--TEST-- Classes can only be used once they are fully linked --FILE-- <?php spl_autoload_register(function($class) { echo new ReflectionClass(A::class), "\n"; }); class A implements I { } ?> --EXPECTF-- Fatal error: Uncaught ReflectionException: Class "A" does not exist in %s:%d Stack trace: #0 %s(%d): ReflectionClass->__construct('A') #1 %s(%d): {closure}('I') #2 {main} thrown in %s on line %d