comment-search-backwardcomment-search-backward is a compiled Lisp function in `
(comment-search-backward &optional LIMIT NOERROR)
Find a comment start between LIMIT and point.
Moves point to inside the comment and returns the position of the
comment-starter. If no comment is found, moves point to LIMIT
and raises an error or returns nil if NOERROR is non-nil.
Ensure that `comment-normalize-vars' has been called before you use this.