[Pkg-utopia-maintainers] Bug#1072756: dbus: should depend on recent base-files, and only versioned on usr-is-merged as fallback

[Helmut Grohne]

Hi Jonas,

On Fri, Jun 07, 2024 at 05:00:44PM +0200, Jonas Smedegaard wrote:
> dbus depends versioned on usr-is-merged, which is now a transitional
> package depending on base-files.
> 
> Please change the dependency to be declared like this:
> 
>   Depends: base-files (>= 13.3~) | usr-is-merged (>= 38~)
> 
> That allows dropping the transitional package.

I think this request is not reasonable as is. Let's find out what we
really want here.

The semantics of base-files (>= 13.3~) and usr-is-merged (>= 38~)
actually differ and your proposed change weakens the promises. In
particular, usr-is-merged declares Conflicts for a fair number of
packages to ensure that certain bugs are not present. base-files does
not carry these conflicts, so by adding the alternative you are implying
that these conflicts would be no longer needed.

Then when you do not need the Conflicts, you might as well change the
dependency to unversioned usr-is-merged as the only important features
(from a client package pov) that usr-is-merged gained with higher
versions are those Conflicts. Once you weaken it to the unversioned
usr-is-merged, the provides from base-files actually suffices. It does
seem reasonable that someone added the version restriction by accident.
For dbus, it was added via #1054650, but the bug log does not express
why the version restriction was needed.

It would also be conceivable to have base-files do versioned provides of
usr-is-merged. I considered this and concluded that it was a bad idea,
because base-files would have to also carry all those Conflicts then. We
want base-files to be upgraded early and those Conflicts would cause it
to get upgraded late even though they are only really needed in some
cases such as dbus. Hence I intentionally opted for not copying the
Conflicts and thus not doing versioned provides.

Given the above, it feels right to me that dbus pulls the physical
usr-is-merged package whose purpose at this time is forcing other
packages off the system.

In the event that the Conflicts are not important to dbus, the obvious
solution is to drop the version. In this case, waiting for base-files to
migrate is not required. In no case is adding a base-files alternative a
good thing to do.

Helmut