Better Enum diagnostics

[bmewburn]

https://www.php.net/manual/en/language.enumerations.object-differences.php

• [ ] Constructors and Destructors are forbidden.
• [ ] Inheritance is not supported. Enums may not extend or be extended.
• [ ] Static or object properties are not allowed.
• [ ] Cloning an Enum case is not supported, as cases must be singleton instances.
• [ ] Magic methods, except for __call, __callStatic, and __invoke, are disallowed.
• [ ] Enums must always be declared before they are used.
• [ ] enum cases may not be instantiated directly with new