1--TEST-- 2ob_start(): Ensure unerasable buffer cannot be erased by ob_clean(), ob_end_clean() or ob_end_flush(). 3--FILE-- 4<?php 5function callback($string) { 6 static $callback_invocations; 7 $callback_invocations++; 8 return "[callback:$callback_invocations]$string\n"; 9} 10 11ob_start('callback', 0, false); 12 13echo "All of the following calls will fail to clean/remove the topmost buffer:\n"; 14var_dump(ob_clean()); 15var_dump(ob_end_clean()); 16var_dump(ob_end_flush()); 17 18echo "The OB nesting will still be 1 level deep:\n"; 19var_dump(ob_get_level()); 20?> 21--EXPECTF-- 22[callback:1]All of the following calls will fail to clean/remove the topmost buffer: 23 24Notice: ob_clean(): failed to delete buffer of callback (0) in %s on line 11 25bool(false) 26 27Notice: ob_end_clean(): failed to discard buffer of callback (0) in %s on line 12 28bool(false) 29 30Notice: ob_end_flush(): failed to send buffer of callback (0) in %s on line 13 31bool(false) 32The OB nesting will still be 1 level deep: 33int(1)