Wrongly narrowed types in assertSame

tests/Type/PHPUnit/AssertFunctionTypeSpecifyingExtensionTest.php

@@ -20,6 +20,8 @@ public static function dataFileAsserts(): iterable
 			yield from self::gatherAssertTypes(__DIR__ . '/data/assert-function-9.6.11.php');
 		}
 
+		yield from self::gatherAssertTypes(__DIR__ . '/data/bug-14279.php');
+
 		return [];
 	}
 

tests/Type/PHPUnit/data/bug-14279.php

@@ -0,0 +1,99 @@
+<?php declare(strict_types=1);
+
+namespace Shopware\Tests\Unit\Core\Framework\Struct;
+
+use PHPUnit\Framework\TestCase;
+use function PHPStan\Testing\assertType;
+
+/**
+ * @internal
+ */
+class CollectionTest extends TestCase
+{
+	public function testFromAssociative(): void
+	{
+		$data = [
+			null,
+			0,
+			'some-string',
+			new \stdClass(),
+			['some' => 'value'],
+		];
+
+		$collection = (new TestCollection())->assignRecursive($data);
+
+		static::assertCount(5, $collection);
+
+		assertType("array{null, 0, 'some-string', stdClass, array{some: 'value'}}", $data);
+		static::assertSame($data[0], $collection->get(0));
+		assertType("array{null, 0, 'some-string', stdClass, array{some: 'value'}}", $data);
+		static::assertSame($data[1], $collection->get(1));
+		assertType("array{null, 0, 'some-string', stdClass, array{some: 'value'}}", $data);
+		static::assertSame($data[2], $collection->get(2));
+		assertType("array{null, 0, 'some-string', stdClass, array{some: 'value'}}", $data);
+		static::assertSame($data[3], $collection->get(3));
+		assertType("array{null, 0, 'some-string', stdClass, array{some: 'value'}}", $data);
+		static::assertSame($data[4], $collection->get(4));
+		assertType("array{null, 0, 'some-string', stdClass, array{some: 'value'}}", $data);
+	}
+}
+
+/**
+ * @template TElement
+ *
+ * @extends Collection<TElement>
+ */
+class TestCollection extends Collection
+{
+}
+
+/**
+ * @template TElement
+ *
+ * @implements \IteratorAggregate<array-key, TElement>
+ */
+abstract class Collection implements \IteratorAggregate, \Countable
+{
+	/**
+	 * @var array<array-key, TElement>
+	 */
+	protected array $elements = [];
+
+	/**
+	 * @param iterable<TElement> $elements
+	 */
+	public function __construct(iterable $elements = [])
+	{
+	}
+
+	/**
+	 * @param array-key $key
+	 *
+	 * @return TElement|null
+	 */
+	public function get($key)
+	{
+		return $this->elements[$key] ?? null;
+	}
+
+	/**
+	 * @phpstan-impure
+	 */
+	public function count(): int
+	{
+		return \count($this->elements);
+	}
+
+	/**
+	 * @return \Traversable<TElement>
+	 */
+	public function getIterator(): \Traversable
+	{
+		yield from $this->elements;
+	}
+
+	public function assignRecursive(array $options): static
+	{
+		return $this;
+	}
+}