I thought references must not be used in std containers, at least not without std::reference_wrapper.
So std::tuple<const query&> is just not correct, right?
A `std::tuple` is not a container in the STL sense (it also doesn't provide iterators and you can't add or delete elements from it), so there is no issue in that regard. For example, `std::tie()` is a function in the standard library that returns a tuple of references.