Took a stab at making some sense out of this... turned out to be easier to look at the git log from 3.5.4 to master than staring at the meaningless diff of alpm.h. I think I've got the majority of it, but feel free to point out where I've missed anything. Backwards compat is for suckers! d API CHANGES BETWEEN 3.5 AND 4.0 =============================== [REMOVED] - error codes: PM_ERR_LIBFETCH, PM_ERR_WRITE - alpm_option_set_root(), alpm_option_set_dbpath() - alpm_list_first() - alpm_grp_get_name(), alpm_grp_get_pkgs() - alpm_delta_get_from(), alpm_delta_get_to(), alpm_delta_get_filename(), alpm_delta_get_md5sum(), alpm_delta_get_size() - alpm_miss_get_target(), alpm_miss_get_dep(), alpm_miss_get_causingpkg() - alpm_dep_get_mod(), alpm_dep_get_name(), alpm_dep_get_version() - alpm_conflict_get_package1(), alpm_conflict_get_package2(), alpm_conflict_get_reason() - alpm_fileconflict_get_target(), alpm_fileconflict_get_type(), alpm_fileconflict_get_file(), alpm_fileconflict_get_ctarget() - alpm_db_get_url() [CHANGED] - PM_ prefixes for enum values are now ALPM_ - pm prefixes for structs and enums are now alpm_ - alpm_initialize now has parameters: char *root, char *dbpath, _alpm_errno_t *err and returns an alpm_handle_t struct. - alpm_release now takes an alpm_handle_t *. - alpm_db_register_sync() now requires a extra parameter of a alpm_siglevel_t. - alpm_pkg_load() now requires an extra parameter of an alpm_siglevel_t - alpm_db_setserver() replaced by alpm_db_set_servers(), alpm_db_add_server(), alpm_db_remove_server() - many functions now require a first parameter of an alpm_handle_t *: - alpm_option_get_* - alpm_option_set_* - alpm_option_add_* - alpm_option_remove_* - alpm_trans_* - alpm_add_pkg - alpm_checkconflicts - alpm_checkdeps - alpm_db_register_sync - alpm_db_set_pkgreason - alpm_db_unregister_all - alpm_fetch_pkgurl - alpm_find_dbs_satisfier - alpm_logaction - alpm_pkg_load - alpm_release - alpm_remove_pkg - alpm_sync_sysupgrade - several structs are no longer opaque - alpm_conflict_t - alpm_delta_t - alpm_depend_t - alpm_depmissing_t - alpm_depmod_t - alpm_fileconflict_t - alpm_group_t - alpm_pkg_reason_t [ADDED] - package signing functions: alpm_option_get_default_siglevel(), alpm_option_set_default_siglevel(), alpm_option_get_gpgdir(), alpm_option_set_gpgdir(), alpm_db_get_siglevel(), alpm_sigresult_cleanup(), alpm_db_check_pgp_signature(), alpm_pkg_check_pgp_signature() - list functions: alpm_list_to_array(), alpm_list_previous() - structs: alpm_backup_t, alpm_file_t, alpm_filelist_t - enums: alpm_siglevel_t, alpm_sigstatus_t, alpm_sigvalidity_t - error codes: ALPM_ERR_DB_INVALID, ALPM_ERR_DB_INVALID_SIG, ALPM_ERR_GPGME, ALPM_ERR_PKG_INVALID_CHECKSUM, ALPM_ERR_PKG_INVALID_SIG, ALPM_ERR_SIG_INVALID, ALPM_ERR_SIG_MISSING