AssignArrayToStringRector

String cannot be turned into array by assignment anymore

-$string = '';
+$string = [];
 $string[] = 1;

Configure your rector.php:

<?php

use Rector\Config\RectorConfig;
use Rector\Php71\Rector\Assign\AssignArrayToStringRector;

return RectorConfig::configure()
    ->withRules([
        AssignArrayToStringRector::class,
    ]);
SETS:  PHP 7.1