Heroku Changelog Simultaneous use of HHVM and PHP runtimes

Change effective on 21 May 2014

Heroku’s PHP support beta now allows the explicit declaration of both hhvm and php as dependencies in composer.json.

During a deploy, only the requested runtime(s) will be installed, so if you require regular PHP in addition to HHVM for any reason, make sure it’s specified appropriately.

If HHVM is declared as a dependency, Composer installs will be executed using HHVM to satisfy the dependency requirement. HHVM identifies itself as PHP version “5.5.99” when queried using phpversion() or in PHP_VERSION constants.