1--TEST-- 2Prevent switching fibers in tick function 3--FILE-- 4<?php 5 6declare(ticks=1); 7 8register_tick_function(function (): void { 9 if (Fiber::getCurrent() !== null) { 10 Fiber::suspend(); 11 } 12}); 13 14$fiber = new Fiber(function (): void { 15 echo "1\n"; 16 echo "2\n"; 17 echo "3\n"; 18}); 19 20$fiber->start(); 21 22?> 23--EXPECTF-- 241 25 26Fatal error: Uncaught FiberError: Cannot switch fibers in current execution context in %sticks.php:%d 27Stack trace: 28#0 %sticks.php(%d): Fiber::suspend() 29#1 %sticks.php(%d): {closure}() 30#2 [internal function]: {closure}() 31#3 %sticks.php(%d): Fiber->start() 32#4 {main} 33 thrown in %sticks.php on line %d 34