Bug#741196: libpetsc3.4.2: libpetsc.so.3.4.2 links with both GPL-licensed and GPL-incompatible libraries

[Francesco Poli (wintermute)]

Package: libpetsc3.4.2
Version: 3.4.2.dfsg1-6
Severity: serious
Justification: Policy 2.3
User: debian-science-maintainers at lists.alioth.debian.org
Usertags: scotch-license-issues

Hello,
the library /usr/lib/libpetsc.so.3.4.2 links with:

  => libumfpack.so.5.6.2, which is under the GNU GPL v2 or later

  => libcholmod.so.2.1.2, which has parts under the GNU GPL v2 or later

  => libptscotch-5.1.so and libptscotcherr-5.1.so, which are released
     under the GPL-incompatible terms of the CeCILL-C v1.0 license

This seems to mean that package libpetsc3.4.2 includes a file which
links with both GPL-licensed and GPL-incompatible libraries.

Please refer to the almost identical bug #740463 for some further
details about the SCOTCH licensing issues.

I think the possible solutions to the issue for petsc are, in
descending order of desirability:

 (A) SCOTCH copyright holders should be contacted and persuaded to
re-license (or dual-license) it under GPLv2-or-later-compatible terms

 (B) SCOTCH should be substituted with a GPLv2-or-later-compatible
replacement, if any is available (METIS seems to be at least
GPLv3-or-later-compatible, see https://bugs.debian.org/740463#15 )

 (C) GPL-licensed library (such as UMFPACK and CHOLMOD) copyright
holders should be asked to relax the copyleft (for instance by switching
to the LGPL v2.1) or add license exceptions that give permission to link
their works with code released under CeCILL-C v1.0


As stated in other bug reports, the best solution is (A). Thus, I renew
my call for help to push in the direction of {re|dual}-licensing SCOTCH
under the GNU LGPL v2.1: please see https://bugs.debian.org/740463#5
for the details.

Thanks for your time!