Method func3

tests/test_methods_and_attributes.cpp:299–299

    std::size_t func1(std::string &&s) { return s.size(); }
    std::size_t func2(std::string &&s) const { return s.size(); }
    std::size_t func3(std::string &&s) & { return s.size(); }
    std::size_t func4(std::string &&s) const & { return s.size(); }
};