A few days ago I merged a patch into Xdebug that removes support for PHP 5 in Xdebug's master branch on GitHub. Maintaining PHP 5 and PHP 7 support in one code base is not particularly easy, and even more complicated for something like Xdebug, with its deep interactions with PHP's internals.
As PHP 5.6's active support has ended on December 31st, I also felt it no longer needed to support PHP 5 with Xdebug any more. It saves more than 5000 lines of code:
Many people people were quite positive about that:
Others were less keen:
Removing PHP 5 support from Xdebug's master branch does not mean that Xdebug suddenly stops working for PHP 5 installations. Xdebug 2.5, which was recently released supports PHP 5.5 and 5.6, and is not going to go away.
Right now, Xdebug will no longer receive new features in the branch that also supports PHP 5. New features will only go into master (to become Xdebug 2.6). However, Xdebug 2.5 continues to receive bug fixes until Xdebug 2.6 comes out.
Once Xdebug 2.6 comes out, the Xdebug 2.5 branch will no longer get bug fixes, and hence support for PHP 5 goes away. That still does not mean that you can no longer use Xdebug with PHP 5. The releases of the 2.5 branch will still be available.
On the positive side, not having to implement lots of code twice, also means that new features can be added faster, as less work is required. Xdebug 2.6 has already have some new features lined up.