[Bug 2136855] Re: amd64v3 binary gets stuck in proposed migration (uninst) if binaries are mutually exclusive

[Julian Andres Klode]

On amd64 no libuhd4.9.0 (>= 4.9.0.0+ds1) dependency is emitted; I guess
some symbol shenanigans.

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Title:
  amd64v3 binary gets stuck in proposed migration (uninst) if binaries
  are mutually exclusive

Status in Ubuntu:
  New
Status in apt package in Ubuntu:
  Invalid
Status in uhd package in Ubuntu:
  Triaged

Bug description:
  Hi,
  I reported this on matrix the other day [1] but it seemed not to be recognized right away.
  Therefore it is worth to report this in more detail to allow one to have a look.

  I've came to this via the DPDK transition doing no-change rebuilds of
  its dependencies, but on analyzing found that the current situation in
  resolute-release is the very same.

  It might be more in how apt handles that than proposed-migration,
  hence I'll file against ubuntu itself + apt until we know better. And
  also add a bug tasks with update-excuse tag to hint others at what is
  going on.

  --

  Source: uhd
  Current content in resolute: https://launchpad.net/ubuntu/+source/uhd/4.9.0.0+ds1-1

  In there you will find a binary package that was built twice with
  different options, once with and once without dpdk enabled. Since they
  otherwise do the same they conflict with each other. You have:

  Package: libuhd4.9.0
  and
  Package: libuhd4.9.0-dpdk

  The latter has:
  Provides: libuhd4.9.0
  Conflicts: libuhd4.9.0
  Replaces: libuhd4.9.0

  
  Ok, so far nothing too non-normal.

  But there is a third binary in src:uhd

  Package: libuhd4.9.0-dpdk-tests
  The interesting part here is:
  Depends: libuhd4.9.0-dpdk (= 4.9.0.0+ds1-1), ..., libuhd4.9.0 (>= 4.9.0.0+ds1)


  Now, on all architectures except amd64v3 this is ok.
  One can install libuhd4.9.0-dpdk-tests and AFAICS libuhd4.9.0-dpdk satisfies libuhd4.9.0-dpdk directly and libuhd4.9.0 by the provides.

  But on amd64v3 that pops up in the uninst report [2]

  * amd64v3
  ...
    uhd (4.9.0.0+ds1-1): libuhd4.9.0-dpdk-tests

  
  Setting this up in a resolute container with amd64v3 confirms that.
  (Steps to recreate)

  $ lxc launch ubuntu-daily:r r-amd64v3
  $ lxc shell r-amd64v3
  root at r-amd64v3:~# echo 'APT::Architecture-Variants "amd64v3";' | sudo tee /etc/apt/apt.conf.d/99enable-amd64v3
  root at r-amd64v3:~# sudo apt update
  root at r-amd64v3:~# apt install --dry-run libuhd4.9.0-dpdk-tests

  Solving dependencies... Error!  
  Some packages could not be installed. This may mean that you have
  requested an impossible situation or if you are using the unstable
  distribution that some required packages have not yet been created
  or been moved out of Incoming.
  The following information may help to resolve the situation:

  Unsatisfied dependencies:
   libuhd4.9.0-dpdk-tests : Depends: libuhd4.9.0 (>= 4.9.0.0+ds1)
  Error: Unable to satisfy dependencies. Reached two conflicting decisions:
     1. libuhd4.9.0:amd64=4.9.0.0+ds1-1 is selected for install because:
        1. libuhd4.9.0-dpdk-tests:amd64=4.9.0.0+ds1-1 is selected for install
        2. libuhd4.9.0-dpdk-tests:amd64 Depends libuhd4.9.0 (>= 4.9.0.0+ds1)
     2. libuhd4.9.0:amd64=4.9.0.0+ds1-1 is not selected for install because:
        1. libuhd4.9.0-dpdk-tests:amd64=4.9.0.0+ds1-1 is selected for install as above
        2. libuhd4.9.0-dpdk-tests:amd64 Depends libuhd4.9.0-dpdk (= 4.9.0.0+ds1-1)
        3. libuhd4.9.0-dpdk:amd64 Conflicts libuhd4.9.0

  All three are available on amd64v3 per build [3] and also as seen on
  the system

  root at r-amd64v3:~# apt policy libuhd4.9.0 libuhd4.9.0-dpdk libuhd4.9.0-dpdk-tests
  libuhd4.9.0:
    Installed: (none)
    Candidate: 4.9.0.0+ds1-1
    Version table:
       4.9.0.0+ds1-1 500
          500 http://archive.ubuntu.com/ubuntu resolute/universe amd64v3 Packages
  libuhd4.9.0-dpdk:
    Installed: 4.9.0.0+ds1-1
    Candidate: 4.9.0.0+ds1-1
    Version table:
   *** 4.9.0.0+ds1-1 500
          500 http://archive.ubuntu.com/ubuntu resolute/universe amd64v3 Packages
          100 /var/lib/dpkg/status
  libuhd4.9.0-dpdk-tests:
    Installed: (none)
    Candidate: 4.9.0.0+ds1-1
    Version table:
       4.9.0.0+ds1-1 500
          500 http://archive.ubuntu.com/ubuntu resolute/universe amd64v3 Packages

  Here you see I even installed libuhd4.9.0-dpdk already, which works fine.
  Remember it has: "Provides: libuhd4.9.0" but the install of libuhd4.9.0-dpdk-tests stumbles over that as you can see above.

  
  Could it be that resolving such break/replaces/provides alternative binaries have a problem with sub-arches?

  I feel I'm overlooking something, do not be too angry at me in that case :-/
  Michael said "I don't recognize ... i'll have a think after coffee"
  For me it is not a lack of coffee that makes me suspicious, but a subtle "If it would be what I think it should be more common, so I must miss something".

  
  [1]: https://matrix.to/#/!QMtJBibTYYOCvXJEdv:ubuntu.com/$aiZeg2P-4VA3lP1lYEDB9Oen4tbSZTHEEOMolGZrWIw?via=ubuntu.com&via=matrix.org&via=matrix.debian.social
  [2]: https://ubuntu-archive-team.ubuntu.com/proposed-migration/resolute_uninst.txt
  [3]: https://launchpad.net/ubuntu/+source/uhd/4.9.0.0+ds1-1

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