Use PHP 7.1 features : is_iterable, ?? and ?:

[GromNaN]

Apply the following changes with rector, compatible with PHP 7.1:

return static function (RectorConfig $rectorConfig): void {
    $rectorConfig->paths([
        __DIR__ . '/src',
        __DIR__ . '/doc',
        __DIR__ . '/tests',
        __DIR__ . '/extra',
    ]);
    $rectorConfig->rule(\Rector\Php53\Rector\Ternary\TernaryToElvisRector::class);
    $rectorConfig->rule(\Rector\Php70\Rector\Ternary\TernaryToNullCoalescingRector::class);
    $rectorConfig->rule(\Rector\Php71\Rector\BooleanOr\IsIterableRector::class);
};

[GromNaN]

You may want to switch to ::class constant for all referenced class names.

    $rectorConfig->rule(\Rector\Php55\Rector\String_\StringClassNameToClassConstantRector::class);

[fabpot]

We don't update 2.x anymore except for bug fixes. Can you retarget on 3.x?

[GromNaN]

Also replaced calls to twig_test_iterable with is_iterable. The function twig_test_iterable is deprecated to be removed in 4.0.

[fabpot]

Thank you @GromNaN.