[Bug c++/11750] New: Incorrect virtual method invoked for class hierarchy w/ virtual bases

[Bug c++/11750] New: Incorrect virtual method invoked for class hierarchy w/ virtual bases

[jfischer_5809 at yahoo dot com]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11750

           Summary: Incorrect virtual method invoked for class hierarchy w/
                    virtual bases
           Product: gcc
           Version: 3.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jfischer_5809 at yahoo dot com
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu

Paragraph 10.3/2 in the C++ standard [ISO/IEC 14882:1998] provides the following
code example:

<quote>

struct A {
    virtual void f();
};
struct B : virtual A {
    virtual void f();
};

struct C : B , virtual A {
    using A::f; 
};
void foo() {
    C c; 
    c.f();      // calls B::f, the final overrider
    c.C::f();   // calls A::f because of the using-declaration
}

</quote>

When a similar program is compiled using G++ 3.3, the method call 'c.f()' in
function foo() incorrectly invokes A::f and not B::f as specified in the standard.

<example>
<code main.cpp>
#include <iostream>

struct A {
    virtual void f() { std::cout << "A::f()\n"; }
};
struct B : virtual A {
    virtual void f() { std::cout << "B::f()\n"; }
};
struct C : B, virtual A {
    using A::f;
};

int main()
{
    C c;
    c.f();      // ERROR - Incorrectly invokes A::f
    c.C::f();   // OK - Invokes A::f
}
</code>

<build>
$ g++ main.cpp

$ ldd a.out
        libstdc++.so.5 =>
/usr/local/gcc/3.3/lib/gcc-lib/i686-pc-linux-gnu/3.3/libstdc++.so.5 (0x40017000)
        libm.so.6 => /lib/tls/libm.so.6 (0x400e4000)
        libgcc_s.so.1 =>
/usr/local/gcc/3.3/lib/gcc-lib/i686-pc-linux-gnu/3.3/libgcc_s.so.1 (0x40106000)
        libc.so.6 => /lib/tls/libc.so.6 (0x42000000)
        /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
</build>

<output>
$ ./a.out
A::f()
A::f()
</output>

</example>

[Bug c++/11750] Incorrect virtual method invoked for class hierarchy w/ virtual bases

[pinskia at physics dot uc dot edu]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11750


pinskia at physics dot uc dot edu changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
           Keywords|                            |wrong-code
   Last reconfirmed|0000-00-00 00:00:00         |2003-08-01 19:10:34
               date|                            |


------- Additional Comments From pinskia at physics dot uc dot edu  2003-08-01 19:10 -------
I can confirm this on the mainline (20030801).
ICC 6.0 produces the correct ouput.
Note 2.95.3 produces:
B::f()
B::f()
While 3.0.4 produces:
A::f()
A::f()

[Bug c++/11750] Incorrect virtual method invoked for class hierarchy w/ virtual bases

[dhazeghi at yahoo dot com]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11750


dhazeghi at yahoo dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|3.4                         |---

[Bug c++/11750] Incorrect virtual method invoked for class hierarchy w/ virtual bases

[davi at ppgia dot pucpr dot br]

------- Additional Comments From davi at ppgia dot pucpr dot br  2004-08-05 23:18 -------
A way to workaround this is to put C into the heap. Is anyone going to fix this ?

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11750

[Bug c++/11750] Incorrect virtual method invoked for class hierarchy w/ virtual bases

[giovannibajo at libero dot it]

------- Additional Comments From giovannibajo at libero dot it  2004-08-08 16:33 -------
(In reply to comment #2)

> Is anyone going to fix this ?

I doubt it, at least any time soon. This is not a regression, and our semantic 
of the using declarations should be reworked (right now, they match old ARM-
style access declarations).

If you feel strong about this, you can either try to look into the problem 
yourself, or hire someone to do the work.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11750

[Bug c++/11750] Incorrect virtual method invoked for class hierarchy w/ virtual bases

[pinskia at gcc dot gnu dot org]

------- Comment #5 from pinskia at gcc dot gnu dot org  2006-09-19 09:41 -------
*** Bug 29136 has been marked as a duplicate of this bug. ***


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |andrew dot stubbs at st dot
                   |                            |com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11750

[Bug c++/11750] Incorrect virtual method invoked for class hierarchy w/ virtual bases

[pinskia at gcc dot gnu dot org]

------- Comment #4 from pinskia at gcc dot gnu dot org  2006-08-16 04:45 -------
*** Bug 28748 has been marked as a duplicate of this bug. ***


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |alexey dot starovoytov at
                   |                            |sun dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11750