Dear Maintainer,

your package depends on libeigen3-dev. The upstream released a
new major version of this mathematical library, 5.0.0. Some
basic information about new features and changes in this version
can be found here:

https://libeigen.gitlab.io/releases/5.0/

This is a major version change and may require code changes in packages
depending on eigen3. The key breaking changes include:

  - Minimum required C++ standard is now C++14
  - Changes in the build system integration
  - Some API name changes

g2o FTBFS with libeigen3-dev 5.0.1. The full build log is available at:

https://debusine.debian.net/debian/developers-gladk-eigen3/artifact/3755814/

Here is the most probably relevant part of the failing build log:
    ===========================================
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 sbuild-build-depends-main-dummy : Depends: debhelper (>= 11) but it is not going to be installed
                                   Depends: cmake but it is not going to be installed
                                   Depends: libopenblas-dev but it is not going to be installed
                                   Depends: libsuitesparse-dev but it is not going to be installed
                                   Depends: libopengl-dev but it is not going to be installed
                                   Depends: libqglviewer-headers but it is not going to be installed
                                   Depends: libeigen3-dev but it is not going to be installed
                                   Depends: libglut-dev but it is not going to be installed
                                   Depends: libtbb-dev but it is not going to be installed
                                   Depends: libmetis-dev but it is not going to be installed
                                   Depends: libceres-dev but it is not going to be installed
                                   Depends: libgmock-dev but it is not going to be installed
E: Unable to satisfy dependencies. Reached two conflicting assignments:
   1. libceres-dev:amd64 is selected for install because:
      1. sbuild-build-depends-main-dummy:amd64=0.invalid.0 is selected for install
      2. sbuild-build-depends-main-dummy:amd64 Depends libceres-dev
   2. libceres-dev:amd64 Depends libeigen3-dev (< 3.4.1)
      but none of the choices are installable:
      - libeigen3-dev:amd64=3.4.0-5 is not selected for install
apt-get failed.
E: Package installation failed

    ===========================================
libeigen3-dev_5.0.1-1 is available in experimental.

When this package version lands into unstable (probably at the beginning
of June 2026), this bug will be increased in severity to serious.

Thanks,

Anton

Dear maintainers,

eigen3 5.0 (libeigen3-dev 5.0) is now in unstable, so these FTBFS bugs are
release-critical.  I am therefore raising their severity to serious.

Regards,

Anton

We believe that the bug you reported is fixed in the latest version of
g2o, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to 1136234@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Anton Gladky <gladk@debian.org> (supplier of updated g2o package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)
Format: 1.8
Date: Wed, 14 Oct 2026 22:38:15 +0200
Source: g2o
Architecture: source
Version: 0~20230806-6
Distribution: unstable
Urgency: medium
Maintainer: Debian Science Maintainers <debian-science-maintainers@lists.alioth.debian.org>
Changed-By: Anton Gladky <gladk@debian.org>
Closes: 1136234
Changes:
 g2o (0~20230806-6) unstable; urgency=medium
 .
   * Team upload.
   * Fix FTBFS with Eigen 5. (Closes: #1136234)
   * Fix FTBFS with fmt 11.
   * Add debian/libg2o0t64.install to git (it was in the uploaded source
     but missing from the repository) and drop the stale libg2o0.install.
   * Apply cme fix dpkg: debhelper-compat 14, Standards-Version 4.7.4,
     drop debian/compat.
   * Drop manual parallel handling from d/rules, debhelper does it.
   * Add debian/not-installed for upstream tools and CMake files not
     shipped.
   * Add DEP-3 headers to patches.
   * Update debian/copyright, add debian/lrc.config.
   * Switch debian/watch to version 5 GitHub template.
   * Add debian/salsa-ci.yml, build with -j1.
   * Add libspdlog-dev to Depends of libg2o-dev (the installed headers
     include spdlog) and to Build-Depends.
   * Drop redundant Rules-Requires-Root: no.
   * Add debian/upstream/metadata.
   * Add a basic autopkgtest.
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