Is unresolved reference inspection automatic or custom for each language?

If I have a reference that is `PsiPolyVariantReferenceBase` subclass and its multiresolve returns an empty array, is the unresolved reference error inspection supposed to just work, or do I need to implement my own inspection for my language for it to show up?  I understand that the Quick Fix wouldn't be automatic, but from the comments in the interface, I wasn't able to figure out if I needed to write my own "unresolved reference" inspection.