Merge pull request #505 from mglaman/gh499

Author: mglaman

stubs/Drupal/Core/Field/FieldItemList.stub

@@ -0,0 +1,15 @@
+<?php
+
+namespace Drupal\Core\Field;
+
+use Drupal\Core\TypedData\Plugin\DataType\ItemList;
+
+class FieldItemList extends ItemList implements FieldItemListInterface {
+
+  /**
+   * @return \Drupal\Core\Field\FieldItemInterface
+   */
+  protected function createItem($offset = 0, $value = NULL): \Drupal\Core\Field\FieldItemInterface {
+  }
+
+}

tests/src/Type/EntityTypesTest.php

@@ -14,6 +14,7 @@ final class EntityTypesTest extends TypeInferenceTestCase
     public function dataFileAsserts(): iterable
     {
         yield from $this->gatherAssertTypes(__DIR__ . '/data/entity-type-stubs.php');
+        yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-499.php');
     }
 
     /**

tests/src/Type/data/bug-499.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace Bug499;
+
+use Drupal\Core\Field\FieldItemList;
+use Drupal\Core\TypedData\ComputedItemListTrait;
+use function PHPStan\Testing\assertType;
+
+class ComputedFieldItemList extends FieldItemList {
+    use ComputedItemListTrait;
+
+    protected function computeValue()
+    {
+        $item = $this->createItem(0, 'foo');
+        assertType('Drupal\Core\Field\FieldItemInterface', $item);
+        $this->list[0] = $item;
+    }
+}