[Bug c++/13146] New: inheritance for nonoverlapping_component_refs_p

[dann at godzilla dot ics dot uci dot edu]

Currently g++ cannot tell that accesses to class members from different points
of the inheritance hierachy cannot overlap. 

There is a patch that fixes the problem at:

http://gcc.gnu.org/ml/gcc-patches/2002-05/msg01996.html

but it seems that has been forgotten. This bug was created so that the issue 
is not completely forgotten.

A testcase is below. It would be nice if a C++ specialist would 
add more tests.

/* { dg-do link } */

class first
{
public:
  double d;
  int f1;
};

class middle : public first
{
};

class second : public middle
{
public:
  int f2;
  short a;
};

class third
{
public:
  char a;
  char b;
};

class multi: public third, public second
{
public:
  short s;
  char f3;
};

extern void link_error ();

void
foo (first *s1, second *s2)
{
  s1->f1 = 0;
  s2->f2 = 0;
  s1->f1++;
  s2->f2++;
  s1->f1++;
  s2->f2++;
  if (s1->f1 != 2)
    link_error ();
}

void
bar (first *s1, multi *s3)
{
  s1->f1 = 0;
  s3->f3 = 0;
  s1->f1++;
  s3->f3++;
  s1->f1++;
  s3->f3++;
  if (s1->f1 != 2)
    link_error ();
}


int
main()
{
  first a;
  second b;
  multi c;
  foo (&a, &b);
  bar (&a, &c);
  return 0;
}

-- 
           Summary: inheritance for nonoverlapping_component_refs_p
           Product: gcc
           Version: 3.4
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: dann at godzilla dot ics dot uci dot edu
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13146