[Bug c++/11376] [3.3/3.4 regression] mozilla-1.4 miscompiled

["kevin dot hendricks at sympatico dot ca" <gcc-bugzilla at gcc dot gnu dot org>]

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11376



------- Additional Comments From kevin dot hendricks at sympatico dot ca  2003-07-08 00:59 -------
Subject: Re:  [3.3/3.4 regression] mozilla-1.4 miscompiled

Hi,

Thanks for explaining that.  Now that I am aware of which parts
of the program the code generation is sensitive to, I have been able to take 
the test case and hack away the C and Safe classes and remove the getter() 
function and still see the problem.

Here is yet again a smaller testcase and my last so I hope this helps.

I am still not sure if this is an aliasing problem or not.

Perhaps the developer who wrote the nsCOMPtr template class for 
Netscape / Mozilla can provide some insight into this problem?

cat tcase4.cxx

#include <cstdlib>
#include <cstdio>

class Iface {
public:
  virtual int Add(void) = 0;
};


class M : public Iface {
public:
  int i;
  int Add(void) { i++; return i; }
  int SetMutable(int k) { i = k; }
};


class Bbase {
public:
  Bbase( Iface * rawPtr = 0) { a = rawPtr; }
  void assign( Iface * q ) { a = q; }
#ifdef ALL_INTERNAL
  void ** begin_assign()
  {
     assign(0);
     return reinterpret_cast< void **> (&a);
  }
#else
  void ** begin_assign();
#endif
protected:
  Iface * a;
};

#ifndef ALL_INTERNAL
void ** Bbase::begin_assign()
{
   assign(0);
   return reinterpret_cast< void **> (&a);
}
#endif


class B : private Bbase {
public:
  B(): Bbase(0) {}
  B( M* ptr ) : Bbase(ptr) {}
  M** StartAssign() { return reinterpret_cast< M**> (begin_assign()); }
  M* get () const { return reinterpret_cast< M* > (a); }
  operator M*() const { return get(); }
  M* operator->() const { return get(); }
};


int
main(int argc, char** argv)
{
    B b1 = new M();
    Iface * p=static_cast< Iface* >(b1);
    B b2;
    M** retval = b2.StartAssign();
    *retval = static_cast< M* >(p);
    b2->SetMutable(0);
    fprintf(stderr,"done\n"); fflush(stderr);
    return 0;
}