TranslatorInterface as LegacyTranslatorInterface;
+use Symfony\Contracts\Translation\TranslatorInterface;
 use Symfony\Contracts\Translation\TranslatorTrait;
 
 /**
@@ -18,11 +20,9 @@ use Symfony\Contracts\Translation\TranslatorTrait;
  *
  * @author Fabien Potencier <fabien@symfony.com>
  */
-class IdentityTranslator implements TranslatorInterface
+class IdentityTranslator implements LegacyTranslatorInterface, TranslatorInterface
 {
-    use TranslatorTrait {
+    use TranslatorTrait;
-        transChoice as private doTransChoice;
-    }
 
     private $selector;
 
@@ -40,14 +40,18 @@ class IdentityTranslator implements TranslatorInterface
 
     /**
      * {@inheritdoc}
+     *
+     * @deprecated since Symfony 4.2, use the trans() method instead with a %count% parameter
      */
     public function transChoice($id, $number, array $parameters = array(), $domain = null, $locale = null)
     {
+        @trigger_error(sprintf('The "%s()" method is deprecated since Symfony 4.2, use the trans() one instead with a "%count%" parameter.', __METHOD__), E_USER_DEPRECATED);
+
         if ($this->selector) {
-            return strtr($this->selector->choose((string) $id, (int) $number, $locale ?: $this->getLocale()), $parameters);
+            return strtr($this->selector->choose((string) $id, $number, $locale ?: $this->getLocale()), $parameters);
         }
 
-        return $this->doTransChoice($id, $number, $parameters, $domain, $locale);
+        return $this->trans($id, array('%count%' => $number) + $parameters, $domain, $locale);
     }
 
     private function getPluralizationRule(int $number, string $locale): int

src/Symfony/Component/Translation/LoggingTranslator.php

@@ -32,8 +32,11 @@ class LoggingTranslator implements LegacyTranslatorInterface, TranslatorBagInter
      * @param TranslatorInterface $translator The translator must implement TranslatorBagInterface
      * @param LoggerInterface     $logger
      */
-    public function __construct(TranslatorInterface $translator, LoggerInterface $logger)
+    public function __construct($translator, LoggerInterface $logger)
     {
+        if (!$translator instanceof LegacyTranslatorInterface && !$translator instanceof TranslatorInterface) {
+            throw new \TypeError(sprintf('Argument 1 passed to %s() must be an instance of %s, %s given.', __METHOD__, TranslatorInterface::class, \is_object($translator) ? \get_class($translator) : \gettype($translator)));
+        }
         if (!$translator instanceof TranslatorBagInterface) {
             throw new InvalidArgumentException(sprintf('The Translator "%s" must implement TranslatorInterface and TranslatorBagInterface.', \get_class($translator)));
         }
@@ -55,10 +58,19 @@ class LoggingTranslator implements LegacyTranslatorInterface, TranslatorBagInter
 
     /**
      * {@inheritdoc}
+     *
+     * @deprecated since Symfony 4.2, use the trans() method instead with a %count% parameter
      */
     public function transChoice($id, $number, array $parameters = array(), $domain = null, $locale = null)
     {
-        $trans = $this->translator->transChoice($id, $number, $parameters, $domain, $locale);
+        @trigger_error(sprintf('The "%s()" method is deprecated since Symfony 4.2, use the trans() one instead with a "%count%" parameter.', __METHOD__), E_USER_DEPRECATED);
+
+        if ($this->translator instanceof TranslatorInterface) {
+            $trans = $this->translator->trans($id, array('%count%' => $number) + $parameters, $domain, $locale);
+        } else {
+            $trans = $this->translator->transChoice($id, $number, $parameters, $domain, $locale);
+        }
+
         $this->log($id, $domain, $locale);
 
         return $trans;

src/Symfony/Component/Translation/MessageSelector.php

@@ -43,9 +43,9 @@ class MessageSelector
      * The two methods can also be mixed:
      *     {0} There are no apples|one: There is one apple|more: There are %count% apples
      *
-     * @param string $message The message being translated
+     * @param string    $message The message being translated
-     * @param int    $number  The number of items represented for the message
+     * @param int|float $number  The number of items represented for the message
-     * @param string $locale  The locale to use for choosing
+     * @param string    $locale  The locale to use for choosing
      *
      * @return string
      *

src/Symfony/Component/Translation/Tests/DataCollectorTranslatorTest.php

@@ -25,7 +25,7 @@ class DataCollectorTranslatorTest extends TestCase
 
         $collector->trans('foo');
         $collector->trans('bar');
-        $collector->transChoice('choice', 0);
+        $collector->trans('choice', array('%count%' => 0));
         $collector->trans('bar_ru');
         $collector->trans('bar_ru', array('foo' => 'bar'));
 
@@ -54,7 +54,7 @@ class DataCollectorTranslatorTest extends TestCase
             'locale' => 'en',
             'domain' => 'messages',
             'state' => DataCollectorTranslator::MESSAGE_MISSING,
-            'parameters' => array(),
+            'parameters' => array('%count%' => 0),
             'transChoiceNumber' => 0,
         );
         $expectedMessages[] = array(
@@ -79,6 +79,30 @@ class DataCollectorTranslatorTest extends TestCase
         $this->assertEquals($expectedMessages, $collector->getCollectedMessages());
     }
 
+    /**
+     * @group legacy
+     */
+    public function testCollectMessagesTransChoice()
+    {
+        $collector = $this->createCollector();
+        $collector->setFallbackLocales(array('fr', 'ru'));
+        $collector->transChoice('choice', 0);
+
+        $expectedMessages = array();
+
+        $expectedMessages[] = array(
+              'id' => 'choice',
+              'translation' => 'choice',
+              'locale' => 'en',
+              'domain' => 'messages',
+              'state' => DataCollectorTranslator::MESSAGE_MISSING,
+              'parameters' => array('%count%' => 0),
+              'transChoiceNumber' => 0,
+        );
+
+        $this->assertEquals($expectedMessages, $collector->getCollectedMessages());
+    }
+
     private function createCollector()
     {
         $translator = new Translator('en');

src/Symfony/Component/Translation/Tests/Formatter/MessageFormatterTest.php

@@ -26,6 +26,7 @@ class MessageFormatterTest extends TestCase
 
     /**
      * @dataProvider getTransChoiceMessages
+     * @group legacy
      */
     public function testFormatPlural($expected, $message, $number, $parameters)
     {

src/Symfony/Component/Translation/Tests/LoggingTranslatorTest.php

@@ -21,17 +21,19 @@ class LoggingTranslatorTest extends TestCase
     public function testTransWithNoTranslationIsLogged()
     {
         $logger = $this->getMockBuilder('Psr\Log\LoggerInterface')->getMock();
-        $logger->expects($this->exactly(2))
+        $logger->expects($this->exactly(1))
             ->method('warning')
             ->with('Translation not found.')
         ;
 
         $translator = new Translator('ar');
         $loggableTranslator = new LoggingTranslator($translator, $logger);
-        $loggableTranslator->transChoice('some_message2', 10, array('%count%' => 10));
         $loggableTranslator->trans('bar');
     }
 
+    /**
+     * @group legacy
+     */
     public function testTransChoiceFallbackIsLogged()
     {
         $logger = $this->getMockBuilder('Psr\Log\LoggerInterface')->getMock();
@@ -47,4 +49,20 @@ class LoggingTranslatorTest extends TestCase
         $loggableTranslator = new LoggingTranslator($translator, $logger);
         $loggableTranslator->transChoice('some_message2', 10, array('%count%' => 10));
     }
+
+    /**
+     * @group legacy
+     */
+    public function testTransChoiceWithNoTranslationIsLogged()
+    {
+        $logger = $this->getMockBuilder('Psr\Log\LoggerInterface')->getMock();
+        $logger->expects($this->exactly(1))
+            ->method('warning')
+            ->with('Translation not found.')
+        ;
+
+        $translator = new Translator('ar');
+        $loggableTranslator = new LoggingTranslator($translator, $logger);
+        $loggableTranslator->transChoice('some_message2', 10, array('%count%' => 10));
+    }
 }

src/Symfony/Component/Translation/Tests/TranslatorTest.php

@@ -393,6 +393,7 @@ class TranslatorTest extends TestCase
 
     /**
      * @dataProvider getTransChoiceTests
+     * @group legacy
      */
     public function testTransChoice($expected, $id, $translation, $number, $parameters, $locale, $domain)
     {
@@ -406,6 +407,7 @@ class TranslatorTest extends TestCase
     /**
      * @dataProvider      getInvalidLocalesTests
      * @expectedException \Symfony\Component\Translation\Exception\InvalidArgumentException
+     * @group legacy
      */
     public function testTransChoiceInvalidLocale($locale)
     {
@@ -418,6 +420,7 @@ class TranslatorTest extends TestCase
 
     /**
      * @dataProvider      getValidLocalesTests
+     * @group legacy
      */
     public function testTransChoiceValidLocale($locale)
     {
@@ -499,7 +502,7 @@ class TranslatorTest extends TestCase
             array('Il y a 0 pomme', new StringClass('{0} There are no appless|{1} There is one apple|]1,Inf] There is %count% apples'), '[0,1] Il y a %count% pomme|]1,Inf] Il y a %count% pommes', 0, array(), 'fr', ''),
 
             // Override %count% with a custom value
-            array('Il y a quelques pommes', 'one: There is one apple|more: There are %count% apples', 'one: Il y a %count% pomme|more: Il y a %count% pommes', 2, array('%count%' => 'quelques'), 'fr', ''),
+            array('Il y a quelques pommes', 'one: There is one apple|more: There are %count% apples', 'one: Il y a %count% pomme|more: Il y a quelques pommes', 2, array('%count%' => 'quelques'), 'fr', ''),
         );
     }
 
@@ -537,6 +540,9 @@ class TranslatorTest extends TestCase
         );
     }
 
+    /**
+     * @group legacy
+     */
     public function testTransChoiceFallback()
     {
         $translator = new Translator('ru');
@@ -547,6 +553,9 @@ class TranslatorTest extends TestCase
         $this->assertEquals('10 things', $translator->transChoice('some_message2', 10, array('%count%' => 10)));
     }
 
+    /**
+     * @group legacy
+     */
     public function testTransChoiceFallbackBis()
     {
         $translator = new Translator('ru');
@@ -557,6 +566,9 @@ class TranslatorTest extends TestCase
         $this->assertEquals('10 things', $translator->transChoice('some_message2', 10, array('%count%' => 10)));
     }
 
+    /**
+     * @group legacy
+     */
     public function testTransChoiceFallbackWithNoTranslation()
     {
         $translator = new Translator('ru');

src/Symfony/Component/Translation/Translator.php

@@ -22,11 +22,13 @@ use Symfony\Component\Translation\Formatter\ChoiceMessageFormatterInterface;
 use Symfony\Component\Translation\Formatter\MessageFormatter;
 use Symfony\Component\Translation\Formatter\MessageFormatterInterface;
 use Symfony\Component\Translation\Loader\LoaderInterface;
+use Symfony\Component\Translation\TranslatorInterface as LegacyTranslatorInterface;
+use Symfony\Contracts\Translation\TranslatorInterface;
 
 /**
  * @author Fabien Potencier <fabien@symfony.com>
  */
-class Translator implements TranslatorInterface, TranslatorBagInterface
+class Translator implements LegacyTranslatorInterface, TranslatorInterface, TranslatorBagInterface
 {
     /**
      * @var MessageCatalogueInterface[]
@@ -199,9 +201,13 @@ class Translator implements TranslatorInterface, TranslatorBagInterface
 
     /**
      * {@inheritdoc}
+     *
+     * @deprecated since Symfony 4.2, use the trans() method instead with a %count% parameter
      */
     public function transChoice($id, $number, array $parameters = array(), $domain = null, $locale = null)
     {
+        @trigger_error(sprintf('The "%s()" method is deprecated since Symfony 4.2, use the trans() one instead with a "%count%" parameter.', __METHOD__), E_USER_DEPRECATED);
+
         if (!$this->formatter instanceof ChoiceMessageFormatterInterface) {
             throw new LogicException(sprintf('The formatter "%s" does not support plural translations.', \get_class($this->formatter)));
         }

src/Symfony/Component/Translation/TranslatorInterface.php

@@ -11,13 +11,59 @@
 
 namespace Symfony\Component\Translation;
 
-use Symfony\Contracts\Translation\TranslatorInterface as BaseTranslatorInterface;
+use Symfony\Component\Translation\Exception\InvalidArgumentException;
 
 /**
+ * TranslatorInterface.
+ *
  * @author Fabien Potencier <fabien@symfony.com>
  *
- * @deprecated since Symfony 4.2, use the same interface from the Symfony\Contracts\Translation namespace
+ * @deprecated since Symfony 4.2, use Symfony\Contracts\Translation\TranslatorInterface instead
  */
-interface TranslatorInterface extends BaseTranslatorInterface
+interface TranslatorInterface
 {
+    /**
+     * Translates the given message.
+     *
+     * @param string      $id         The message id (may also be an object that can be cast to string)
+     * @param array       $parameters An array of parameters for the message
+     * @param string|null $domain     The domain for the message or null to use the default
+     * @param string|null $locale     The locale or null to use the default
+     *
+     * @return string The translated string
+     *
+     * @throws InvalidArgumentException If the locale contains invalid characters
+     */
+    public function trans($id, array $parameters = array(), $domain = null, $locale = null);
+
+    /**
+     * Translates the given choice message by choosing a translation according to a number.
+     *
+     * @param string      $id         The message id (may also be an object that can be cast to string)
+     * @param int         $number     The number to use to find the indice of the message
+     * @param array       $parameters An array of parameters for the message
+     * @param string|null $domain     The domain for the message or null to use the default
+     * @param string|null $locale     The locale or null to use the default
+     *
+     * @return string The translated string
+     *
+     * @throws InvalidArgumentException If the locale contains invalid characters
+     */
+    public function transChoice($id, $number, array $parameters = array(), $domain = null, $locale = null);
+
+    /**
+     * Sets the current locale.
+     *
+     * @param string $locale The locale
+     *
+     * @throws InvalidArgumentException If the locale contains invalid characters
+     */
+    public function setLocale($locale);
+
+    /**
+     * Returns the current locale.
+     *
+     * @return string The locale
+     */
+    public function getLocale();
 }

src/Symfony/Component/Validator/Context/ExecutionContext.php

@@ -11,6 +11,7 @@
 
 namespace Symfony\Component\Validator\Context;
 
+use Symfony\Component\Translation\TranslatorInterface as LegacyTranslatorInterface;
 use Symfony\Component\Validator\Constraint;
 use Symfony\Component\Validator\ConstraintViolation;
 use Symfony\Component\Validator\ConstraintViolationList;
@@ -140,8 +141,11 @@ class ExecutionContext implements ExecutionContextInterface
      * @internal Called by {@link ExecutionContextFactory}. Should not be used
      *           in user code.
      */
-    public function __construct(ValidatorInterface $validator, $root, TranslatorInterface $translator, string $translationDomain = null)
+    public function __construct(ValidatorInterface $validator, $root, $translator, string $translationDomain = null)
     {
+        if (!$translator instanceof LegacyTranslatorInterface && !$translator instanceof TranslatorInterface) {
+            throw new \TypeError(sprintf('Argument 3 passed to %s() must be an instance of %s, %s given.', __METHOD__, TranslatorInterface::class, \is_object($translator) ? \get_class($translator) : \gettype($translator)));
+        }
         $this->validator = $validator;
         $this->root = $root;
         $this->translator = $translator;

src/Symfony/Component/Validator/Context/ExecutionContextFactory.php

@@ -11,6 +11,7 @@
 
 namespace Symfony\Component\Validator\Context;
 
+use Symfony\Component\Translation\TranslatorInterface as LegacyTranslatorInterface;
 use Symfony\Component\Validator\Validator\ValidatorInterface;
 use Symfony\Contracts\Translation\TranslatorInterface;
 
@@ -34,8 +35,12 @@ class ExecutionContextFactory implements ExecutionContextFactoryInterface
      *                                               use for translating
      *                                               violation messages
      */
-    public function __construct(TranslatorInterface $translator, string $translationDomain = null)
+    public function __construct($translator, string $translationDomain = null)
     {
+        if (!$translator instanceof LegacyTranslatorInterface && !$translator instanceof TranslatorInterface) {
+            throw new \TypeError(sprintf('Argument 1 passed to %s() must be an instance of %s, %s given.', __METHOD__, TranslatorInterface::class, \is_object($translator) ? \get_class($translator) : \gettype($translator)));
+        }
+
         $this->translator = $translator;
         $this->translationDomain = $translationDomain;
     }

src/Symfony/Component/Validator/Util/LegacyTranslatorProxy.php

@@ -17,7 +17,7 @@ use Symfony\Contracts\Translation\TranslatorInterface;
 /**
  * @internal to be removed in Symfony 5.0.
  */
-class LegacyTranslatorProxy implements LegacyTranslatorInterface
+class LegacyTranslatorProxy implements LegacyTranslatorInterface, TranslatorInterface
 {
     private $translator;
 
@@ -60,6 +60,6 @@ class LegacyTranslatorProxy implements LegacyTranslatorInterface
      */
     public function transChoice($id, $number, array $parameters = array(), $domain = null, $locale = null)
     {
-        return $this->translator->transChoice($id, $number, $parameters, $domain, $locale);
+        return $this->translator->trans($id, array('%count%' => $number) + $parameters, $domain, $locale);
     }
 }

src/Symfony/Component/Validator/Violation/ConstraintViolationBuilder.php

@@ -11,6 +11,7 @@
 
 namespace Symfony\Component\Validator\Violation;
 
+use Symfony\Component\Translation\TranslatorInterface as LegacyTranslatorInterface;
 use Symfony\Component\Validator\Constraint;
 use Symfony\Component\Validator\ConstraintViolation;
 use Symfony\Component\Validator\ConstraintViolationList;
@@ -43,8 +44,14 @@ class ConstraintViolationBuilder implements ConstraintViolationBuilderInterface
      */
     private $cause;
 
-    public function __construct(ConstraintViolationList $violations, Constraint $constraint, $message, array $parameters, $root, $propertyPath, $invalidValue, TranslatorInterface $translator, $translationDomain = null)
+    /**
+     * @param TranslatorInterface $translator
+     */
+    public function __construct(ConstraintViolationList $violations, Constraint $constraint, $message, array $parameters, $root, $propertyPath, $invalidValue, $translator, $translationDomain = null)
     {
+        if (!$translator instanceof LegacyTranslatorInterface && !$translator instanceof TranslatorInterface) {
+            throw new \TypeError(sprintf('Argument 8 passed to %s() must be an instance of %s, %s given.', __METHOD__, TranslatorInterface::class, \is_object($translator) ? \get_class($translator) : \gettype($translator)));
+        }
         $this->violations = $violations;
         $this->message = $message;
         $this->parameters = $parameters;
@@ -147,6 +154,12 @@ class ConstraintViolationBuilder implements ConstraintViolationBuilderInterface
                 $this->parameters,
                 $this->translationDomain
             );
+        } elseif ($this->translator instanceof TranslatorInterface) {
+            $translatedMessage = $this->translator->trans(
+                $this->message,
+                array('%count%' => $this->plural) + $this->parameters,
+                $this->translationDomain
+            );
         } else {
             try {
                 $translatedMessage = $this->translator->transChoice(

src/Symfony/Contracts/Tests/Translation/TranslatorTest.php

@@ -50,24 +50,24 @@ class TranslatorTest extends TestCase
     /**
      * @dataProvider getTransChoiceTests
      */
-    public function testTransChoiceWithExplicitLocale($expected, $id, $number, $parameters)
+    public function testTransChoiceWithExplicitLocale($expected, $id, $number)
     {
         $translator = $this->getTranslator();
         $translator->setLocale('en');
 
-        $this->assertEquals($expected, $translator->transChoice($id, $number, $parameters));
+        $this->assertEquals($expected, $translator->trans($id, array('%count%' => $number)));
     }
 
     /**
      * @dataProvider getTransChoiceTests
      */
-    public function testTransChoiceWithDefaultLocale($expected, $id, $number, $parameters)
+    public function testTransChoiceWithDefaultLocale($expected, $id, $number)
     {
         \Locale::setDefault('en');
 
         $translator = $this->getTranslator();
 
-        $this->assertEquals($expected, $translator->transChoice($id, $number, $parameters));
+        $this->assertEquals($expected, $translator->trans($id, array('%count%' => $number)));
     }
 
     public function testGetSetLocale()
@@ -103,14 +103,14 @@ class TranslatorTest extends TestCase
     public function getTransChoiceTests()
     {
         return array(
-            array('There are no apples', '{0} There are no apples|{1} There is one apple|]1,Inf] There are %count% apples', 0, array('%count%' => 0)),
+            array('There are no apples', '{0} There are no apples|{1} There is one apple|]1,Inf] There are %count% apples', 0),
-            array('There is one apple', '{0} There are no apples|{1} There is one apple|]1,Inf] There are %count% apples', 1, array('%count%' => 1)),
+            array('There is one apple', '{0} There are no apples|{1} There is one apple|]1,Inf] There are %count% apples', 1),
-            array('There are 10 apples', '{0} There are no apples|{1} There is one apple|]1,Inf] There are %count% apples', 10, array('%count%' => 10)),
+            array('There are 10 apples', '{0} There are no apples|{1} There is one apple|]1,Inf] There are %count% apples', 10),
-            array('There are 0 apples', 'There is 1 apple|There are %count% apples', 0, array('%count%' => 0)),
+            array('There are 0 apples', 'There is 1 apple|There are %count% apples', 0),
-            array('There is 1 apple', 'There is 1 apple|There are %count% apples', 1, array('%count%' => 1)),
+            array('There is 1 apple', 'There is 1 apple|There are %count% apples', 1),
-            array('There are 10 apples', 'There is 1 apple|There are %count% apples', 10, array('%count%' => 10)),
+            array('There are 10 apples', 'There is 1 apple|There are %count% apples', 10),
             // custom validation messages may be coded with a fixed value
-            array('There are 2 apples', 'There are 2 apples', 2, array('%count%' => 2)),
+            array('There are 2 apples', 'There are 2 apples', 2),
         );
     }
 
@@ -121,7 +121,7 @@ class TranslatorTest extends TestCase
     {
         $translator = $this->getTranslator();
 
-        $this->assertEquals($expected, $translator->transChoice($interval.' foo|[1,Inf[ bar', $number));
+        $this->assertEquals($expected, $translator->trans($interval.' foo|[1,Inf[ bar', array('%count%' => $number)));
     }
 
     public function getInternal()
@@ -146,14 +146,14 @@ class TranslatorTest extends TestCase
     {
         $translator = $this->getTranslator();
 
-        $this->assertEquals($expected, $translator->transChoice($id, $number));
+        $this->assertEquals($expected, $translator->trans($id, array('%count%' => $number)));
     }
 
     public function testReturnMessageIfExactlyOneStandardRuleIsGiven()
     {
         $translator = $this->getTranslator();
 
-        $this->assertEquals('There are two apples', $translator->transChoice('There are two apples', 2));
+        $this->assertEquals('There are two apples', $translator->trans('There are two apples', array('%count%' => 2)));
     }
 
     /**
@@ -164,7 +164,7 @@ class TranslatorTest extends TestCase
     {
         $translator = $this->getTranslator();
 
-        $translator->transChoice($id, $number);
+        $translator->trans($id, array('%count%' => $number));
     }
 
     public function getNonMatchingMessages()
@@ -186,29 +186,29 @@ class TranslatorTest extends TestCase
 
             array('There is one apple', '{0} There are no apples|{1} There is one apple|]1,Inf] There are %count% apples', 1),
 
-            array('There are %count% apples', '{0} There are no apples|{1} There is one apple|]1,Inf] There are %count% apples', 10),
+            array('There are 10 apples', '{0} There are no apples|{1} There is one apple|]1,Inf] There are %count% apples', 10),
-            array('There are %count% apples', '{0} There are no apples|{1} There is one apple|]1,Inf]There are %count% apples', 10),
+            array('There are 10 apples', '{0} There are no apples|{1} There is one apple|]1,Inf]There are %count% apples', 10),
-            array('There are %count% apples', '{0} There are no apples|{1} There is one apple|]1,Inf]     There are %count% apples', 10),
+            array('There are 10 apples', '{0} There are no apples|{1} There is one apple|]1,Inf]     There are %count% apples', 10),
 
-            array('There are %count% apples', 'There is one apple|There are %count% apples', 0),
+            array('There are 0 apples', 'There is one apple|There are %count% apples', 0),
             array('There is one apple', 'There is one apple|There are %count% apples', 1),
-            array('There are %count% apples', 'There is one apple|There are %count% apples', 10),
+            array('There are 10 apples', 'There is one apple|There are %count% apples', 10),
 
-            array('There are %count% apples', 'one: There is one apple|more: There are %count% apples', 0),
+            array('There are 0 apples', 'one: There is one apple|more: There are %count% apples', 0),
             array('There is one apple', 'one: There is one apple|more: There are %count% apples', 1),
-            array('There are %count% apples', 'one: There is one apple|more: There are %count% apples', 10),
+            array('There are 10 apples', 'one: There is one apple|more: There are %count% apples', 10),
 
             array('There are no apples', '{0} There are no apples|one: There is one apple|more: There are %count% apples', 0),
             array('There is one apple', '{0} There are no apples|one: There is one apple|more: There are %count% apples', 1),
-            array('There are %count% apples', '{0} There are no apples|one: There is one apple|more: There are %count% apples', 10),
+            array('There are 10 apples', '{0} There are no apples|one: There is one apple|more: There are %count% apples', 10),
 
             array('', '{0}|{1} There is one apple|]1,Inf] There are %count% apples', 0),
             array('', '{0} There are no apples|{1}|]1,Inf] There are %count% apples', 1),
 
             // Indexed only tests which are Gettext PoFile* compatible strings.
-            array('There are %count% apples', 'There is one apple|There are %count% apples', 0),
+            array('There are 0 apples', 'There is one apple|There are %count% apples', 0),
             array('There is one apple', 'There is one apple|There are %count% apples', 1),
-            array('There are %count% apples', 'There is one apple|There are %count% apples', 2),
+            array('There are 2 apples', 'There is one apple|There are %count% apples', 2),
 
             // Tests for float numbers
             array('There is almost one apple', '{0} There are no apples|]0,1[ There is almost one apple|{1} There is one apple|[1,Inf] There is more than one apple', 0.7),

src/Symfony/Contracts/Translation/TranslatorInterface.php

@@ -19,19 +19,8 @@ interface TranslatorInterface
     /**
      * Translates the given message.
      *
-     * @param string      $id         The message id (may also be an object that can be cast to string)
+     * When a number is provided as a parameter named "%count%", the message is parsed for plural
-     * @param array       $parameters An array of parameters for the message
+     * forms and a translation is chosen according to this number using the following rules:
-     * @param string|null $domain     The domain for the message or null to use the default
-     * @param string|null $locale     The locale or null to use the default
-     *
-     * @return string The translated string
-     *
-     * @throws \InvalidArgumentException If the locale contains invalid characters
-     */
-    public function trans($id, array $parameters = array(), $domain = null, $locale = null);
-
-    /**
-     * Translates the given choice message by choosing a translation according to a number.
      *
      * Given a message with different plural translations separated by a
      * pipe (|), this method returns the correct portion of the message based
@@ -64,7 +53,6 @@ interface TranslatorInterface
      * @see https://en.wikipedia.org/wiki/ISO_31-11
      *
      * @param string      $id         The message id (may also be an object that can be cast to string)
-     * @param int         $number     The number to use to find the indice of the message
      * @param array       $parameters An array of parameters for the message
      * @param string|null $domain     The domain for the message or null to use the default
      * @param string|null $locale     The locale or null to use the default
@@ -73,7 +61,7 @@ interface TranslatorInterface
      *
      * @throws \InvalidArgumentException If the locale contains invalid characters
      */
-    public function transChoice($id, $number, array $parameters = array(), $domain = null, $locale = null);
+    public function trans($id, array $parameters = array(), $domain = null, $locale = null);
 
     /**
      * Sets the current locale.

src/Symfony/Contracts/Translation/TranslatorTrait.php

@@ -42,17 +42,14 @@ trait TranslatorTrait
      * {@inheritdoc}
      */
     public function trans($id, array $parameters = array(), $domain = null, $locale = null)
-    {
-        return strtr((string) $id, $parameters);
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    public function transChoice($id, $number, array $parameters = array(), $domain = null, $locale = null)
     {
         $id = (string) $id;
-        $number = (float) $number;
+
+        if (!isset($parameters['%count%']) || !is_numeric($parameters['%count%'])) {
+            return strtr($id, $parameters);
+        }
+
+        $number = (float) $parameters['%count%'];
         $locale = (string) $locale ?: $this->getLocale();
 
         $parts = array();