Upgrade Symfony dependency to 3.x
The Ubuntu/Debian community have raised the issue that the 2.x version of Symfony used by CiviCRM is quickly going to be outdated.
nacc on IRC recommended moving to 3.x.
2018-02-12 13:11 < nacc> Apologies for what might be considered offtopic; I work on Ubuntu Server, and am responsible for our current migration to PHP7.2 (from PHP7.1). One of the fallouts was a move to Symfony 3.4.3, which in turns breaks CiviCRM which is incompatible with 3.0 per composer.json. Is this a hard (and not likely to change) dependency, and should we therefor remove civicrm from Ubuntu? 2018-02-12 13:16 < nacc> [...] our feature freeze is March 1. I will note as well that civicrm is uninstallable in Debian for the same reason (the Debian pacakge, that is): https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=883640
@jackrabbithanna mentioned on Mattermost:
Actually CiviCRM Core is behind Drupal 8, so upgrading it would be super
D8 either is or will be using Symfony 3.2.8 (was/is 3.2.6)
anyway, 8.4 definitely is Symfony 3.2