From 6b770d8bfc8bbc27aa7681436aa47fb41cb7911e Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Thu, 5 Sep 2024 15:43:37 +0100
Subject: [PATCH] Revert "Fix bump stamp for non-joined rooms"

This reverts commit f73c844403de00630fd773075cefe6f502b54e69.
---
 synapse/handlers/sliding_sync/__init__.py     | 40 ++++++++---------
 .../client/sliding_sync/test_rooms_meta.py    | 45 -------------------
 2 files changed, 19 insertions(+), 66 deletions(-)

diff --git a/synapse/handlers/sliding_sync/__init__.py b/synapse/handlers/sliding_sync/__init__.py
index f76b846fcc7..ac6dc79fdf0 100644
--- a/synapse/handlers/sliding_sync/__init__.py
+++ b/synapse/handlers/sliding_sync/__init__.py
@@ -967,29 +967,27 @@ async def get_room_sync_data(
                     )
                 )
 
-        # By default, just choose the membership event position
-        bump_stamp = room_membership_for_user_at_to_token.event_pos.stream
-
-        # Figure out the last bump event in the room if we're in the room.
-        if room_membership_for_user_at_to_token.membership == Membership.JOIN:
-            last_bump_event_result = (
-                await self.store.get_last_event_pos_in_room_before_stream_ordering(
-                    room_id,
-                    to_token.room_key,
-                    event_types=SLIDING_SYNC_DEFAULT_BUMP_EVENT_TYPES,
-                )
+        # Figure out the last bump event in the room
+        last_bump_event_result = (
+            await self.store.get_last_event_pos_in_room_before_stream_ordering(
+                room_id,
+                to_token.room_key,
+                event_types=SLIDING_SYNC_DEFAULT_BUMP_EVENT_TYPES,
             )
+        )
 
-            # But if we found a bump event, use that instead
-            if last_bump_event_result is not None:
-                _, new_bump_event_pos = last_bump_event_result
-
-                # If we've just joined a remote room, then the last bump event may
-                # have been backfilled (and so have a negative stream ordering).
-                # These negative stream orderings can't sensibly be compared, so
-                # instead we use the membership event position.
-                if new_bump_event_pos.stream > 0:
-                    bump_stamp = new_bump_event_pos.stream
+        # By default, just choose the membership event position
+        bump_stamp = room_membership_for_user_at_to_token.event_pos.stream
+        # But if we found a bump event, use that instead
+        if last_bump_event_result is not None:
+            _, new_bump_event_pos = last_bump_event_result
+
+            # If we've just joined a remote room, then the last bump event may
+            # have been backfilled (and so have a negative stream ordering).
+            # These negative stream orderings can't sensibly be compared, so
+            # instead we use the membership event position.
+            if new_bump_event_pos.stream > 0:
+                bump_stamp = new_bump_event_pos.stream
 
         unstable_expanded_timeline = False
         prev_room_sync_config = previous_connection_state.room_configs.get(room_id)
diff --git a/tests/rest/client/sliding_sync/test_rooms_meta.py b/tests/rest/client/sliding_sync/test_rooms_meta.py
index fe44aa7abd8..4ed49040c16 100644
--- a/tests/rest/client/sliding_sync/test_rooms_meta.py
+++ b/tests/rest/client/sliding_sync/test_rooms_meta.py
@@ -758,48 +758,3 @@ def test_rooms_bump_stamp_backfill(self) -> None:
         response_body, _ = self.do_sync(sync_body, tok=user1_tok)
 
         self.assertGreater(response_body["rooms"][room_id]["bump_stamp"], 0)
-
-    def test_rooms_bump_stamp_invites(self) -> None:
-        """
-        Test that `bump_stamp` is present and points to the membership event,
-        and not later events, for non-joined rooms
-        """
-
-        user1_id = self.register_user("user1", "pass")
-        user1_tok = self.login(user1_id, "pass")
-
-        user2_id = self.register_user("user2", "pass")
-        user2_tok = self.login(user2_id, "pass")
-
-        room_id = self.helper.create_room_as(
-            user2_id,
-            tok=user2_tok,
-        )
-
-        # Invite user1 to the room
-        invite_response = self.helper.invite(room_id, user2_id, user1_id, tok=user2_tok)
-
-        # More messages happen after the invite
-        self.helper.send(room_id, "message in room1", tok=user2_tok)
-
-        # We expect the bump_stamp to match the invite.
-        invite_pos = self.get_success(
-            self.store.get_position_for_event(invite_response["event_id"])
-        )
-
-        # Doing an SS request should return a `bump_stamp` of the invite event,
-        # rather than the message that was sent after.
-        sync_body = {
-            "lists": {
-                "foo-list": {
-                    "ranges": [[0, 1]],
-                    "required_state": [],
-                    "timeline_limit": 5,
-                }
-            }
-        }
-        response_body, _ = self.do_sync(sync_body, tok=user1_tok)
-
-        self.assertEqual(
-            response_body["rooms"][room_id]["bump_stamp"], invite_pos.stream
-        )