From 90fd3ffeb79a350b8373b3eae08c94318498a64e Mon Sep 17 00:00:00 2001
From: Ruud Kamphuis <ruudk@users.noreply.github.com>
Date: Wed, 18 Jun 2025 12:27:01 +0200
Subject: [PATCH] [DependencyInjection] Allow extending `#[AsAlias]` attribute

---
 .../DependencyInjection/Attribute/AsAlias.php |  2 +-
 .../DependencyInjection/CHANGELOG.md          |  5 ++++
 .../DependencyInjection/Loader/FileLoader.php |  2 +-
 .../PrototypeAsAlias/WithCustomAsAlias.php    | 25 +++++++++++++++++++
 .../Tests/Loader/FileLoaderTest.php           |  3 +++
 5 files changed, 35 insertions(+), 2 deletions(-)
 create mode 100644 src/Symfony/Component/DependencyInjection/Tests/Fixtures/PrototypeAsAlias/WithCustomAsAlias.php

diff --git a/src/Symfony/Component/DependencyInjection/Attribute/AsAlias.php b/src/Symfony/Component/DependencyInjection/Attribute/AsAlias.php
index 0839afa48ff44..c74b0923dfedd 100644
--- a/src/Symfony/Component/DependencyInjection/Attribute/AsAlias.php
+++ b/src/Symfony/Component/DependencyInjection/Attribute/AsAlias.php
@@ -17,7 +17,7 @@
  * @author Alan Poulain <contact@alanpoulain.eu>
  */
 #[\Attribute(\Attribute::TARGET_CLASS | \Attribute::IS_REPEATABLE)]
-final class AsAlias
+class AsAlias
 {
     /**
      * @var list<string>
diff --git a/src/Symfony/Component/DependencyInjection/CHANGELOG.md b/src/Symfony/Component/DependencyInjection/CHANGELOG.md
index df3486a9dc867..5c6c41cfdf27b 100644
--- a/src/Symfony/Component/DependencyInjection/CHANGELOG.md
+++ b/src/Symfony/Component/DependencyInjection/CHANGELOG.md
@@ -1,6 +1,11 @@
 CHANGELOG
 =========
 
+7.4
+---
+
+ * Allow `#[AsAlias]` to be extended
+
 7.3
 ---
 
diff --git a/src/Symfony/Component/DependencyInjection/Loader/FileLoader.php b/src/Symfony/Component/DependencyInjection/Loader/FileLoader.php
index bc38767bcb546..3cf23cf98eab4 100644
--- a/src/Symfony/Component/DependencyInjection/Loader/FileLoader.php
+++ b/src/Symfony/Component/DependencyInjection/Loader/FileLoader.php
@@ -216,7 +216,7 @@ public function registerClasses(Definition $prototype, string $namespace, string
             }
             $r = $this->container->getReflectionClass($class);
             $defaultAlias = 1 === \count($interfaces) ? $interfaces[0] : null;
-            foreach ($r->getAttributes(AsAlias::class) as $attr) {
+            foreach ($r->getAttributes(AsAlias::class, \ReflectionAttribute::IS_INSTANCEOF) as $attr) {
                 /** @var AsAlias $attribute */
                 $attribute = $attr->newInstance();
                 $alias = $attribute->id ?? $defaultAlias;
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/PrototypeAsAlias/WithCustomAsAlias.php b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/PrototypeAsAlias/WithCustomAsAlias.php
new file mode 100644
index 0000000000000..4f141909890d2
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/PrototypeAsAlias/WithCustomAsAlias.php
@@ -0,0 +1,25 @@
+<?php
+
+namespace Symfony\Component\DependencyInjection\Tests\Fixtures\PrototypeAsAlias;
+
+use Symfony\Component\DependencyInjection\Attribute\AsAlias;
+
+#[AsProductionAlias(id: AliasFooInterface::class)]
+class WithCustomAsAlias
+{
+}
+
+#[\Attribute(\Attribute::TARGET_CLASS | \Attribute::IS_REPEATABLE)]
+final class AsProductionAlias extends AsAlias
+{
+    /**
+     * @param string|null         $id     The id of the alias
+     * @param bool                $public Whether to declare the alias public
+     */
+    public function __construct(
+        public ?string $id = null,
+        public bool $public = false,
+    ) {
+        parent::__construct($id, $public, ['prod']);
+    }
+}
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Loader/FileLoaderTest.php b/src/Symfony/Component/DependencyInjection/Tests/Loader/FileLoaderTest.php
index 0ad1b363cf6bf..17bc228c77b82 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Loader/FileLoaderTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/Loader/FileLoaderTest.php
@@ -45,6 +45,7 @@
 use Symfony\Component\DependencyInjection\Tests\Fixtures\PrototypeAsAlias\WithAsAliasInterface;
 use Symfony\Component\DependencyInjection\Tests\Fixtures\PrototypeAsAlias\WithAsAliasMultiple;
 use Symfony\Component\DependencyInjection\Tests\Fixtures\PrototypeAsAlias\WithAsAliasProdEnv;
+use Symfony\Component\DependencyInjection\Tests\Fixtures\PrototypeAsAlias\WithCustomAsAlias;
 use Symfony\Component\DependencyInjection\Tests\Fixtures\Utils\NotAService;
 
 class FileLoaderTest extends TestCase
@@ -368,6 +369,8 @@ public function testRegisterClassesWithAsAlias(string $resource, array $expected
     public static function provideResourcesWithAsAliasAttributes(): iterable
     {
         yield 'Private' => ['PrototypeAsAlias/{WithAsAlias,AliasFooInterface}.php', [AliasFooInterface::class => new Alias(WithAsAlias::class)]];
+        yield 'PrivateCustomAlias' => ['PrototypeAsAlias/{WithCustomAsAlias,AliasFooInterface}.php', [AliasFooInterface::class => new Alias(WithCustomAsAlias::class)], 'prod'];
+        yield 'PrivateCustomAliasNoMatch' => ['PrototypeAsAlias/{WithCustomAsAlias,AliasFooInterface}.php', [], 'dev'];
         yield 'Interface' => ['PrototypeAsAlias/{WithAsAliasInterface,AliasFooInterface}.php', [AliasFooInterface::class => new Alias(WithAsAliasInterface::class)]];
         yield 'Multiple' => ['PrototypeAsAlias/{WithAsAliasMultiple,AliasFooInterface}.php', [
             AliasFooInterface::class => new Alias(WithAsAliasMultiple::class, true),