rvalue method and move assignment shenanigans

main.cpp

#include <iostream>
#include <string>

class Message {
public:
  Message &operator=(const std::string &&msg) && {
    std::cout << msg << std::endl;

    return *this;
  }
};

int main(int argc, char **argv) {
  Message() = std::string("Hello, world!");

  return 0;
}