[validator] add ConstraintViolationListInterface.stubphp (#222)

Author: vudaltsov

src/Stubs/common/Component/Validator/ConstraintViolationListInterface.stubphp

@@ -0,0 +1,10 @@
+<?php
+
+namespace Symfony\Component\Validator;
+
+/**
+ * @extends \Traversable<int, ConstraintViolationInterface>
+ */
+interface ConstraintViolationListInterface extends \Traversable, \Countable, \ArrayAccess
+{
+}

tests/acceptance/acceptance/ConstraintViolationListInterface.feature

@@ -0,0 +1,28 @@
+@symfony-common
+Feature: ConstraintViolationListInterface
+
+  Background:
+    Given I have Symfony plugin enabled
+
+  Scenario: ConstraintViolationListInterface is a Traversable with int key and ConstraintViolationInterface value
+    Given I have the following code
+      """
+      <?php
+
+      use Symfony\Component\Validator\ConstraintViolationListInterface;
+
+      function run(ConstraintViolationListInterface $list): void
+      {
+          foreach ($list as $key => $value) {
+              /** @psalm-trace $key */
+              echo $key;
+              /** @psalm-trace $value */
+          }
+      }
+      """
+    When I run Psalm
+    Then I see these errors
+      | Type  | Message                                                          |
+      | Trace | $key: int                                                        |
+      | Trace | $value: Symfony\Component\Validator\ConstraintViolationInterface |
+    And I see no other errors