On Fri, Jan 08, 2016 at 12:22:50PM +0200, Niko Tyni wrote: > On Wed, Jan 06, 2016 at 11:06:35PM -0700, Adam Conrad wrote: > > > 1) The "hint" for complete replacement of A with B for high level > > dpkg frontends is an unversioned Conflicts/Replaces pair. > > 2) Virtual packages are defined as a Provides, or Provides/Conflicts > > if they shouldn't be installed together, or Provides/Conflicts > > and Replaces if they have file overlaps. > > is very helpful. > > The general impression I have is that as Conflicts imposes much > stronger constraints on upgrade ordering, it should be used sparingly. > To that end, I'm wondering if we should have perl-modules-5.22 > Breaks: perl-modules (<< 5.22.0~) > Provides: perl-modules > but leave the Replaces out, effectively dropping the (currently broken) > "hint" for complete replacement and letting the dpkg frontends to figure > that out themselves. Do you have an opinion about that?
The only hint that frontends are guaranteed to understand for swapping packages is Conflicts/Replaces, apt itself will suggest removal of packages to try to reach your upgrade goal, but more cautious frontends like unattended-upgrades or update-manager will only allow removals in that one specific case, to avoid unintentional removals. > I see you've filed this at severity:important. While I'm not disputing > that, is there some specific trouble this is causing? I filed it as important because it stalls upgrades with the above- mentioned "cautious" frontends and forces user intervention with apt or dselect/aptitude to get the desired result. Given the above, I think the only reasonable solution right now is to move your Breaks to a Conflicts. As a side note, you may also want to make your Provides versioned, as having it unversioned has suddenly swapped meaning for dependencies such as: Depends: perl-modules (>= 5.10) | libcgi-pm-perl (>= 3.35) An unversioned Provides is evaluated as version 0:0.0, which means an upgrade that's removing perl-modules will pull in libcgi-pm-perl, even though that shouldn't be necessary. A versioned Provides would fix that. ... Adam
