[FrameworkBundle] [DependencyInjection] added logging of unused tags during container compilation

src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Compiler/UnusedTagsPass.php

@@ -0,0 +1,86 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler;
+
+use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+
+/**
+ * Find all service tags which are defined, but not used and yield a warning log message.
+ *
+ * @author Florian Pfitzer <pfitzer@wurzel3.de>
+ */
+class UnusedTagsPass implements CompilerPassInterface
+{
+    /**
+     * whitelisted tags
+     *
+     * @var array
+     */
+    protected $whitelist = array(
+        "console.command",
+        "data_collector",
+        "form.type",
+        "form.type_extension",
+        "form.type_guesser",
+        "kernel.cache_clearer",
+        "kernel.cache_warmer",
+        "kernel.event_listener",
+        "kernel.event_subscriber",
+        "kernel.fragment_renderer",
+        "monolog.logger",
+        "routing.loader",
+        "security.remember_me_aware",
+        "security.voter",
+        "serializer.encoder",
+        "templating.helper",
+        "translation.dumper",
+        "translation.extractor",
+        "translation.loader",
+        "twig.extension",
+        "twig.loader",
+        "validator.constraint_validator",
+        "validator.initializer",
+    );
+
+    public function process(ContainerBuilder $container)
+    {
+        $compiler = $container->getCompiler();
+        $formatter = $compiler->getLoggingFormatter();
+        $tags = $container->findTags();
+
+        $unusedTags = $container->findUnusedTags();
+        foreach ($unusedTags as $tag) {
+            // skip whitelisted tags
+            if (in_array($tag, $this->whitelist)) {
+                continue;
+            }
+            // check for typos
+            $candidates = array();
+            foreach ($tags as $definedTag) {
+                if ($definedTag === $tag) {
+                    continue;
+                }
+                if (false !== strpos($definedTag, $tag) || levenshtein($tag, $definedTag) <= strlen($tag) / 3) {
+                    $candidates[] = $definedTag;
+                }
+            }
+
+            $services = array_keys($container->findTaggedServiceIds($tag));
+            $message = sprintf('Tag "%s" was defined on the service(s) %s, but was never used.', $tag, implode(',', $services));
+            if (!empty($candidates)) {
+                $message .= sprintf(' Did you mean "%s"?', implode('", "', $candidates));
+            }
+            $compiler->addLogMessage($formatter->format($this, $message));
+        }
+    }
+}

src/Symfony/Bundle/FrameworkBundle/FrameworkBundle.php

@@ -28,6 +28,7 @@ use Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler\CompilerDebugDum
 use Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler\TranslationExtractorPass;
 use Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler\TranslationDumperPass;
 use Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler\SerializerPass;
+use Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler\UnusedTagsPass;
 use Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler\ConfigCachePass;
 use Symfony\Component\Debug\ErrorHandler;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
@@ -89,6 +90,7 @@ class FrameworkBundle extends Bundle
         $container->addCompilerPass(new TranslationDumperPass());
         $container->addCompilerPass(new FragmentRendererPass(), PassConfig::TYPE_AFTER_REMOVING);
         $container->addCompilerPass(new SerializerPass());
+        $container->addCompilerPass(new UnusedTagsPass(), PassConfig::TYPE_AFTER_REMOVING);
 
         if ($container->getParameter('kernel.debug')) {
             $container->addCompilerPass(new ContainerBuilderDebugDumpPass(), PassConfig::TYPE_AFTER_REMOVING);

src/Symfony/Component/DependencyInjection/ContainerBuilder.php

@@ -90,6 +90,11 @@ class ContainerBuilder extends Container implements TaggedContainerInterface
      */
     private $expressionLanguageProviders = array();
 
+    /**
+     * @var array with tag names used by findTaggedServiceIds
+     */
+    private $usedTags = array();
+
     /**
      * Sets the track resources flag.
      *
@@ -1064,6 +1069,7 @@ class ContainerBuilder extends Container implements TaggedContainerInterface
      */
     public function findTaggedServiceIds($name)
     {
+        $this->usedTags[] = $name;
         $tags = array();
         foreach ($this->getDefinitions() as $id => $definition) {
             if ($definition->hasTag($name)) {
@@ -1089,6 +1095,19 @@ class ContainerBuilder extends Container implements TaggedContainerInterface
         return array_unique($tags);
     }
 
+    /**
+     * Returns all tags not queried by findTaggedServiceIds
+     *
+     * @return array An array of tags
+     */
+    public function findUnusedTags()
+    {
+        $tags = array_values(array_diff($this->findTags(), $this->usedTags));
+        $tags = array_unique($tags);
+
+        return $tags;
+    }
+
     public function addExpressionLanguageProvider(ExpressionFunctionProviderInterface $provider)
     {
         $this->expressionLanguageProviders[] = $provider;

src/Symfony/Component/DependencyInjection/Tests/ContainerBuilderTest.php

@@ -560,6 +560,18 @@ class ContainerBuilderTest extends \PHPUnit_Framework_TestCase
         $this->assertEquals(array(), $builder->findTaggedServiceIds('foobar'), '->findTaggedServiceIds() returns an empty array if there is annotated services');
     }
 
+    public function testFindUnusedTags()
+    {
+        $builder = new ContainerBuilder();
+        $builder
+            ->register('foo', 'Bar\FooClass')
+            ->addTag('kernel.event_listener', array('foo' => 'foo'))
+            ->addTag('kenrel.event_listener', array('bar' => 'bar'))
+        ;
+        $builder->findTaggedServiceIds('kernel.event_listener');
+        $this->assertEquals(array('kenrel.event_listener'), $builder->findUnusedTags(), '->findUnusedTags() returns an array with unused tags');
+    }
+
     /**
      * @covers Symfony\Component\DependencyInjection\ContainerBuilder::findDefinition
      */