added 'using namespace' inside generic lambdas to workaround an intel compiler bug

This is related to issue 31 in dune-istl.

Due to an intel compiler bug (it's probably a bug since all other compilers I've tested do not have this issue and it should not be related to compiler flags) a small workaround is necessary in nested functions calls involving generic lambda, see also my stackoverflow question. Especially this occurs in nested Hybrid::forEach calls due to the usage of the subnamespace Hybrid that is not found inside of the lambdas.

The second change removes a warning thrown by intel compilers on unnecessary const on POD return types.

mentioned in commit 99d1dc26

merged

Shouldn't this be backported to 2.6?

Shouldn't this be backported to 2.6?

would be good

changed milestone to %DUNE 2.6.0

In this case, at minimum the milestone should be set to 'DUNE 2.6.0'. Ideally, when merging please create the cherry-pick and assign it to Andreas or myself to make sure we do not overlook it. This holds especially for MRs which are merged after a short period of time, like this one.

mentioned in commit 81795a8c

mentioned in merge request !434 (merged)

mentioned in issue #107