1--TEST--
2GH-16408: Array to string conversion warning emitted in optimizer
3--FILE--
4<?php
5$counter = 0;
6ob_start(function ($buffer) use (&$c, &$counter) {
7 $c = 0;
8 ++$counter;
9}, 1);
10$c .= [];
11$c .= [];
12ob_end_clean();
13echo $counter . "\n";
14?>
15--EXPECT--
163
17
