[php-src] Issue #11743: Seralize incorrectly duplicates element in case of circular reference in array

Issue: https://github.com/php/php-src/issues/11743 Author: IceNV ### Description The following code: ```php <?php $a = ['id'=>1,'parent'=>null,'child'=>null]; $b = ['id'=>2,'parent'=>null,'child'=>null]; $a['child'] =&$b; $b['parent'] = &$a; echo serialize($a); ``` Resulted in this output: ``` a:3:{s:2:"id";i:1;s:6:"parent";N;s:5:"child";a:3:{s:2:"id";i:2;s:6:"parent";a:3:{s:2:"id";i:1;s:6:"parent";N;s:5:"child";R:4;}s:5:"child";N;}} ``` The problem is that in the 'child' array with id 2, 'parent' duplicates the root array with id 1 instead of directly referencing it, something along the lines of : ``` a:3:{s:2:"id";i:1;s:6:"parent";N;s:5:"child";a:3:{s:2:"id";i:2;s:6:"parent";R:1;s:5:"child";N;}} ``` In any case, the parent array shouldn't be duplicated, as this can cause traversal issues or modifications that won't properly propagate if code tries to modify the de-serialized array (for instance modifying element 2's parent will not propagate to the root as it should), for instance : If I modify the original array : ````php $a['id'] = 3; echo($a['id'].','.$a['child']['parent']['id']); ```` echoes (properly) : ```` 3,3 ```` However, if I unserialize the aformentioned string, and apply the same operation, it echoes : ```` 3,1 ```` The reference is lost, as is apparent from the serialized form. (Of course this is a trivial example but corresponds to something I've encountered working with graph-type arrays) ### PHP Version PHP 8.1.21 (FPM,CLI) ### Operating System Debian 10 x64 (on WSL2 on Windows 10 x64) ; Debian 11 x64 (native)