You are browsing the documentation for Symfony 3.4 which is not maintained anymore.
Consider upgrading your projects to Symfony 5.2.
The Symfony Polyfill / PHP 7.1 Component
The Symfony Polyfill / PHP 7.1 Component¶
This component provides some PHP 7.1 features to applications using earlier PHP versions.
$ composer require symfony/polyfill-php71
If you install this component outside of a Symfony application, you must
vendor/autoload.php file in your code to enable the class
autoloading mechanism provided by Composer. Read
this article for more details.
This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.