[DependencyInjection][Routing] Deprecate XML configuration format

Author: MatTheCat

CHANGELOG.md

@@ -12,6 +12,7 @@ CHANGELOG
  * Deprecate class aliases in the `Annotation` namespace, use attributes instead
  * Deprecate getters and setters in attribute classes in favor of public properties
  * Deprecate accessing the internal scope of the loader in PHP config files, use only its public API instead
+ * Deprecate XML configuration format, use YAML, PHP or attributes instead
 
 7.3
 ---

Loader/XmlFileLoader.php

@@ -24,6 +24,8 @@
  *
  * @author Fabien Potencier <fabien@symfony.com>
  * @author Tobias Schultze <http://tobion.de>
+ *
+ * @deprecated since Symfony 7.4, use another loader instead
  */
 class XmlFileLoader extends FileLoader
 {
@@ -40,6 +42,8 @@ class XmlFileLoader extends FileLoader
      */
     public function load(mixed $file, ?string $type = null): RouteCollection
     {
+        trigger_deprecation('symfony/routing', '7.4', 'XML configuration format is deprecated, use YAML, PHP or attributes instead.');
+
         $path = $this->locator->locate($file);
 
         $xml = $this->loadFile($path);

Tests/Loader/XmlFileLoaderTest.php

@@ -12,6 +12,8 @@
 namespace Symfony\Component\Routing\Tests\Loader;
 
 use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\Attributes\Group;
+use PHPUnit\Framework\Attributes\IgnoreDeprecations;
 use PHPUnit\Framework\TestCase;
 use Symfony\Component\Config\FileLocator;
 use Symfony\Component\Config\Loader\LoaderResolver;
@@ -24,6 +26,8 @@
 use Symfony\Component\Routing\Tests\Fixtures\CustomXmlFileLoader;
 use Symfony\Component\Routing\Tests\Fixtures\Psr4Controllers\MyController;
 
+#[IgnoreDeprecations]
+#[Group('legacy')]
 class XmlFileLoaderTest extends TestCase
 {
     public function testSupports()