there are a couple of lines in the Benko gambit accepted where white ends up castling by hand due to exchanging bishops on f1 and recapturing with the king (gets a better pawn structure and removes blacks control of that diagonal, but loses a couple of tempo).
other than that, i can't think of any openings where either side would forfeit castling?
Are there any openings in which white or black deliberately chooses to forfeit castling rights and move the king? Not because of a checking move by the opponent, but because it's actually a good idea for the particular opening. Just wondering.
Thanks.