get_cb_alias was introduced in 2.14 and referencing it directly in this macro breaks compilation against libpurple-2.13, as found in Debian Buster. https://docs.pidgin.im/pidgin/2.x.y/struct__PurplePluginProtocolInfo.html#ad43cef005f1634b0d170cc2972c69550
This code comes from https://github.com/Flared/purple-icq/tree/master/src/purple It is GPL-3 licensed