Bug #76973 [Opn->Asn]: Return type that is alias of base class' type should be compatible

Edit report at https://bugs.php.net/bug.php?id=76973&edit=1 ID: 76973 Updated by: nikic@php.net Reported by: ayg at aryeh dot name Summary: Return type that is alias of base class' type should be compatible -Status: Open +Status: Assigned Type: Bug Package: Scripting Engine problem Operating System: Ubuntu PHP Version: 7.2.10 -Assigned To: +Assigned To: levim Block user comment: N Private report: N New Comment: Long term this is going to be implicitly solved by proper variance support, but for now it might make sense to handle this the same way we do for argument types, i.e. load the classes if they do not pass the string equality checks, but only allow exact matches (no variance). @levim: What do you think about this? Previous Comments: ------------------------------------------------------------------------ [2018-10-04 17:59:15] nikic@php.net Comment by spam2 at rhsoft dot net deleted. It was rude, without contributing technical insight wrt this issue. ------------------------------------------------------------------------ [2018-10-04 17:26:14] ayg at aryeh dot name Description: ------------ If a base class defines a method with a return type declaration, and a derived class overrides the method, the return type in the derived class must be the same as in the base class. However, if the return types are classes that are aliases of one another, it should be considered the same. Currently it is not. Test script: --------------- <?php class A {} class_alias( "A", "B" ); class C { function f() : A { return new A; } } class D extends C { function f() : B { return new B; } } Expected result: ---------------- No error Actual result: -------------- PHP Fatal error: Declaration of D::f(): B must be compatible with C::f(): A in Standard input code on line 5 ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=76973&edit=1