Can you justify this patch a bit? I'm still not convinced that applications should survive this change trivially. And if they should, it sounds more like an upstream issue. :)

I'm not certain either, so I opened rblaze/haskell-dbus#37 :)
Anyway, they have basically getenv "DBUS_SESSION_BUS_ADDRESS" >>= parseAddress, and at the same time they bundle a parseAddresses (which this patch uses) which is for some reason used nowhere internally.
So if that address format is legal, it should be properly supported (and probably not like in this patch, but by trying each of them in sequence on failure).

I can't log into none + xmonad at all after update to latest nixos-unstable and reboot. I'm using dbus in my xmonad config as well. Is this the same issue?

That is likely. You could start an xterm or i3 session and run it manually, then you should see some related error message. Or apply the patch locally and don't forget xmonad --recompile.

so far I tried to use gnome + xorg and tried to run xmonad from terminal there. I can confirm I see error related to dbus. When I rollback to the generation where xmonad works for me and try to run it under gnome I don't see this error but expected BadAccess one so I think this is indeed the cause.

Now I can fully confirm that this turboMaCk/Dotfiles#19 resolved all issues for me.

This sounds like an issue that upstream should make a decision about -- not we.

Looks like they will, or they would also accept this patch, see linked issue above.
Meanwhile we should still merge this until an upgrade is in place (since the multiple addresses are probably here to stay?).

Looks like they will, or they would also accept this patch, see linked issue above.

Once they have accepted this patch, I'll be perfectly happy to apply it to our package, too.

Once they have accepted this patch, I'll be perfectly happy to apply it to our package, too.

I've submitted a PR on that repo based on the post patch of @averelld . If that is accepted when can either use that version of dbus or ship the patch on nixos and apply it locally.

The PR was accepted and merged, haskell-dbus v1.2.11 was published. We should use that.

We have dbus-1.2.11 in haskell-updates already. It's not used by default yet, because LTS Haskell still recommends the 1.2.7 version. I suppose that would change with the next release.

Closing, this will be solved by an upstream update with this change instead.