Replace Attributes::$visited array with WeakMap

The circular-reference guard keyed visited objects by spl_object_id(), which is
recycled once an object is garbage-collected. On a reused validator instance
this caused two problems: unbounded growth of the visited map across calls, and
false circular-reference failures when a fresh object inherited a freed ID.

WeakMap is keyed by object identity, so distinct objects can never collide, and
entries are reclaimed automatically when the key object is garbage-collected,
no manual reset is required. Since WeakMap is not serializable, __sleep excludes
the field and __wakeup reinitializes it, which also avoids carrying stale IDs
across unserialize.

Author: henriquemoody

src/Validators/Attributes.php

@@ -28,8 +28,6 @@
 use Respect\Validation\Validators\Attributes\PropertyResolver;
 use Respect\Validation\Validators\Core\Reducer;
 
-use function spl_object_id;
-
 #[Composable(without: [All::class, Key::class, Property::class, Not::class, UndefOr::class])]
 #[Attribute(Attribute::TARGET_PROPERTY | Attribute::IS_REPEATABLE)]
 #[Template(
@@ -41,8 +39,8 @@ final class Attributes implements Validator
 {
     public const string TEMPLATE_CIRCULAR_REFERENCE = '__circular_reference__';
 
-    /** @var array<int, true> */
-    private array $visited = [];
+    /** @var \WeakMap<object, true> */
+    private \WeakMap $visited;
 
     private readonly PropertyResolver $propertyResolver;
 
@@ -53,6 +51,18 @@ public function __construct(
             new ExplicitAttributePropertyResolver(),
             new DeclaredTypePropertyResolver(),
         );
+        $this->visited = new \WeakMap();
+    }
+
+    /** @return list<string> */
+    public function __sleep(): array
+    {
+        return ['propertyResolver'];
+    }
+
+    public function __wakeup(): void
+    {
+        $this->visited = new \WeakMap();
     }
 
     public function evaluate(mixed $input): Result
@@ -63,12 +73,11 @@ public function evaluate(mixed $input): Result
             return $objectType->withId($id);
         }
 
-        $objectId = spl_object_id($input);
-        if (isset($this->visited[$objectId])) {
+        if ($this->visited->offsetExists($input)) {
             return Result::failed($input, $this, [], self::TEMPLATE_CIRCULAR_REFERENCE)->withId($id);
         }
 
-        $this->visited[$objectId] = true;
+        $this->visited[$input] = true;
 
         $reflection = new ReflectionObject($input);
         $validators = [...$this->getClassValidators($reflection), ...$this->getPropertyValidators($reflection)];