Eroare de compilare: main.cpp: In function 'int main()': main.cpp:150:27: error: cannot bind non-const lvalue reference of type 'std::string&' {aka 'std::__cxx11::basic_string<char>&'} to an rvalue of type 'std::string' {aka 'std::__cxx11::basic_string<char>'} 150 | g << sort_set(eval(expr)); | ~~~~^~~~~~ main.cpp:15:23: note: initializing argument 1 of 'std::string sort_set(std::string&)' 15 | sort_set(std::string& str) | ~~~~~~~~~~~~~^~~ Non zero exit status: 1