c++ - Returning temporary, why not a rvalue reference? -

a rvalue reference temporary object right? why isn't following compiling? thought function returned rvalue reference

main.cpp:40:12: error: no viable conversion 'hello3 ()' 'hello4'     hello4 lol = returning; 

in code

#include <iostream> #include <string> #include <vector>  class hello {   public:   };   class hello2 {   public:   };  class hello3 {   public:     hello obj1;   hello2 obj2;  };   class hello4 {  public:   hello4(hello3&&) {   std::cout << "he";     }  };  hello3 returning() {     hello a;     hello2 b;     return {a,b};  }  int main() {     hello4 lol = returning; } 

i read move semantics documents still don't understand why above doesn't bind rvalue reference

a rvalue reference temporary object right?

no, it's reference object might or might not temporary.

why isn't following compiling?

because left (empty) argument list off function call:

hello4 lol = returning();                       ^^ 

the error message indicates code tries assign function, not result of calling function, variable.

i thought function returned rvalue reference

no, returns object, since there's nothing reference refer to. temporary object can bind rvalue reference, can used construct hello4.