>
> I think istringstream should have an optimised method to assimilate an
> Rvalue string:
>
> We have such constructor already -
https://en.cppreference.com/w/cpp/io/basic_istringstream/basic_istringstream
(6)

This code compiles and the program returns 1.

#include <string>
#include <sstream>

int main()
{
    std::string str = "this is a very long string";
    std::istringstream sstream(std::move(str));
    return str.empty();
}