In the sentence
I think the desire to be smart is a normal thing.
what part of speech is "smart" regarding the infinitive "to be"? Is it a direct object, complex subject or something else?
As I know, an adjective can't be direct object at all (and to be isn't a transitive verb but a linking one, so it's can't have a direct object even in a theory) nor an subject complement if "to be" isn't a predicate in the context mentioned above. So, what role has "smart" in the sentence?