--TEST-- The same rules are applied for properties that are defined in the class hierarchy. Thus, if the properties are compatible, a notice is issued, if not a fatal error occures. --FILE-- <?php error_reporting(E_ALL | E_STRICT); class Base { private $hello; } trait THello1 { private $hello; } echo "PRE-CLASS-GUARD\n"; class Notice extends Base { use THello1; private $hello; } echo "POST-CLASS-GUARD\n"; // now we do the test for a fatal error class TraitsTest { use THello1; public $hello; } echo "POST-CLASS-GUARD2\n"; $t = new TraitsTest; $t->hello = "foo"; ?> --EXPECTF-- PRE-CLASS-GUARD POST-CLASS-GUARD Fatal error: TraitsTest and THello1 define the same property ($hello) in the composition of TraitsTest. However, the definition differs and is considered incompatible. Class was composed in %s on line %d