vapi:

    [Compact, CCode (cname = "AC_AUTOMATA", cheader_filename = "ahocorasick/aho_corasick.h", free_function = "ac_automata_release")]
    public class Automata {
        public Automata ();

        [Compact, CCode (cname = "ac_automata_init", has_target = false )]
        public void init (AC.Callback mc);
    }


.vala:

var aca = new AC.Automata ();
aca.init (match_handler);


Output:
/home/ava/develop/vala/xmlprocess/test.vala:35: undefined reference to `ac_automata_new'

35: the line with "new .. "