The Master Zend Framework site has posted a new tutorial for those making the move in their legacy applications up to the world of PHP 7. In it Matthew Setter shows how to use phan, a static analysis tool, to locate issues that could cause breakage in the upgrade.

Unless you’ve been living under a rock these last 12 - 18 months, you will have heard about PHP 7; the latest version of PHP. Not only is it fast, by some reports it’s up to twice as fast as PHP 5.6, and far less memory hungry.

[...] Unfortunately, your application’s source code may not be 100% compatible with version 7. Upgrading may well leave you with a broken application and a set of unhappy customers. So before you go breaking your site in the interests of speed and being one of the cool kids, find out if your code’s compatible. How? By using a static code analyser, one which gives you all the changes you need to make on your code, so that you can upgrade with confidence.

He then shows how to install the Phan tool via Composer and execute it against your codebase. The result of his commands are a file that contains the issues found during the scan. If there are some "false positives" you'd like to ignore he also shows you how to create a config.php file with these and other values set to make it all more reusable.