C++ Reference Binding

reference_binding.cpp

#include <iostream>
#include <string>

std::string modifiable_rvalue() {
	return "foo";
}

const std::string const_rvalue() {
	return "bar";
}

int main() {
	std::string modifiable_lvalue("baz");
	const std::string const_lvalue("qux");

	std::string& a = modifiable_lvalue;
	//std::string& b = const_lvalue;               // ERROR
	//std::string& c = modifiable_rvalue();        // ERROR
	//std::string& d = const_rvalue();             // ERROR

	const std::string& e = modifiable_lvalue;
	const std::string& f = const_lvalue;
	const std::string& g = modifiable_rvalue();
	const std::string& h = const_rvalue();

	//std::string&& i = modifiable_lvalue;         // ERROR
	//std::string&& j = const_lvalue;              // ERROR
	std::string&& k = modifiable_rvalue();
	//std::string&& l = const_rvalue();            // ERROR

	//const std::string&& m = modifiable_lvalue;   // ERROR
	//const std::string&& n = const_lvalue;        // ERROR
	const std::string&& o = modifiable_rvalue();
	const std::string&& p = const_rvalue();
}