Hey,
Thanks for all the feedback! The RFC is now expanded to explicitly address the concerns on how the optional interfaces interact with type checks, eval'd interfaces, opcache, autoloading, reflection and the Override attribute. Did Did I miss something? Please let me know if anything is still unclear or requires other improvement. https://wiki.php.net/rfc/optional-interfaces I've also polished the implementation and added tests for all the concerns mentioned above. https://github.com/php/php-src/pull/17288 However the implementation is not final as I was not able (yet) to solve how my implementation interacts with the Stringable interface. BR, Juris
