c++/3706: covariant returns and virtual inheritance

[j.hannemann@ieee.org]

>Number:         3706
>Category:       c++
>Synopsis:       covariant returns and virtual inheritance
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          rejects-legal
>Submitter-Id:   net
>Arrival-Date:   Tue Jul 17 02:46:04 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:     Jens Hannemann
>Release:        3.0
>Organization:
>Environment:
System: SunOS dortmund 5.6 Generic_105181-05 sun4u sparc SUNW,Ultra-60
Architecture: sun4
host: sparc-sun-solaris2.6
build: sparc-sun-solaris2.6
target: sparc-sun-solaris2.6
configured with: ../gcc-3.0/configure --prefix=/usr/local/gcc3
>Description:
When using covariant returns (such as in "virtual constructors")
in conjunction with virtual inheritance, g++ gives the error:
"foo.cpp:8: sorry, not implemented: adjusting pointers for covariant returns"
Behavior for non-virtual inheritance is correct.
I tried this with gcc 2.95.3, gcc 3.0 and the latest snapshot using CodeSourcery's
online compiler as of July 17, 2001.
>How-To-Repeat:
class A
{
  public:
  virtual A* clone() const = 0;
};
 
class B: public virtual A
{
  public:
  virtual B* clone() const {return(new B(*this));}
};
 
int main()
{
  B* b = new B;
  B* c = b->clone();
  return 0;
}
>Fix:

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