[2.7] Fix docblocks about callables

src/Symfony/Bridge/Twig/Command/DebugCommand.php

@@ -150,7 +150,7 @@ EOF
                     return;
                 }
                 $refl = new \ReflectionMethod($cb[0], $cb[1]);
-            } elseif (is_object($cb) && is_callable($cb)) {
+            } elseif (is_object($cb) && method_exists($cb, '__invoke')) {
                 $refl = new \ReflectionMethod($cb, '__invoke');
             } elseif (function_exists($cb)) {
                 $refl = new \ReflectionFunction($cb);

src/Symfony/Bundle/FrameworkBundle/Resources/config/debug_prod.xml

@@ -14,7 +14,7 @@
         <service id="debug.debug_handlers_listener" class="%debug.debug_handlers_listener.class%">
             <tag name="kernel.event_subscriber" />
             <tag name="monolog.logger" channel="php" />
-            <argument /><!-- Exception handler -->
+            <argument>null</argument><!-- Exception handler -->
             <argument type="service" id="logger" on-invalid="null" />
             <argument>null</argument><!-- Log levels map for enabled error levels -->
             <argument>null</argument>

src/Symfony/Component/Console/Question/Question.php

@@ -217,7 +217,7 @@ class Question
      *
      * The normalizer can be a callable (a string), a closure or a class implementing __invoke.
      *
-     * @param string|\Closure $normalizer
+     * @param callable $normalizer
      *
      * @return Question The current instance
      */
@@ -233,7 +233,7 @@ class Question
      *
      * The normalizer can ba a callable (a string), a closure or a class implementing __invoke.
      *
-     * @return string|\Closure
+     * @return callable
      */
     public function getNormalizer()
     {

src/Symfony/Component/Serializer/Normalizer/AbstractNormalizer.php

@@ -105,7 +105,7 @@ abstract class AbstractNormalizer extends SerializerAwareNormalizer implements N
     /**
      * Set normalization callbacks.
      *
-     * @param array $callbacks help normalize the result
+     * @param callable[] $callbacks help normalize the result
      *
      * @return self
      *