Is this complement for subject or verb?

[eipjoo]

My feet they are sore, and my limbs they are weary;
Long is the way, and the mountains are wild;
Soon will the twilight close moonless and dreary
Over the path of the poor orphan child. (Jane Eyre)

Ought the highlighted be called complement for subject, or complement for verb?

[Frank Antonson]

That's a pretty good question. It is a lot like "The gate swung shut", which was thoroughly discussed here.

But, to make it easy, I would say that the words "and it will be" are understood, in which case would be ellipsis and "moonless and dreary" would be , in R-K terms, a compound predicate adjective -- one of the SUBJECT complements.