c++/3383: covariant returns types not implemented

[t5 at pobox dot com]

>Number:         3383
>Category:       c++
>Synopsis:       covariant returns types not implemented
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          rejects-legal
>Submitter-Id:   net
>Arrival-Date:   Fri Jun 22 15:06:00 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:     David Jung
>Release:        3.0
>Organization:
>Environment:

>Description:
Trying to compile code that uses a co-variant return type gives the
following message:

sorry, not implemented: adjusting pointers 
   for covariant returns

and exits.
(Although you may be aware of this, I could find a problem report about
it anywhere in GNATS)

>How-To-Repeat:
Comple some code with a covariant return type.

[e.g. see C++ FAQ 20.5

 class Shape {
    public:
      virtual ~Shape() { }                 // A virtual destructor[20.4]
      virtual void draw() = 0;             // A pure virtual function[22.4]
      virtual void move() = 0;
      // ...
      virtual Shape* clone()  const = 0;   // Uses the copy constructor
      virtual Shape* create() const = 0;   // Uses the default constructor[10.4]
    };

    class Circle : public Shape {
    public:
      Circle* clone()  const { return new Circle(*this); }
      Circle* create() const { return new Circle();      }
      // ...
    }

]
>Fix:

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