fix(symfony): skip ErrorResourceAttributeLoaderPass on Symfony 6.4

src/Symfony/Bundle/DependencyInjection/Compiler/ErrorResourceAttributeLoaderPass.php

@@ -18,6 +18,7 @@
 use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\Definition;
+use Symfony\Component\Serializer\Mapping\Loader\AnnotationLoader;
 use Symfony\Component\Serializer\Mapping\Loader\AttributeLoader;
 
 /**
@@ -43,15 +44,32 @@ public function process(ContainerBuilder $container): void
             return;
         }
 
+        // Symfony 6.4 ships an AttributeLoader with a different constructor signature
+        // (`?Doctrine\Common\Annotations\Reader`), incompatible with the `allowAnyClass`/`mappedClasses`
+        // arguments below. The `AnnotationLoader` class only exists on the 6.4 branch
+        // (removed in 7.0), so its presence is a reliable marker for that signature. See #8244.
+        if (class_exists(AnnotationLoader::class)) {
+            return;
+        }
+
+        $chainLoader = $container->getDefinition('serializer.mapping.chain_loader');
+        $loaders = $chainLoader->getArgument(0);
+
+        // Skip when Symfony already wired an AttributeLoader (i.e. `enable_attributes: true`).
+        // Adding another one would duplicate work and re-process every class twice.
+        foreach ($loaders as $loader) {
+            if ($loader instanceof Definition && is_a($loader->getClass(), AttributeLoader::class, true)) {
+                return;
+            }
+        }
+
         $mappedClasses = [
             Error::class => [Error::class],
             ValidationException::class => [ValidationException::class],
         ];
 
         $loaderDefinition = new Definition(AttributeLoader::class, [true, $mappedClasses]);
 
-        $chainLoader = $container->getDefinition('serializer.mapping.chain_loader');
-        $loaders = $chainLoader->getArgument(0);
         $loaders[] = $loaderDefinition;
         $chainLoader->replaceArgument(0, $loaders);
 

tests/Symfony/Bundle/DependencyInjection/Compiler/ErrorResourceAttributeLoaderPassTest.php

@@ -78,6 +78,41 @@ public function testDoesNothingWhenChainLoaderIsAbsent(): void
         $this->assertFalse($container->hasDefinition('serializer.mapping.chain_loader'));
     }
 
+    public function testDoesNothingWhenChainAlreadyContainsAnAttributeLoader(): void
+    {
+        $container = new ContainerBuilder();
+        $existing = new Definition(AttributeLoader::class);
+        $container->setDefinition('serializer.mapping.chain_loader', new Definition(LoaderChain::class, [[$existing]]));
+        $container->setDefinition('serializer.mapping.cache_warmer', new Definition(\stdClass::class, [[$existing]]));
+
+        (new ErrorResourceAttributeLoaderPass())->process($container);
+
+        $loaders = $container->getDefinition('serializer.mapping.chain_loader')->getArgument(0);
+        $this->assertCount(1, $loaders, 'pass must not add another AttributeLoader when one is already wired (enable_attributes: true).');
+
+        $warmerLoaders = $container->getDefinition('serializer.mapping.cache_warmer')->getArgument(0);
+        $this->assertCount(1, $warmerLoaders);
+    }
+
+    /**
+     * @see https://github.com/api-platform/core/issues/8244
+     */
+    public function testSkipsOnSymfony64SerializerSignature(): void
+    {
+        if (!class_exists(\Symfony\Component\Serializer\Mapping\Loader\AnnotationLoader::class)) {
+            $this->markTestSkipped('Only relevant when running against symfony/serializer 6.4 (AnnotationLoader still present).');
+        }
+
+        $container = new ContainerBuilder();
+        $container->setDefinition('serializer.mapping.chain_loader', new Definition(LoaderChain::class, [[]]));
+        $container->setDefinition('serializer.mapping.cache_warmer', new Definition(\stdClass::class, [[]]));
+
+        (new ErrorResourceAttributeLoaderPass())->process($container);
+
+        $this->assertSame([], $container->getDefinition('serializer.mapping.chain_loader')->getArgument(0));
+        $this->assertSame([], $container->getDefinition('serializer.mapping.cache_warmer')->getArgument(0));
+    }
+
     /**
      * Mirrors the runtime behavior with `framework.serializer.enable_attributes: false`:
      * Symfony builds the `AttributeLoader` with `allowAnyClass = false` and no mapped classes,