Return the type of the current command-line completion. Only works when the command line is being edited, thus requires use of |c_CTRL-_e| or |c_CTRL-R_=|. See |:command-completion| for the return string. Also see |getcmdtype()|, |setcmdpos()|, |getcmdline()| and |setcmdline()|. Returns an empty string when completion is not defined.