[Checkers] BasicChecker Question

[Matt Papi]

> Does the Flow class operate on non-polymorphic types only?

There's no limitation in Flow that prevents it from working on
polymorphic qualifiers. However, I did have issues due to the
polymorphism implementation, which is why I added that restriction. I
didn't address them at the time because my case study was top priority
and it didn't require flow-sensitive polymorphic qualifiers. In any
case, those issues might be merely historical now (but I haven't
checked).

On a related note, in the long run it might be worthwhile to replace
the polymorphism implementation with IGJ's @I implementation (or
something based on it), which would both improve polymorphism (e.g.
with class/field support) and could shorten the IGJ checker (and maybe
the Javari checker as well).

- Matt