Bug#1136245: lbfgspp: FTBFS with libeigen3-dev 5.0 (major version transition)

[Anton Gladky]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512

Package: src:lbfgspp
Version: 0.4.0-1
Severity: important
Tags: sid forky ftbfs
User: debian-devel at lists.debian.org
Usertags: eigen3-5.0

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

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

  https://debusine.debian.net/debian/developers-gladk-eigen3/artifact/3757053/

Here is the most probably relevant part of the failing build log:
    ===========================================
- -- Performing Test WALL_SUPPORTED
- -- Performing Test WALL_SUPPORTED - Success
CMake Error at CMakeLists.txt:41 (find_package):
  Could not find a configuration file for package "Eigen3" that is compatible
  with requested version "3.0".

  The following configuration files were considered but not accepted:

    /usr/share/eigen3/cmake/Eigen3Config.cmake, version: 5.0.1
      The version found is not compatible with the version requested.



- -- Configuring incomplete, errors occurred!
	cd obj-x86_64-linux-gnu && tail -v -n \+0 CMakeCache.txt

    ===========================================
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
-----BEGIN PGP SIGNATURE-----

iQIzBAEBCgAdFiEEu71F6oGKuG/2fnKF0+Fzg8+n/wYFAmoBZ50ACgkQ0+Fzg8+n
/wb61g//T0UQ9UAvu/tQU3HFpyqDvGLujtWXdjMP38i4RRsmqH/Z7L3BqJv9ZL6n
FIk4Q9Vu0vgZoCYugev82Xu2tNlDGC+8gEoM2SOm9rVgPY4NV/pfic45tMfPMiQL
CzBucpGcuDy9xsDGZCKTolUjTWtgjdXg+Mx8WzfWzsfKWYgl15yuio2e7cq1IvPY
YVsFFEpT2CcLAT3UbSQMo1VMk3fnEA5+AJ09vZpAaFdhmZbG8B38b/KiOFDD47iV
wbJxE++nEJgDGbAcGKWdY6p8FnbgJqIrhRH8NSdU+VPAN3/Na5nzczfh2INzmxTF
IzaDQHERxuK4PEM5XJqTDEnmM92N9nh6maBiMkfWEFV78ksPM8MgyDcyXPs/wRzc
cgGnK8F9/LvCRVbJm1BgQOODoQWx6aS/Le6gxF1Y6l3oUjoJCY6wHKFd+G0SG6l8
0h03cY1IA3qqONtrlRaP24GJewwpvzpXWdKmcCXpScLsxd+VQlxNnJj9JI7zA9PM
lxtsAuMtrTeSvbnEU9u3pDCyqfGXjR84IwZKrgcRYbzuubAWhYgfd1cq2VYhzHmS
IXYEFOfJ4hBZrBYwMwS1TYfh001Kt/phmFFEBfYtvVRpb+uzyLyRozuEuYrvR3Ob
6xfGpTpxI8JfzjrFxxtUez7dY+ssjeFidN/d8N6n45UtER+wq80=
=2ave
-----END PGP SIGNATURE-----