c++/3084: anonymous namespace linking

[conversy@emn.fr]

>Number:         3084
>Category:       c++
>Synopsis:       anonymous namespace linking
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          wrong-code
>Submitter-Id:   net
>Arrival-Date:   Fri Jun 08 04:56:02 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:     conversy@emn.fr
>Release:        gcc version 3.0 20010426 (Debian prerelease)
>Organization:
>Environment:
i386-linux
>Description:
anonymous namespace functions cannot be linked
to global call to these functions.

There is an error when linking an object file with
the code of a function declared inside a unnamed
"namespace {}".

In the .o that includes the function code, the name
is the form *__GLOBAL__* where in the .o that refers
to the function code, the name is different.


>How-To-Repeat:
g++ AB.cpp test.cpp

gives: undefined reference to `(anonymous namespace)::operator<<(std::ostream&, (anonymous namespace)::A const&)'


AB.h:

namespace std {
  struct ostream {};
  extern ostream cout;
};

namespace {
  struct A {};
  std::ostream& operator<<(std::ostream&, const A&);
}

namespace foo {
  struct B {};
}

std::ostream& operator<<(std::ostream&, const foo::B&);

AB.cpp:
#include "AB.h"

namespace {
  std::ostream& operator<<(std::ostream& out, const A&) { return out; }
}

std::ostream& operator<<(std::ostream& out, const foo::B&) { return out; }

test.cpp:
#include "AB.h"

main()
{
  A a;
  std::cout << a;
  foo::B b;
  std::cout << b;
}




>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted: