[draft] Allow equality comparison of TransformedRangeIterator classes with same base iterator

So far comparision was only provided for identical TransformedRangeIterator type. This is generalized to allow equality/inequlity comparison of different types as long as the base iterator is the same. This is reasonable, since comparisons anyway rely on the base type only. The patch is needed if we want to allow to generate TransformedRangeIterators only with lambdas, since each lambda has a different type.

The latter functionality is tested and demonstrated in the respective test. We may later want to provide a public factory method for creating such iterators (which should probably stay in Dune::Impl:: themselves).

marked this merge request as draft

mentioned in merge request !1386

added 1 commit

• 30863d30 - Allow equality comparison of TransformedRangeIterator classes with same base iterator

Compare with previous version

Somehow clang-11 sees an ambiguity if templated operator== and operator!= are both defined in the base class. People noticed similar issues elsewhere and fixed it by importing the operators in the derived class. I don't fully understand the problem, but this patch does not harm.

Seems to work.

Maybe the issue is related to the defaulted comparison operators in c++20: https://en.cppreference.com/w/cpp/language/default_comparisons

This was superseded by !1396 (merged) which provides this comparison as a byproduct.

closed