Meta-issue: What hacks could we remove from our checker if we made additional changes upstream?

[cpovirk]

So far, I've opened issues only for changes that I've suspected we absolutely need to make to CF in order to make our checker work.

But there are plenty of places in which our checker could be cleaner (read: less hacky) if we made additional changes to CF. Just to pick the most recent example, I can't imagine that anyone would feel great about how I default type-variable usages only conditionally. Perhaps CF could have native support for this. [update: I backed out my hack because it was -- who could have guessed? :) -- buggy. And I have replaced it with another upstreaming proposal, #7. But the general point stands. To offer a new example, I present another fragile-looking hack.]

But some of our needs make little sense to 99% of CF checkers. So, as with many of the changes we've already made in this CF fork, we may find it hard to argue for supporting them upstream. Still, it would be nice to eventually look into the possibility of replacing hacks with CF changes: Hacks often break somewhere down the line.