c-go-down-list-forward is a Lisp macro in `cc-defs.el'.

(c-go-down-list-forward &optional POS LIMIT)

Move the point to the first position inside the first list sexp after POS,
or before the point if POS is left out. Return t if such a position
exists, otherwise nil is returned and the point isn't moved.

A limit for the search may be given. The start position is assumed to
be before it.