Lint if a field overrides a superclass field

[stereotype441]

E.g.

class C {
  var f;
}
class D extends C {
  var f; // LINT
}
class E implements C {
  var f; // OK
}

A lint warning me that I was overriding a superclass field would have saved me about two hours of debugging today :)

[a14n]

I just tested and this is catched by overridden_fields rule.

[pq]

@stereotype441 : was this in the analyzer code base?

Incidentally, I take the fact that there is a rule that would catch this to be another case in point for the "we should really have a set of lint rules defined so that projects can easily derive from them" conversation (#288).

[stereotype441]

@pq it was in pkg/front_end in the SDK repo.

[pq]

/cc @davidmorgan as this is a good Google ruleset consideration.

A topic for another issue elsewhere, but @stereotype441, @bwilkerson, it might be interesting to consider updating options for front_end, kernel, analyzer and server to at least derive from the evolving google ruleset.

But anyway, lets close this in favor of picking that up elsewhere if there's interest.

Thanks!

[davidmorgan]

Noted. Thanks!