Bug #77566 [Opn->Nab]: void type is not covariant to mixed

Edit report at https://bugs.php.net/bug.php?id=77566&edit=1 ID: 77566 Updated by: cmb@php.net Reported by: Wes dot nospam at example dot org Summary: void type is not covariant to mixed -Status: Open +Status: Not a bug Type: Bug -Package: *General Issues +Package: Scripting Engine problem Operating System: Irrelevant PHP Version: Irrelevant -Assigned To: +Assigned To: cmb Block user comment: N Private report: N New Comment: > void type is not covariant to mixed Right[1]. However, having no return type declaration is not the same as specifying mixed. And the documentation states[2]: | When overriding a parent method, the child's method must match | any return type declaration on the parent. If the parent doesn't | define a return type, then the child method may do so. So, this is a deliberate design decision, mostly for compatibility reasons. [1] <https://3v4l.org/vNF6M> [2] <https://www.php.net/manual/en/language.types.declarations.php> Previous Comments: ------------------------------------------------------------------------ [2019-02-04 14:27:22] Wes dot nospam at example dot org Description: ------------ Going from "has a return value" to "no return value" is certainly not a valid covariant substitution (at least in theory, in practice void is null). The void RFC doesn't cover the case at all. https://wiki.php.net/rfc/void_return_type It is not unlikely that this is currently allowed by accident. Thank you. Test script: --------------- <?php class Foo { public function aaa(){} } class Bar extends Foo { public function aaa(): void{} } Expected result: ---------------- Error Actual result: -------------- No error ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=77566&edit=1