I was wondering if boost::range or range_v3 will reconciliate free functions and member functions in a similar way that std::begin reconciliates STL containers and C-like arrays (in terms of coding genericity I mean)?
More particularly it would be convenient to me to call std::sort on a list that automatically calls the best possible implementation given by std::list::sort.
At the end, could member functions be seen as interfaces for their generic counterpart only (std::list::sort never called in client code)?
AFAIK, neither library you mention deals with this directly. There is a push to deal with this kind of thing more generally in C++17, including a proposal to make f(x) and x.f() equivalent, but as I mentioned in the comment above, I'm unclear if it will work with range-v3's algorithms.
I did notice an interesting comment in range-v3's sort.hpp: // TODO Forward iterators, like EoP?. So, perhaps Niebler does have ideas to support a more generic sort. ("EoP" is Elements of Programming by Alex Stepanov.)
One complication: A generic sort uses iterators to reorder values, while list::sort() reorders the links themselves. The distinction is important if you care what iterators point to after the sort, so you'd still need a way to select which sort you want. One could even argue that sort() should never call list::sort(), given the different semantics.