[Bug c++/55038] New: c++11: operator +=

["lisp2d at lisp2d dot net" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55038

             Bug #: 55038
           Summary: c++11: operator +=
    Classification: Unclassified
           Product: gcc
           Version: 4.7.1
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: lisp2d@lisp2d.net


I transfer code to c++(2011) version and hear: the main goal is to advance
using an rvalue.
 But standard say that operators +=,++,-=,-- must have an lvalue from the left
side.
 Who are writes the standard? 
 And why I must to write cover class?
 And I want to hear an advice.

code:

#include  <iostream>
#include  <complex>

namespace test{

class Int{
public:
  signed  int i;
  Int()noexcept:i(){}
  constexpr Int(Int const & x)noexcept:i{x.i}{}
  constexpr explicit  Int(signed  int const & x)noexcept:i{x}{}
  Int & operator  =(Int const & x)noexcept{i  = (x.i);return  * this;}
  void  Swap(Int  &  x){std::swap(i,x.i);}
  Int operator  +(Int  const & x){return  Int{i + (x.i)};}
  Int & operator  +=(Int  const & x){i  +=  (x.i);return  * this;}
};

int main(int,char * *){
  Int x{1};
  Int y{2};
  Int z{3};
  std::cout <<  "(" <<  x.i <<  "+" <<  y.i <<  ")+=" <<  z.i <<  " = " <<  ((x
+ y) +=  z).i <<  std::endl;
  std::complex<int>  cx{1};
  std::complex<int>  cy{2};
  std::complex<int>  cz{3};
  std::cout <<  "(" <<  cx <<  "+" <<  cy <<  ")+=" <<  cz <<  " = " <<  ((cx +
cy) +=  cz) <<  std::endl;
  int ix{1};
  int iy{2};
  int iz{3};
  //std::cout <<  "(" <<  ix <<  "+" <<  iy <<  ")+=" <<  iz <<  " = " <<  ((ix
+ iy) +=  iz) <<  std::endl;
  }

} // namespace test

int main(int  n,char * *  a){
  return  test::main(n,a);}