Enable typing in rubocops

[dduugg]

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes? Here's an example.
• Have you successfully run brew style with your changes locally?
• Have you successfully run brew typecheck with your changes locally?
• Have you successfully run brew tests with your changes locally?

---

This changes enables typing for everything under Library/Homebrew/rubocops.

The most significant change here is probably enabling --enable-experimental-requires-ancestor flag in sorbet. Since the feature "is experimental and might be changed or removed without notice", i've put every use of requires_ancestror in an rbi file, so that the runtime does depend on a potentially breaking change. (However, since sorbet-runtime appears to be vendored, this may be overkill.)

[BrewTestBot]

Review period will end on 2023-02-16 at 18:40:07 UTC.

[MikeMcQuaid]

Thanks again @dduugg!

[BrewTestBot]

Review period ended.

[dduugg]

This PR revealed an interesting design artifact. It seems FormulaCop is intended to be a sort of abstract super class for formulae cops, but rubocop has been running as a cop itself all along. This wasn't noticed before, because its on_class handler would early exit due to the lack of an audit_formula method.

However, sorbet doesn't allow FormulaCop to invoke audit_formula without it being defined in the class (and sorbet doesn't support respond_to? guards, because it can't check the method param/return types, perform an arity check, etc.). Thus I defined a pseudo-abstract audit_formula method in FormulaCop, which raises a NotImplementedError (I can't just mark the class and method abstract due to how rubocop instantiates Cop subclasses).

I've worked around the issue for now by disabling FormulaCop in .rubocop.yml (its subclasses remain enabled), with a note to convert it to interface. Other solutions could include having audit_formula no-op in FormulaCop rather than raising a NotImplementedError, or creating an interface for the audit_formula method that FormulaCop subclasses are required to implement. I don't like these approaches as much though, because they maintain FormulaCop as Cop for rubocop to run, which I don't think is the intention.

[Bo98]

Yeah I did redo the FormulaCop stuff before to be a Force rather than a Cop but there were a lot of changes to rubocops at the time that it meant conflicts were frequent (and I needed to make changes in other taps because of the slight behavioural changes), plus there was hesitation against such a large refactor. Maybe worth revisiting again at some point on some quiet week.