Franz oh, uh actually I got the library to work on a lower version. (heh, seemed like the easier course of action, since it's quite a lot smaller than Flarum Core, and I'll doubtless be making pull requests to it.) I'll admit that that's really just a kludge for development.
But yeah, upgrading Symfony would be the more sustainable solution, so I suppose I'll get to work on that at some point before beta on my extension. Unless someone else is dying to do it first.
I guess I assumed that this was the sort of thing that got talked in committee before you just do it. Symfony doesn't seem terribly interested in backwards compatibility (at least by glancing at these packages) so I'd imagine upgrading would break things.
