Merge branch '4.4'

* 4.4: (30 commits)
  fix merge
  fix merge
  [HttpClient] fix debug output added to stderr at shutdown
  fix cs
  [Mailer] fixed logic
  fixed missing license
  Add a new ErrorHandler component (mirror of the Debug component)
  Use mocks before replacing the error handler
  [Config] Do not use absolute path when computing the vendor freshness
  [Process] Path resolution for FCGI configuration
  Bump minimum version of symfony/phpunit-bridge
  Container*::getServiceIds() should return an array of string
  [Config][ReflectionClassResource] Use ternary instead of null coaelscing operator
  [Validator] Add missing Russian and Ukrainian translations
  [Translation] Use HTTPS and fix a url
  [Config] Fix for signatures of typed properties
  [Validator] Add missing Hungarian translations
  [Validator] Add Lithuanian translation for Range validator
  Add HTTPS to a URL
  sync translation files
  ...

Author: nicolas-grekas

Legacy/SymfonyTestsListenerTrait.php

@@ -18,7 +18,8 @@
 use PHPUnit\Util\Blacklist;
 use Symfony\Bridge\PhpUnit\ClockMock;
 use Symfony\Bridge\PhpUnit\DnsMock;
-use Symfony\Component\Debug\DebugClassLoader;
+use Symfony\Component\Debug\DebugClassLoader as LegacyDebugClassLoader;
+use Symfony\Component\ErrorHandler\DebugClassLoader;
 
 /**
  * PHP 5.3 compatible trait-like shared implementation.
@@ -53,7 +54,7 @@ public function __construct(array $mockedNamespaces = array())
             Blacklist::$blacklistedClassNames['\Symfony\Bridge\PhpUnit\Legacy\SymfonyTestsListenerTrait'] = 2;
         }
 
-        $enableDebugClassLoader = class_exists('Symfony\Component\Debug\DebugClassLoader');
+        $enableDebugClassLoader = class_exists(DebugClassLoader::class) || class_exists(LegacyDebugClassLoader::class);
 
         foreach ($mockedNamespaces as $type => $namespaces) {
             if (!\is_array($namespaces)) {
@@ -74,7 +75,11 @@ public function __construct(array $mockedNamespaces = array())
             }
         }
         if ($enableDebugClassLoader) {
-            DebugClassLoader::enable();
+            if (class_exists(DebugClassLoader::class)) {
+                DebugClassLoader::enable();
+            } else {
+                LegacyDebugClassLoader::enable();
+            }
         }
         if (self::$globallyEnabled) {
             $this->state = -2;

composer.json

@@ -21,7 +21,7 @@
         "php": ">=5.5.9"
     },
     "suggest": {
-        "symfony/debug": "For tracking deprecated interfaces usages at runtime with DebugClassLoader"
+        "symfony/error-handler": "For tracking deprecated interfaces usages at runtime with DebugClassLoader"
     },
     "conflict": {
         "phpunit/phpunit": "<5.4.3"