C++14: Alternate type deduction on declaration

C++14 added the combined decltype(auto) in order to be able to deduce a reference type. Here is an example:

#include <iostream>
 
int main()
{
  int              lvalue  = 4     ;
  int            & rvalue  = lvalue;
  auto             lvalue2 = rvalue;
  decltype(auto)   rvalue2 = rvalue;
 
  std::cout << (&lvalue == &rvalue ) << " ";
  std::cout << (&lvalue == &rvalue2) << " ";
  std::cout << (&lvalue == &lvalue2) << " ";
  std::cout << std::endl;
 
  return 0;
}
// Output: 1 1 0

Reference: https://en.wikipedia.org/wiki/C%2B%2B14#Alternate_type_deduction_on_declaration.5B5.5D