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

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

https://debusine.debian.net/debian/developers-gladk-eigen3/artifact/3761837/

Here is the most probably relevant part of the failing build log:
    ===========================================

Hi,

The attached patches fix this bug, I will upload a new version with them
as soon as Eigen 5.x reaches unstable.

Best wishes,

Also with this third one, attached, sorry.

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
spectra, 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 1136332@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Pierre Gruet <pgt@debian.org> (supplier of updated spectra 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: Fri, 04 Sep 2026 08:49:55 +0200
Source: spectra
Architecture: source
Version: 1.2.0-2
Distribution: unstable
Urgency: medium
Maintainer: Debian Math Team <team+math@tracker.debian.org>
Changed-By: Pierre Gruet <pgt@debian.org>
Closes: 1136332
Changes:
 spectra (1.2.0-2) unstable; urgency=medium
 .
   * Explicitly looking for the Debian library installed in Debian
   * Building against Eigen 5.0.1: acknowledging interface changes and
     having more iterations in one test (Closes: #1136332)
   * B-D on debhelper-compat 14, removing misc: and shlibs: substvars
   * Raising Standards version to 4.7.4:
     - Removing Priority: optional, which is now defaults
     - Removing R-R-R:no, which is now defaults
   * Raising d/watch version to 5
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 70886f71451206163e45dae8c9349a37efc3ccb6 5436 spectra_1.2.0-2.debian.tar.xz
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