Add ability to set room access based on community membership

[CobaltCause]

Description

Add the ability to set a room's access permissions to "anyone in a user-specified set of related communites". For example, I'd like to be able to let anyone in one or more specific related communities join a room just by knowing it's link, but members from other communities must be invited either directly to the room or to one of the selected communities first.

Version information

• Platform: web
• Browser: Chrome 63
• OS: Arch Linux
• URL: riot.im/app

[lampholder]

Related:

• Should be able to /invite entire communities to rooms #5250
• Room membership synced to group #5241

[dessalines]

I'm surprised this isn't added by default. If I invite a user to my community, and the room is in my community (and it has flair showing that), they still have no access to the room!

[Biep]

We don't want by default to open all rooms to all community members. That would be a way to get into any room: simply create a community with me and the room in it.
And communities can have "subcommunities" with wider access - simple members can only enter some rooms, but board members can enter the boardroom.

[dessalines]

Discord accomplishes this by having groups / roles within a community. You can give someone an invite link, at which point they are "in" a community, but then access is limited by roles / groups which are assignable to community members. This is super helpful since some a role might have permission to several community rooms, and administratie abilities.

[PeterSR]

Any updates on this?

[ptman]

@PeterSR this or a related issue would be updated if there was

[SimonBrandner]

Will be fixed by matrix-org/matrix-spec-proposals#3083

[t3chguy]

This is now possible with Spaces