Bug #50892 [Com]: Protected members of non-congruent children classes are visible

Edit report at https://bugs.php.net/bug.php?id=50892&edit=1 ID: 50892 Comment by: rowan dot collins at gmail dot com Reported by: EdwardDrapkin at gmail dot com Summary: Protected members of non-congruent children classes are visible Status: Open Type: Bug Package: Class/Object related Operating System: Irrelevant PHP Version: 5.3.1 Block user comment: N Private report: N New Comment: This may seem odd, but is actually perfectly reasonable if you consider polymorphism: - Access is class-based, not instance-based: you can call private members of a different instance of the same class. - For the same reason, you can access protected members on an instance of a parent class. - If you ask for an instance of class A, you may at run-time actually receive an instance of some sub-class of A. - So, if classes B1 and B2 both inherit from A, a method on class B1 might ask for an instance of A, and be given an instance of B2; when it calls a method on that instance, it's the definition in B2 which will be accessed. Here's a concrete example: https://3v4l.org/LeClo Note that this example also works in Java: https://tio.run/##vZMxb9swEIVn61fcKKctbWctMhUIuhgomqIdigwn8mIxpUiDPNkpDP92hxJlW4rsIUBRQhP5@O670@MzbvDTs/pzOGAR2KNkkAZDgG9eS4JdBnGtvWOSTAqUqwtDsEFT0@f2LAnirpbpTt7XTDuHZnGpg2h34a7vsD/7nBhGFVfE33H7s7mVT8eVz6p75yvkeLPT9gBmM/iCxgTAnn9FXDoF7gm2pZYlbciDLLVR3Rx0aMFPJp649haWyKXwrrYqb/sa8E1HjXWYG6cVoFJ5mq7jkvy/IGyNLg36w106Exfmt8/2WZYsfuDLvSdKVPTCZNWbBCT@ge7qjw71mnyeto@lLudoQNVz6IZ8bmRE3CL80lxGpCHxbpTIo@x/AsMNLMRtDzvriBL@ErWN1yfdZmDkYzyqeJQ/sNd29fsR0K9CU2gySUPH@HYsbQd/Il/MxTyCHzVFp@k3f9Y8/A1MlXA1i3UswsbmKC48nGvi4qo4fjHAX8nTR0AL2sa2bBPzp2FwttoYQCkpvA16VcRsR3mfPLqiaN5M8W78ZvCHwys The example from the original report also works in Java: https://tio.run/##fY9BDoMgEEXXcgriShflAqZH6Mpl0zSg1CAKDYy2TePZKQTUpovuZv7/mf@mpzM99K10rhmotfimNX6j7D6xQTS4BiNUh69pPeKc5lXmbaOBN8DbPbEpPrQteYUWhOJlRg3mT@Cq3Vp2U4r210yds/YWcAtFGdQsuMyXKP4IJ4uy8mL9ssBHoicgd88DgyoYSdT/AitnyCyBJpVGqBMV6ovEAoUVaPRWEX8/XzA1nY104Q@Z6Pwc6SSJ/KnEuQ8 I'm of the opinion that this is not a bug. Previous Comments: ------------------------------------------------------------------------ [2017-07-21 18:42:58] cmb@php.net Related To: Bug #74932 ------------------------------------------------------------------------ [2017-02-22 09:32:30] mail at pmmaga dot net A PR was prepared to fix this on the current master (7.2) but it was decided the the potential BC break could possibly be too much for a minor and it was suggested that it should wait for the next major. ------------------------------------------------------------------------ [2016-03-27 16:16:02] nikic@php.net Related To: Bug #69766 ------------------------------------------------------------------------ [2015-09-08 00:38:08] cmb@php.net | There is no design ground to accept that, it is a bug. The | question that remains is: is it worth to fix BC-wise? IMHO the question is rather: when is the BC break acceptable? 7.1 or 8.0? ------------------------------------------------------------------------ [2015-03-10 08:53:17] arth dot inbox at gmail dot com normandiggs, your sample is irrelevant. It's ok to access private and protected properties from same type object. It's bad to access protected properties from different type object. Why I hate this behavior: http://3v4l.org/tiOC5 - we receive protected value http://3v4l.org/uT9PC - we receive fatal error We should not to rely to implementation of B class (see fiddles) Another note - this behavior was broken in 5.2 version. ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at https://bugs.php.net/bug.php?id=50892 -- Edit this bug report at https://bugs.php.net/bug.php?id=50892&edit=1