Arrays are serialized as objects like {"0":... } when data contains empty objects

[mrix]

For example this code:

<?php
require __DIR__.'/vendor/autoload.php';

class EmptyClass
{
}
class NotEmptyClass
{
    public $a = 1;
}
class WrapperClass
{
    public $object;

    public function __construct($object)
    {
        $this->object = $object;
    }
}

$objects = [
    'stdClass'      => new stdClass(),
    'ArrayObject'   => new ArrayObject(),
    'EmptyClass'    => new EmptyClass(),
    'NotEmptyClass' => new NotEmptyClass(),
    'DateTime'      => new DateTime(),
];
foreach ($objects as $title => $object) {
    // data to serialize
    $item = [new WrapperClass($object)];
    // serialize
    $json = JMS\Serializer\SerializerBuilder::create()
        ->addDefaultHandlers()
        ->addDefaultSerializationVisitors()
        ->addDefaultDeserializationVisitors()
        ->setCacheDir(__DIR__ . '/runtime')
        ->setDebug(true)
        ->build()
        ->serialize($item, 'json');

    // output
    echo $title.':'.PHP_EOL;
    echo $json.PHP_EOL;
    echo str_repeat('-', 40).PHP_EOL;
}

outputs:

stdClass:
{"0":{"object":{}}}
----------------------------------------
ArrayObject:
{"0":{"object":{}}}
----------------------------------------
EmptyClass:
{"0":{"object":{}}}
----------------------------------------
NotEmptyClass:
[{"object":{"a":1}}]
----------------------------------------
DateTime:
[{"object":"2015-09-07T14:50:34+0600"}]
----------------------------------------

I think this is related to #373

[andreaslarssen]

...which has been closed.