[Bug c++/24011] New: ambiguous overload reported for no obvious reason

[Bug c++/24011] New: ambiguous overload reported for no obvious reason

[andre_orwell at yahoo dot com dot au]

// Barebones code to reproduce the problem: 
// Interface 
namespace NS 
{ 
    template<typename T> class X {}; 
 
    template<typename T> X<T> operator*(const X<T> &a, const X<T> &b); 
} 
 
// Implementation 
template<typename T> 
NS::X<T>operator*(const NS::X<T> &a,const NS::X<T> &b) 
{ 
    return NS::X<T>(); 
} 
 
// Application 
int main(int argc, char *argv[]) 
{ 
    NS::X<int> tmp = NS::X<int>() * NS::X<int>(); 
} 
 
 
 
What I get: 
 
-bash-3.00$ uname -a 
Linux elisha.research.canon.com.au 2.6.12-1.1447_FC4smp #1 SMP Fri Aug 26 
20:57:13 EDT 2005 i686 i686 i386 GNU/Linux 
-bash-3.00$ gcc --version 
gcc (GCC) 4.0.1 20050727 (Red Hat 4.0.1-5) 
Copyright (C) 2005 Free Software Foundation, Inc. 
This is free software; see the source for copying conditions.  There is NO 
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 
 
 
-bash-3.00$ make strange 
g++ -g    strange.cpp   -o strange 
strange.cpp: In function 'int main(int, char**)': 
strange.cpp:19: error: ambiguous overload for 'operator*' in 'NS::X<int>() * 
NS::X<int>()' 
strange.cpp:11: note: candidates are: NS::X<T> operator*(const NS::X<T>&, 
constNS::X<T>&) [with T = int] 
strange.cpp:6: note:                 NS::X<T> NS::operator*(const NS::X<T>&, 
const NS::X<T>&) [with T = int] 
make: *** [strange] Error 1 
 
 
If I place the implementation within the scope of the namespace geometry{...} 
then it seems to compile fine.  However the above does not appear to cause 
problems using MSVC.  Problem exists with gcc 3.3.2 and 3.3.4.  Is this code 
incorrect??? 
 
Thanks

-- 
           Summary: ambiguous overload reported for no obvious reason
           Product: gcc
           Version: 4.0.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: andre_orwell at yahoo dot com dot au
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: redhat.x86.linux
  GCC host triplet: redhat.x86.linux
GCC target triplet: redhat.x86.linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24011

[Bug c++/24011] ambiguous overload reported for no obvious reason

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-09-22 15:17 -------
the error message about ambiguous overload is correct as there are two functions there.
operator* in the global namespace and operator* in the NS namespace.
You most likely wanted to implement operator* in the NS namespace and not a new one in the global 
namespace.

The following code does what you wanted to do:
// Barebones code to reproduce the problem: 
// Interface 
namespace NS
{
    template<typename T> class X {};

    template<typename T> X<T> operator*(const X<T> &a, const X<T> &b);
}

// Implementation 
template<typename T>
NS::X<T>NS::operator*(const NS::X<T> &a,const NS::X<T> &b)
{
    return NS::X<T>();
}

// Application 
int main(int argc, char *argv[])
{
    NS::X<int> tmp = NS::X<int>() * NS::X<int>();
}

Notice how I wrote the Implementation.

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24011

[Bug c++/24011] ambiguous overload reported for no obvious reason

[andre_orwell at yahoo dot com dot au]

------- Additional Comments From andre_orwell at yahoo dot com dot au  2005-09-23 13:34 -------
Subject: Re:  ambiguous overload reported for no obvious reason

Thanks - obvious when its pointed out.  Sorry for the bother.

On Friday 23 September 2005 01:17, pinskia at gcc dot gnu dot org wrote:
> The following code does what you wanted to do:
...
> Notice how I wrote the Implementation.



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24011