[DI] accept null index in #[TaggedItem]

Author: nicolas-grekas

Attribute/TaggedItem.php

@@ -20,7 +20,7 @@
 class TaggedItem
 {
     public function __construct(
-        public string $index,
+        public ?string $index = null,
         public ?int $priority = null,
     ) {
     }

Tests/Compiler/PriorityTaggedServiceTraitTest.php

@@ -205,13 +205,17 @@ public function testTaggedItemAttributes()
                 HelloNamedService::class => (new ChildDefinition(''))->addTag('my_custom_tag'),
                 \stdClass::class => (new ChildDefinition(''))->addTag('my_custom_tag2'),
             ]);
+        $container->register('service3', HelloNamedService2::class)
+            ->setAutoconfigured(true)
+            ->addTag('my_custom_tag');
 
         (new ResolveInstanceofConditionalsPass())->process($container);
 
         $priorityTaggedServiceTraitImplementation = new PriorityTaggedServiceTraitImplementation();
 
         $tag = new TaggedIteratorArgument('my_custom_tag', 'foo', 'getFooBar');
         $expected = [
+            'service3' => new TypedReference('service3', HelloNamedService2::class),
             'hello' => new TypedReference('service2', HelloNamedService::class),
             'service1' => new TypedReference('service1', FooTagClass::class),
         ];
@@ -235,3 +239,8 @@ public function test($tagName, ContainerBuilder $container)
 class HelloNamedService extends \stdClass
 {
 }
+
+#[TaggedItem(priority: 2)]
+class HelloNamedService2
+{
+}