When does it matter that `this` is an rvalue?

Question

I know that the type of this is a prvalue ("pure" rvalue) pointer, and that it may be made a pointer-to-const and/or pointer-to-volatile (affecting accesses to its instance variables), by appending the keywords const or volatile to the end of the function definition to which it belongs.

I also know that this is sometimes (incorrectly) described as being a const pointer, perhaps as a way of saying "you can't make an assignment to this". As an rvalue, it is inherently unassignable, and so there is no need for the concept of a const rvalue.

I also know that in C++11, there are cases where being an rvalue or an lvalue can affect call resolution, but I've tried to work through the possibilities, and I'm not sure whether there's a case where it would actually matter to call resolution that this is an rvalue pointer rather than a const lvalue pointer.

Is there a case where this distinction makes a real difference, from a programmer's perspective, such as a context where an rvalue pointer can be used that a const lvalue pointer cannot be used, where a const lvalue pointer can be used that an rvalue pointer cannot, or where the difference affects call resolution?

Answer 1

An obvious consequence of this being an prvalue is that &this is illegal. So, built-in unary operator & makes an example of "where a const lvalue pointer can be used that an rvalue pointer cannot". For the very same fundamental reason direct binding of references to this is not possible.

Also, prvalue-ness of this means that this itself cannot be const or volatile, since scalar rvalues cannot have cv-qualified types.

It is probably hard to build non-esoteric real-life code examples based on these distinctions.