[RFC] __exists(), a magic method for distinguishing "missing" from "set to null"

Dear internals, It's my pleasure to submit this new RFC to yours. Please have a look and let me know: https://wiki.php.net/rfc/exists-magic-method TL;DR: I'm proposing a new opt-in magic method: public function __exists(string $name): bool; It'd let userland tell "set to null" apart from "missing" on objects, it'd restore isset() <=> ?? equivalence on magic properties, and it'd fixe GH-12695 as a corollary. It's forward-compatible as a regular method on PHP <= 8.5 (probeable via method_exists()), and would be magic on 8.6+. Cheers, Nicolas