FTBFS with cgal 5.6

[Andreas Hasenack]

In file included from /home/ubuntu/deb/mshr/mshr-2019.2.0~git20200924.c27eb18+dfsg1/src/CSGCGALMeshGenerator3D.cpp:43:
/home/ubuntu/deb/mshr/mshr-2019.2.0~git20200924.c27eb18+dfsg1/src/make_multicomponent_mesh_3.h: In function ‘void make_multicomponent_mesh_3_impl(C3T3&, const MeshDomain&, const MeshCriteria&, const CGAL::parameters::internal::Exude_options&, const CGAL::parameters::internal::Perturb_options&, const CGAL::parameters::internal::Odt_options&, const CGAL::parameters::internal::Lloyd_options&, bool, const CGAL::parameters::internal::Mesh_3_options&)’:
/home/ubuntu/deb/mshr/mshr-2019.2.0~git20200924.c27eb18+dfsg1/src/make_multicomponent_mesh_3.h:44:29: error: ‘has_Has_features’ is not a member of ‘CGAL::Mesh_3::internal’; did you mean ‘CGAL::internal::has_Has_features’?
   44 | CGAL::Mesh_3::internal::has_Has_features<MeshDomain>::value > () (c3t3,
      | ^~~~~~~~~~~~~~~~

[Andreas Hasenack (ahasenack)]

Note mshr might be abandoned[1] upstream[2].

Last commit[3] is from September 2020.

1. https://fenicsproject.discourse.group/t/building-from-source-mshr-branch-not-availlable/7565/3
2. https://bitbucket.org/fenics-project/mshr/src/master/
3. https://bitbucket.org/fenics-project/mshr/commits/

[Andreas Hasenack (ahasenack)]

We may be able to remove mshr and disable mshr support which seems to be considered deprecated anyway. It's pulled-in via the fenics metapackage, which says:

 This is the legacy version of FEniCS. You may want to consider
 installing the next-generation FEniCS-X (fenicx package).

The fenicsx metapackage does not pull mshr in:

 FEniCS-X is the next-generation implementation of FEniCS
 (with DOLFIN-X, FFC-X)

That being said, I don't know this ecosystem, and couldn't tell the impact this decision (dropping mshr) would have.

[Andreas Hasenack (ahasenack)]

Fixed in https://launchpad.net/ubuntu/+source/mshr/2019.2.0~git20200924.c27eb18+dfsg1-10