Bug#926215: dune-pdelab: FTBFS with gcc 8.3

[Ansgar Burchardt]

Control: reassign -1 src:dune-istl 2.6.0-2
Control: affects -1 src:dune-pdelab

Santiago Vila writes:
> /usr/include/dune/istl/paamg/transfer.hh:97:5: error: no declaration matches 'void Dune::Amg::Transfer<V, V1, Dune::Amg::SequentialInformation>::prolongateVector(const Dune::Amg::AggregatesMap<V>&, Dune::Amg::Transfer<V, V1, Dune::Amg::SequentialInformation>::Vector&, Dune::Amg::Transfer<V, V1, Dune::Amg::SequentialInformation>::Vector&, Dune::Amg::Transfer<V, V1, Dune::Amg::SequentialInformation>::Vector&, T, const Dune::Amg::SequentialInformation&, const Redist&)'
>      Transfer<V,V1,SequentialInformation>::prolongateVector(const AggregatesMap<Vertex>& aggregates,
>      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> /usr/include/dune/istl/paamg/transfer.hh:62:19: note: candidates are: 'template<class V, class V1> template<class T1> static void Dune::Amg::Transfer<V, V1, Dune::Amg::SequentialInformation>::prolongateVector(const Dune::Amg::AggregatesMap<V>&, Dune::Amg::Transfer<V, V1, Dune::Amg::SequentialInformation>::Vector&, Dune::Amg::Transfer<V, V1, Dune::Amg::SequentialInformation>::Vector&, T1, const Dune::Amg::SequentialInformation&)'
>        static void prolongateVector(const AggregatesMap<Vertex>& aggregates, Vector& coarse, Vector& fine,
>                    ^~~~~~~~~~~~~~~~
> /usr/include/dune/istl/paamg/transfer.hh:57:19: note:                 'template<class V, class V1> template<class T1> static void Dune::Amg::Transfer<V, V1, Dune::Amg::SequentialInformation>::prolongateVector(const Dune::Amg::AggregatesMap<V>&, Dune::Amg::Transfer<V, V1, Dune::Amg::SequentialInformation>::Vector&, Dune::Amg::Transfer<V, V1, Dune::Amg::SequentialInformation>::Vector&, Dune::Amg::Transfer<V, V1, Dune::Amg::SequentialInformation>::Vector&, T1, const Dune::Amg::SequentialInformation&, const Redist&)'
>        static void prolongateVector(const AggregatesMap<Vertex>& aggregates, Vector& coarse, Vector& fine,
>                    ^~~~~~~~~~~~~~~~
> /usr/include/dune/istl/paamg/transfer.hh:50:11: note: 'class Dune::Amg::Transfer<V, V1, Dune::Amg::SequentialInformation>' defined here
>      class Transfer<V,V1, SequentialInformation>
>            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This is a bug in dune-istl, though I'm not quite sure I understand what
is exactly wrong.  Renaming the template argument from `T` to `T1` in
the definition of `prolongateVector` makes the problem go away, but the
name of template arguments shouldn't really matter?

There is also a template argument `T` in the generic version of the
`Transfer` class...  Maybe that results in the confusion in some way?

Ansgar