Bug #62814 [Nab]: It is possible to stiffen child class members visibility

Edit report at https://bugs.php.net/bug.php?id=62814&edit=1 ID: 62814 Updated by: rasmus@php.net Reported by: resha dot ru at gmail dot com Summary: It is possible to stiffen child class members visibility Status: Not a bug Type: Bug Package: Class/Object related Operating System: Linux PHP Version: 5.3.15 Block user comment: N Private report: N New Comment: Johannes, I think you are actually agreeing with him here. As per Liskov you can't tighten visibility, you can only loosen it on inheritance. However, in this case you aren't tightening it because the original was private, so setting it back to private is allowed and doesn't violate Liskov. Previous Comments: ------------------------------------------------------------------------ [2012-08-23 21:28:49] johannes@php.net If you'd stiffen visibility you'd be violating the is-a contract given. If an object is using a classed derived from A and I can do "instanceof A" I expect to be able to call all methods from A and having them do something like A's method does. When stiffening that won't be the case anymore. ------------------------------------------------------------------------ [2012-08-23 19:49:18] kev dot simpson at gmail dot com I reported this same problem a few years ago here: https://bugs.php.net/bug.php?id=48376 I was told this was not a bug (although I haven't a clue as to why its not deemed as such). I believe C# allows you the ability to do this as it would resolve up the scope, but as of 5.4.0 I still cannot get why it allows forced reduced scopes during declaration, but provides an uncatchable fatal error on call. I'm still most concerned by the allowed reduction from an interface. There is no way to guarantee that an interface will implement the method in question regardless of if it is known to be that type which truly is a shame. ------------------------------------------------------------------------ [2012-08-14 09:50:47] resha dot ru at gmail dot com Sorry, it should be: class F extends D { private function test() { } // stiffen visibility from public to private (unexpected) } But nevertheless. ------------------------------------------------------------------------ [2012-08-14 09:48:17] resha dot ru at gmail dot com Description: ------------ It is possible to stiffen visibility (from public to protected, from public to private and from protected to private) if any of parent classes has private modifier. Test script: --------------- class A { private function test() { } } class B extends A { protected function test() { } // loosen visibility from private to protected (expected) } class C extends B { private function test() { } // stiffen visibility from protected to private (unexpected) } class D extends B { public function test() { } // loosen visibility from protected to public (expected) } class E extends D { protected function test() { } // stiffen visibility from public to protected (unexpected) } class F extends B { private function test() { } // stiffen visibility from public to private (unexpected) } Expected result: ---------------- PHP Fatal error: Access level to C::test() must be protected (as in class B) or weaker Actual result: -------------- Everything is ok. ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=62814&edit=1