Here's one case that is tricky to get right in c++. At the moment you can call sort(x,y) to sort a range, or sort(x,y,z) to give a comparator. If we allow sort(c) for a container, is sort(c,z) sorting a container with comparator, or a range? It's surprisingly hard to get this right with templates, without concepts.
Do ranges and iterators and comparators even have conflicting requirements? I feel like an object could be all three, in which case it'd be ambiguous what was intended.
No, there's nothing (other than good taste) which stops you from passing a pair of arguments to std::sort() which would be legal for both std::sort(begin, end) and std::sort(range, comparator).
