LinearAlgebra::EpetraWrappers::Vector has no operator[]()

[marcfehling]

The LinearAlgebra::EpetraWrappers::Vector class has no member function operator[]().

This limits using the class as a template parameter in structures and functions which require that a VectorType needs to be accessed via the bracket operator[].

For example, we cannot explicitly instantiate the SolutionTransfer class with LinearAlgebra::EpetraWrappers::Vector. See also #15706 (comment).

[pcafrica]

This issue has been solved in #16880.

Do we have a list of classes that could not be explicitly instantiated due to this reason and can therefore be adapted?

[bangerth]

I don't think we have such a list. In fact, this is the first time I heard that we have this issue, so it doesn't seem to be too widespread.