[Bug c++/34124] New: auto_ptr ambiguous conversion

[Bug c++/34124] New: auto_ptr ambiguous conversion

[cfekete1 at gmail dot com]

Hi,

Running the following code:

#include <memory>

using namespace std;

class CBase {};
class CDerived : public CBase {};

void Set(auto_ptr<CBase> base)
{
}

int main(int argc, char *argv[])
{
  auto_ptr<CDerived> derived(new CDerived);

  Set(derived); // error: conversion from 'std::auto_ptr<CDerived>' to
'std::auto_ptr<CBase>' is ambiguous

  auto_ptr<CBase> base(derived); // but this is OK
  base = derived; // this is OK too
}

the Set(derived) gives the mentioned error in the comment. The next two lines
compiles without error so both the copy constructor and the operator= of
auto_ptr works fine. But for some reason the conversion is ambiguous if a
function (in this case Set) is called.

In the next two lines of the compiler output, there are two notes:
/usr/include/c++/4.2.1/memory:368: note: candidates are:
std::auto_ptr<_Tp>::operator std::auto_ptr<_Tp1>() [with _Tp1 = CBase, _Tp =
CDerived]
/usr/include/c++/4.2.1/memory:212: note:
std::auto_ptr<_Tp>::auto_ptr(std::auto_ptr<_Tp1>&) [with _Tp1 = CDerived, _Tp =
CBase]

Please could you check if this is a bug or I made something wrong?

Thanks,
Csaba


-- 
           Summary: auto_ptr ambiguous conversion
           Product: gcc
           Version: 4.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: cfekete1 at gmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34124

[Bug c++/34124] auto_ptr ambiguous conversion

[pcarlini at suse dot de]

------- Comment #1 from pcarlini at suse dot de  2007-11-16 20:26 -------
*** Bug 34125 has been marked as a duplicate of this bug. ***


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34124

[Bug libstdc++/34124] auto_ptr ambiguous conversion

[pcarlini at suse dot de]

------- Comment #2 from pcarlini at suse dot de  2008-01-25 20:31 -------
There isn't much to say: both the templated constructor and the templated
conversion operator must be there per the current C++ standard, and your code
cannot compile. Note that, in general, the design of auto_ptr is considered
seriously broken and therefore it will be deprecated for the next standard and
unique_ptr provided as replacement.


-- 

pcarlini at suse dot de changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34124