c++ - Lifetime of rvalue reference

Question

I think I have a problem with understanding rvalue references. What is really the lifetime and usage of such construction.

int&& value = 5;

If I understand correctly, 5 is rvalue object (I can't take address of it) and it's temporary - lifetime is end of current expression. Does assigning that to rvalue reference somehow prolong lifetime? If yes, what is the new lifetime of object?

Answer 1

Does assigning that to rvalue reference somehow prolong lifetime?

Yes. Rvalue references can be used to extend the lifetimes of temporary objects (note, lvalue references to const can extend the lifetimes of temporary objects too, but they are not modifiable through them). Thus:

// both will extend the lifetime of the temporary
int&& value = 5;      // modifiable
const int& value = 5; // non-modifiable

If yes, what is the new lifetime of object?

The lifetime of the temporary is extended to match the lifetime of the reference. See lifetime of a temporary.