Wolfgang Bangerth

Nothing to see here, just opening the PR so I can share with @jppelteret.

Mark potentially-unused variables with [[maybe_unused]] instead of saying (void)x;

3

C++ has a way of saying "ignore this value", namely ``` std::ignore = x; ``` What we use currently is the C-style idiom ``` (void)x; ``` Neither are entirely obvious...

Have a function FiniteElement::shape_function_belongs_to(i, ...extractor...).

1

In writing step-91 (see #17419), I once again had to face the ugliness of writing ``` if (fe.system_to_component_index(i).first.first == ...) ``` or some such, which really isn't helpful or obvious....

Serialization of sequential Triangulation should also serialize cell-attached data.

2

In writing step-83 (#12429), it turns out to be annoying that `Triangulation::save(archive)` does not do the same as `Triangulation::save(filename)`. The former writes everything about the triangulation's own cells into the...

Parallel serialization tutorial.

3

step-83 (see #12429) only shows how to serialize a sequential program. That is undesirable, but expedient for getting the program merged in time for the current release. Here are some...