Bug#985914: xdg-desktop-portal-kde: should be Multi-Arch: foreign, so it satisfies steam:i386 Recommends

[Simon McVittie]

Control: retitle -1 xdg-desktop-portal-kde: should be Multi-Arch: foreign, so it satisfies steam:i386 Recommends
Control: reassign -1 xdg-desktop-portal-kde
Control: affects -1 + steam
Control: tags -1 + patch

On Thu, 25 Mar 2021 at 17:49:42 -0500, Boyd Stephen Smith Jr. wrote:
> steam:i386 has a recommendation for xdg-desktop-portal-backend:i386
...
> xdg-desktop-portal-kde fails to satisfy the dependency.
> 
> xdg-dekstop-portal-kde:i385 conflicts (via libkf5services-bin) with my 64-bit
> KDE Plasma environemtn.
..
> Maybe this is not properly a steam bug, and should be handled by
> xdg-dekstop-portal-kde source package instead.

Yes, I think this is something for xdg-desktop-portal-kde to
solve. It should almost certainly be Multi-Arch: foreign, like
xdg-desktop-portal-gtk is, so that xdg-desktop-portal-kde:amd64
can simultaneously satisfy the dependencies of (for example) both
flatpak:amd64 and steam:i386.

xdg-desktop-portal users like Flatpak and Steam communicate with the
portal (and, indirectly, its backends) via an architecture-independent
D-Bus interface, so it doesn't matter if their architectures don't
match. This is exactly the use-case for which Multi-Arch: foreign was
designed.

Untested patch:
https://salsa.debian.org/qt-kde-team/kde/xdg-desktop-portal-kde/-/merge_requests/7

> But, I do think stream
> architecture-dependent dependency is a big part of why this isn't working so
> well for me.

Sorry, there is no change to steam that can solve this. As long
as xdg-desktop-portal-kde is Multi-Arch: no (the default), the dpkg
dependency system does not provide a way for steam to declare a dependency
on "xdg-desktop-portal-kde of any architecture".

Workaround: install xdg-desktop-portal:amd64 and
xdg-desktop-portal-kde:amd64, and either leave steam's Recommends on
xdg-desktop-portal-backend unsatisfied, or install xdg-desktop-portal-gtk
as well (any architecture, but preferably amd64).

In a KDE/Plasma environment, xdg-desktop-portal should still prefer to use
xdg-desktop-portal-kde (as a result of the XDG_CURRENT_DESKTOP environment
variable) even if xdg-desktop-portal-gtk is also installed, so you should
still get KDE-style UIs rather than GTK/GNOME-style UIs while running a
KDE/Plasma session.

    smcv