Steve Langasek:
Hi Niels,
On Thu, Feb 22, 2024 at 07:32:21PM +0100, Niels Thykier wrote:
[...]
I am omitting Breaks, Conflicts, and Replaces because I am not aware of any
users of these at the moment. I am open to adding them, if there is a strong
use-case.
One generic case that this doesn't handle is Essential: yes packages. For
many of these, the ${shlibs:Depends} gets promoted in debian/control to
Pre-Depends, not to Depends.
Maybe it would make sense to auto-aggregate these substvars, *IFF* there is
not already a reference to the substvar in question in the package stanza in
debian/control? This would provide adequate flexibility for any other
exceptions that might be out there, beyond the Pre-Depends case.
Cheers,
In case of a promotion, it does not matter if ${shlibs:Depends} is
applied twice (once in Depends and in Pre-Depends}. You get the
dependencies twice and then dpkg will clean up the duplicates in favor
of the "strongest" dependency[1]. The hard part is a demotion because
this duplication works against you.
Accordingly, the Essential: yes packages that leverage this technique
can just keep doing it without any changes or consequences as far as I
can tell.
Best regards,
Niels
[1] man:dpkg-gencontrol(1):
dpkg-gencontrol reads information from an unpacked Debian source tree
and generates a binary
package control file (which defaults to debian/tmp/DEBIAN/control);
during this process it will
simplify the relation fields.
Thus Pre-Depends, Depends, Recommends and Suggests are simplified in
this order by removing
dependencies which are known to be true according to the stronger
dependencies already parsed.
It will also remove any self-dependency (in fact it will remove any
dependency which evaluates
to true given the current version of the package as installed).
Logically it keeps the
intersection of multiple dependencies on the same package. The order of
dependencies is
preserved as best as possible: if any dependency must be discarded due
to another dependency
appearing further in the field, the superseding dependency will take the
place of the discarded
one.
