Literal types RFC

Hello internals, Since union types have landed in PHP, this allows us the possibility to have literal types support as well and I would like to hear your thoughts about an RFC for it. I think a feature like this would greatly improve the way we model our code in very common use cases. For example, let's consider having a function that returns the status of a post. ```php /** /** @return "draft"|"published" */ function getStatus(): string { } ``` Would become ```php function getStatus(): "draft" | "published" { } ``` Of course this could become quite messy if there are more than a few literal types, in which case separate RFCs could be created for type aliases and valueof/keyof features. I would also like to mention that I also worked on a basic implementation for the first phase of the implementation; it's nowhere near to be completed, but I think I can finish it with some guidance/help from you. Regards, Bogdan Ungureanu