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From: "zeratul976 at hotmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/56943] New: Incorrect two-phase name lookup for operators
Date: Fri, 12 Apr 2013 23:35:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56943

             Bug #: 56943
           Summary: Incorrect two-phase name lookup for operators
    Classification: Unclassified
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: zeratul976@hotmail.com


When the following code is run:


#include <iostream>

namespace N
{
    struct A
    {
        int operator+(const void*) 
        { 
            return 42; 
        }
    };
}

namespace M
{
    struct B
    {
    };
}


template <typename T, typename U>
int add(T t, U u)
{
    return t + u;
}

int operator+(N::A, M::B*) 
{ 
    return 5; 
}

int main(int argc, char** argv)
{
    N::A a;
    M::B b;
    std::cout << add(a, &b) << "\n";
}


the output is "5". I believe the correct output wouldbe "42", because when
looking up operator+ in the expression "t + u", the operator+(N::A, M::B*)
overload is found neither by unqualified lookup at the point of definition
(since it is not declared yet at the point of definition), nor by
argument-dependent lookup at the point of instantiation (since it is not in the
namespace of either of its arguments).

Clang outputs "42" for this example, as expected.