[Bug c++/13420] New: #pragma interface/implementation lead to link problems on Cygwin

["arnaud dot desitter at ouce dot ox dot ac dot uk" <gcc-bugzilla at gcc dot gnu dot org>]

On Cygwin (1.5.5) and using g++ 3.3.1 ("g++ (GCC) 3.3.1 (cygming special)") 

Using the 3 files below,

$ cat AA1.h
#pragma interface

#include "AA2.h"

class AA1 {
public:
  void g(){
    std::ostringstream os;
  }
};

$ cat AA2.h
#pragma interface

#include <sstream>
#include <iostream>

class AA2 {
 public:
  void f(std::ostringstream os) {
    os.str();
  }
};

$ cat BB.cpp
#include "AA1.h"

#pragma implementation "AA1.h"
#pragma implementation "AA2.h"

int myi;

A compilation results in two bogus undefined
symbols.
$ g++ -c BB.cpp  ; nm BB.o | grep ' U'
         U __GLOBAL__D_myi
         U __GLOBAL__I_myi

It works flawlessly under Linux.

This snippet comes from compiling ddd under cygwin.
Similar problems have been reported. See:
http://www.cygwin.com/ml/cygwin/2003-11/msg01066.html

-- 
           Summary: #pragma interface/implementation lead to link problems
                    on Cygwin
           Product: gcc
           Version: 3.3.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: arnaud dot desitter at ouce dot ox dot ac dot uk
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i686-pc-cygwin
  GCC host triplet: i686-pc-cygwin
GCC target triplet: i686-pc-cygwin


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13420