If you used a debian/librm0.symbols file you could easily see the ABI break. Here's the diff generated by the build with a symbols file. The + lines are fine as they are new symbols. The - lines mean that a symbol was removed.
The original bug report pointed out that roger-router no longer builds from source because there is an undefined reference to "rm_router_load_journal" . That is one of the removed symbols. --- debian/librm0.symbols (librm0_2.2.2-1_amd64) +++ dpkg-gensymbolsjYHes7 2021-10-01 23:21:43.628233777 +0000 @@ -211,6 +211,7 @@ rm_audio_write@Base 2.1.4 rm_call_by_call_prefix_length@Base 2.1.4 rm_call_by_call_table@Base 2.1.4 + rm_call_entry_dup@Base 2.2.2-1 rm_call_entry_free@Base 2.1.4 rm_call_entry_new@Base 2.1.4 rm_connection_add@Base 2.1.4 @@ -248,6 +249,7 @@ rm_fax_hangup@Base 2.1.4 rm_fax_register@Base 2.1.4 rm_fax_send@Base 2.1.4 + rm_faxserver_emit_fax_process@Base 2.2.2-1 rm_faxserver_init@Base 2.1.4 rm_faxserver_thread@Base 2.1.4 rm_file_load@Base 2.1.4 @@ -285,6 +287,8 @@ rm_init@Base 2.1.4 rm_init_directory_paths@Base 2.1.4 rm_journal_add_call_entry@Base 2.1.4 + rm_journal_dup@Base 2.2.2-1 + rm_journal_free@Base 2.2.2-1 rm_journal_load@Base 2.1.4 rm_journal_save@Base 2.1.4 rm_journal_save_as@Base 2.1.4 @@ -339,7 +343,7 @@ rm_object_emit_contact_process@Base 2.1.4 rm_object_emit_contacts_changed@Base 2.1.4 rm_object_emit_fax_process@Base 2.1.4 - rm_object_emit_journal_loaded@Base 2.1.4 +#MISSING: 2.2.2-1# rm_object_emit_journal_loaded@Base 2.1.4 rm_object_emit_message@Base 2.1.4 rm_object_emit_profile_changed@Base 2.1.4 rm_object_get_type@Base 2.1.4 @@ -430,8 +434,12 @@ rm_router_is_locked@Base 2.1.4 rm_router_load_fax@Base 2.1.4 rm_router_load_fax_reports@Base 2.1.4 - rm_router_load_journal@Base 2.1.4 +#MISSING: 2.2.2-1# rm_router_load_journal@Base 2.1.4 + rm_router_load_journal_async@Base 2.2.2-1 + rm_router_load_journal_finish@Base 2.2.2-1 rm_router_load_voice@Base 2.1.4 + rm_router_load_voice_mail_async@Base 2.2.2-1 + rm_router_load_voice_mail_finish@Base 2.2.2-1 rm_router_load_voice_records@Base 2.1.4 rm_router_login@Base 2.1.4 rm_router_logout@Base 2.1.4 Thanks, Jeremy Bicha
