What's a use case for overloading member functions on reference qualifiers?

Question

C++11 makes it possible to overload member functions based on reference qualifiers:

class Foo {
public:
  void f() &;   // for when *this is an lvalue
           


        

Answer 1

If f() needs a Foo temp that is a copy of this and modified, you can modify the temp this instead while you can't otherwise