Symfony 3 will be released at the end of November 2015. Learning from our own history, the transition from Symfony 2 to 3 will be much more pleasant than the transition from symfony 1 to 2 that happened in July 2011.

Technically speaking, Symfony 3 includes no new features comparing it with Symfony 2.8, which will be released at the same time. The main change introduced by Symfony 3 is that any feature, option or behavior marked as deprecated in 2.8 version will be removed.

This means that your Symfony applications won't work on Symfony 3 unless you remove all their deprecations. In order to simplify the task of finding which deprecations affect your applications, a new tool called Deprecation Detector has just been released.

This command console application runs a static code analysis against your project's source code to find usages of deprecated methods, classes, interfaces and services. Specifically, it identifies the use of deprecated code thanks to the @deprecated annotation.

Although this tool is still in a very early stage of development, you can already test it in your own applications:

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$ git clone git@github.com:sensiolabs-de/deprecation-detector.git
$ cd deprecation-detector
$ composer install
$ ./bin/deprecation-detector check /path/to/your-project/src /path/to/your-project/vendor

Tip

Since you are probably going to use this tool very frequently, it's better to build a PHAR file and install it globally, as explained in its documentation.

Deprecation Detector is a project developed by the team at SensioLabs Deutschland, maintained by Marvin Klemp and published as Open Source. Your issues and pull requests are more than welcome to improve the project.