Merge remote-tracking branch 'origin/develop' into matrix-org-hotfixes

1 files changed, 7 insertions, 0 deletions

diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py

index 2c1b10f652..2a7a6e6982 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -509,6 +509,8 @@ class EventCreationHandler:
                 Should normally be left as None, which will cause them to be calculated
                 based on the room state at the prev_events.
 
+                If non-None, prev_event_ids must also be provided.
+
             require_consent: Whether to check if the requester has
                 consented to the privacy policy.
 
@@ -581,6 +583,9 @@ class EventCreationHandler:
         # Strip down the auth_event_ids to only what we need to auth the event.
         # For example, we don't need extra m.room.member that don't match event.sender
         if auth_event_ids is not None:
+            # If auth events are provided, prev events must be also.
+            assert prev_event_ids is not None
+
             temp_event = await builder.build(
                 prev_event_ids=prev_event_ids,
                 auth_event_ids=auth_event_ids,
@@ -784,6 +789,8 @@ class EventCreationHandler:
                 The event ids to use as the auth_events for the new event.
                 Should normally be left as None, which will cause them to be calculated
                 based on the room state at the prev_events.
+
+                If non-None, prev_event_ids must also be provided.
             ratelimit: Whether to rate limit this send.
             txn_id: The transaction ID.
             ignore_shadow_ban: True if shadow-banned users should be allowed to