Debian's php-elisp package has not been updated last since 1.13.5. This is the version released in July 2014.

• https://packages.debian.org/jessie/php-elisp
• https://packages.debian.org/sid/php-elisp

This version does not yet support PHP 7 syntax, so it is not suitable for modern PHP code editing.
We may need to contact the Debian package maintainer team.