error: no matching function for call to `Anton::Anton(Anton)`

[e.karge]

> Eljay Love-Jensen wrote:
>> Hi Eric,
>>
>> You should put a copy constructor in your Anton class.
>>
>> "Anton(Anton& a)" isn't a copy constructor.  You need an "Anton(Anton
>> const& a)".
> Anton (Anton &), _is_ a copy constructor, it just isn't a const copy
> constructor.
> [12/1]/10
>
> You'll be able to copy non-const objects, but not copy const ones.

Sorry... maybe the example was somewhat too simple. An example, which is
closer to what I need is the following (in "reality", f() is the
constructor of another class, but the one below does not work either):

class A
{
public:
    A( const A& ){}
    A( A& ){}
    A( int ){}
    A& ref(){return *this;}
};

int f( A& ){ return 3; }

int main (int, char **)
{
  return f( A( 3 ) );       // error: could not convert `A(3)' to `A&'
  return f( A( 3 ).ref() ); // works
}

i wonder why it is not possible to convert to A& outside of the temporary
object but inside.

regards,
Eric.