Re: auto_ptr member gives = no matching function for call to :(

[botik32 <abotezatu at gmail dot com>]

Rodolfo Lima wrote:
> 
> Your problem is that auto_ptr doesn't model the CopyConstructible and 
> Assignable concepts, so you have to manually create the copy constructor 
> and assignment operator and properly deal with auto_ptr semantics
> yourself.
> 

Hello, I have a similar problem as above. Except that when I define a copy
constructor, it does not get called!

Code:
---
#include <stdio.h>
#include <memory>

using namespace std;

class a
{
public:
  int x;
  mutable auto_ptr<int> ptr;

  a( int px=0 )
  { x = px; };

  /*a( const a& )
  {
    printf( "Copy constructor called!\n" );
  };

  a& operator=( const a& )
  {
    printf( "Operator= called!\n" );
  };*/

  ~a() {};
};


inline a funca( void )
{
 a avar;
 return avar;
}

int main( void )
{
  a avar = funca();
  printf( "%d\n", avar.x );
};

---

Compilation error with commented constructor:
---
testinit.cpp: In function 'int main()':
testinit.cpp:30: error: no matching function for call to 'a::a(a)'
testinit.cpp:15: note: candidates are: a::a(a&)
testinit.cpp:12: note:                 a::a(int)
---


After copy constructor and operator= are declared (uncommented):
---
botik@kerrigan ~/devel/temp $ ./a.out 
0
---

I tried it under debug - explicit constructor is not getting called. And the
old pointer in auto_ptr remains and memory gets destroyed leaving me with
random artifacts - if someone gets to use and write to the memory in between
copies, weird things happen.



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