Regression test

Closes phpstan/phpstan#9204

Author: ondrejmirtes

tests/PHPStan/Analyser/nsrt/bug-9204.php

@@ -0,0 +1,37 @@
+<?php declare(strict_types = 1);
+
+namespace Bug9204;
+
+use function PHPStan\Testing\assertType;
+
+function (): void {
+	$goodObject = (new class() {
+		/**
+		 * @var array<string, mixed>
+		 */
+		private array $properties;
+
+		/**
+		 * @param array<string, mixed> $properties
+		 */
+		public function __construct(array $properties = [])
+		{
+			$this->properties = $properties;
+		}
+		public function __isset(string $offset): bool
+		{
+			return isset($this->properties[$offset]);
+		}
+		public function __get(string $offset): mixed
+		{
+			return $this->properties[$offset] ?? null;
+		}
+	});
+	$objects = [
+		new $goodObject(['id' => 42]),
+		new $goodObject(['id' => 1337]),
+	];
+
+	$columns = array_column($objects, 'id');
+	assertType('list', $columns);
+};