In VarDumper's VarCloner, we use some black magic tricks to work with PHP references (called "hard references" in the code, i.e. $b = &$a).

In PHP 7.4, this will break with typed properties, because of the $cookie trick that is used to detect these references.

But PHP 7.4 has a solution: ReflectionReference

So, when PHP 7.4 is used, we can replace the current implementation by one based on ReflectionReference. That would make things both cleaner and compatible with typed-references.

While this might not be the most trivial part of the code to have a look at, the ETA of PHP 7.4 is early December. Anyone would like to give it a try?