We were initially aiming to support php7 in Moodle 3.1 but then decided
to make a "Christmas present" to our users and backport all necessary
changes to Moodle 3.0. Everybody anticipates that php7 will immediately
become very popular because of its performance indicators, we also know
that many institutions have not even upgraded to Moodle 3.0 yet, it will
still be supported for a long time and users can really benefit from
The current plan
is to dedicate this week to integration and testing only of
php7-related issues. We have already achieved 100% pass on automated
tests (phpunit and behat) and are currently running a mini QA cycle on
both php5 and php7. If everything goes well (which is very-very likely),
we will release 3.0.1 on Monday December 21st, 2015.
You don't need to immediately upgrade, there will be no security issues in this release. The next point release with security fixes will happen, as usual, on January 11th, 2016.
Feel free to participate in discussions and testing, please report any php7-related issues that you find under the epic MDL-50565.
There is also some documentation to help you upgrade your plugins.
Merry Christmas and Happy New Year!