https://wiki.php.net/rfc/typed_properties_v2

PHP's own serializer in ext/standard is a good place to look at to see how unserialization will be affected (That PR doesn't seem to touch the serializer)

• How will unserializers handle unserializing references to properties while supporting that RFC?
• What error handling needs to be done? (When setting property values, when modifying a reference that includes a property value, etc.)
• Look into how the new type uninitialized (of a typed property) is represented (It seems like it is separate from unset or null)