Description:
------------
PHP 7.3.8RC1 (and 7.4snapshot) emits notices after I update symfony/var-dumper to v4.3.3 today.

"zvalIsRef in vendor\symfony\var-dumper\Cloner\VarCloner.php on line 268"

The variable "zvalIsRef" around VarCloner.php on line 268 is actually obviously defined. So I have much confidence this is a PHP engine's problem.

After some tests, this seems to be the problematic commit https://github.com/php/php-src/commit/e7a83ec8dff962ea624508f18b9b10f5add030cc . It's parent 3fa9f9cfae2cedd7b6d26b6487dd156321243ab7 works fine in my test.

I am sorry that I am not able to give a smaller test case.


Test script:
---------------
<?php

declare(strict_types=1);

// remember to set opcache.enable_cli=1 if this test is done in cli
// composer require symfony/var-dumper:v4.3.3
require __DIR__ . '/vendor/autoload.php';

use Symfony\Component\VarDumper\Cloner\VarCloner;

$myVar = new ArrayObject();
$cloner = new VarCloner();
$data = $cloner->cloneVar($myVar);


Expected result:
----------------
no notice is emitted.

Actual result:
--------------
Notice: Undefined variable: zvalIsRef in vendor\symfony\var-dumper\Cloner\VarCloner.php on line 268

Notice: Undefined variable: zvalIsRef in vendor\symfony\var-dumper\Cloner\VarCloner.php on line 268