Sending a tombstone event in favor of an existing room lead to two annoying side effects

[bmarty]

I observe this by sending a tombstone event to RiotX android room and link the tombstone event to Element-Android room.

It's maybe some sort of a hack usage of tombstone event though.

Steps:

• Send a tombstone event to RoomA including the id of an existing room RoomB

First small bug:

RoomA claims that the room has been upgraded. This is not the case.

First side effect:

Clicking on the link of tombstone event rendering in RoomA send the user to the beginning of RoomB (the create event). In this case, as this is not a room upgrade, user should should land to the latest message of RoomB

Second side effect:

Leaving RoomA makes the app also leaves RoomB which is quite annoying.
RoomB's create event does not refer to RoomA as a predecessor, so in this case RoomB should not be left automatically.

[t3chguy]

2nd side effect is #10380

[t3chguy]

RoomA claims that the room has been upgraded. This is not the case.

Isn't it?

https://matrix.org/docs/spec/client_server/r0.6.1#id160 m.room.tombstone is listed in the Room Upgrades section.

One way of accomplishing this would be hiding the old room from the user's room list and showing banners linking between the old and new room - ensuring that permalinks work when referencing the old room.

[turt2live]

Yea, unfortunately we're not able to tell the difference between a redirect and an upgrade. Abusing tombstones for this purpose is generally not recommended, and the people who did recommend this approach will have known that it'll be counted as an upgrade.

[bmarty]

RoomA claims that the room has been upgraded. This is not the case.

True, sorry, I've seen that on RiotX

[bmarty]

Yea, unfortunately we're not able to tell the difference between a redirect and an upgrade

The m.room.create does not contains a predecessor in case of a redirect.

[turt2live]

The m.room.create does not contains a predecessor in case of a redirect.

From a spec perspective, this is an invalid event not a redirect. Redirects are not a thing.