Bug#1031645: gnome-shell should depend on xdg-desktop-portal-gnome

[Simon McVittie]

On Sun, 19 Feb 2023 at 19:35:37 +0100, Richard B. Kreckel wrote:
> The package should pull in xdg-desktop-portal-gnome.
> 
> After all, "GNOME Shell is the defining technology of the GNOME 3 user
> experience." A system without xdg-desktop-portal-gnome installed will not
> provide some of this experience, like the ability to do screen captures
> (PipeWire) in OBS studio, etc.

I don't think gnome-shell is the right layer to put this dependency.
GNOME Shell is an important component of the complete GNOME user
experience, but it's only a component, and isn't the metapackage
that represents a complete GNOME system in Debian. Depending on how
comprehensive you think "complete" should be, the packages that you
might say "are" GNOME are, in ascending order of size:

* gnome-session, the smallest system that is plausible to refer to as
  being "GNOME", which Depends on gnome-shell and either
  xdg-desktop-portal-gnome or some other backend, and is the package that
  will give you a "GNOME" option in display managers like gdm or lightdm;

* gnome-core, a GNOME system with essential utilities like a login prompt,
  preferences, a file manager and a text editor, which Depends on
  gnome-session, and also on xdg-desktop-portal-gnome specifically;

* gnome, which Depends on gnome-core and adds a relatively complete set
  of desktop applications, and is what you get if you ask for the GNOME
  desktop in the Debian installer (or if you accept Debian's default
  desktop, which is GNOME).

xdg-desktop-portal-gnome also Recommends gnome-shell, so a Depends or
Recommends in the other direction would be circular. Circular Recommends
make it more difficult to remove unneeded packages, so we try to avoid
them.

A system with only gnome-shell and its mandatory dependencies would also
be missing other important parts of the complete GNOME experience, notably
an audio service (pipewire-pulse or pulseaudio) and the Settings app
(gnome-control-center). gnome-core is the layer that is responsible for
pulling these in.

    smcv