* [Bug c++/11750] class scope using-declaration lookup not implemented
[not found] <bug-11750-4@http.gcc.gnu.org/bugzilla/>
@ 2011-01-12 17:06 ` balakrishnan.erode at gmail dot com
2011-01-12 17:20 ` redi at gcc dot gnu.org
` (5 subsequent siblings)
6 siblings, 0 replies; 7+ messages in thread
From: balakrishnan.erode at gmail dot com @ 2011-01-12 17:06 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11750
Balakrishnan B <balakrishnan.erode at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |balakrishnan.erode at gmail
| |dot com
--- Comment #6 from Balakrishnan B <balakrishnan.erode at gmail dot com> 2011-01-12 16:57:07 UTC ---
(In reply to comment #0)
> 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>
Im using g++ 4.4.5
With the same example with my main function as below,
int main()
{
C c;
c.f() // Calls A::f
C* pc = &c;
pc->f() // Calls B::f
}
With the same object when accessed directly produces different results and when
accessed using a pointer of same type produces a different result. Even if gcc
violates standard, there has to be some proper explanation.
^ permalink raw reply [flat|nested] 7+ messages in thread* [Bug c++/11750] class scope using-declaration lookup not implemented
[not found] <bug-11750-4@http.gcc.gnu.org/bugzilla/>
2011-01-12 17:06 ` [Bug c++/11750] class scope using-declaration lookup not implemented balakrishnan.erode at gmail dot com
@ 2011-01-12 17:20 ` redi at gcc dot gnu.org
2011-01-12 18:24 ` aschepler at gmail dot com
` (4 subsequent siblings)
6 siblings, 0 replies; 7+ messages in thread
From: redi at gcc dot gnu.org @ 2011-01-12 17:20 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11750
--- Comment #7 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-01-12 17:10:17 UTC ---
(In reply to comment #6)
>
> With the same object when accessed directly produces different results and when
> accessed using a pointer of same type produces a different result. Even if gcc
> violates standard, there has to be some proper explanation.
The explanation is "it's a bug"
^ permalink raw reply [flat|nested] 7+ messages in thread* [Bug c++/11750] class scope using-declaration lookup not implemented
[not found] <bug-11750-4@http.gcc.gnu.org/bugzilla/>
2011-01-12 17:06 ` [Bug c++/11750] class scope using-declaration lookup not implemented balakrishnan.erode at gmail dot com
2011-01-12 17:20 ` redi at gcc dot gnu.org
@ 2011-01-12 18:24 ` aschepler at gmail dot com
2011-11-21 22:32 ` fabien at gcc dot gnu.org
` (3 subsequent siblings)
6 siblings, 0 replies; 7+ messages in thread
From: aschepler at gmail dot com @ 2011-01-12 18:24 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11750
--- Comment #8 from Andrew Schepler <aschepler at gmail dot com> 2011-01-12 17:16:29 UTC ---
(In reply to comment #6)
> > struct A {
> > virtual void f();
> > };
> > struct B : virtual A {
> > virtual void f();
> > };
> >
> > struct C : B , virtual A {
> > using A::f;
> > };
> Im using g++ 4.4.5
> With the same example with my main function as below,
> int main()
> {
> C c;
> c.f() // Calls A::f
> C* pc = &c;
> pc->f() // Calls B::f
> }
>
> With the same object when accessed directly produces different results and when
> accessed using a pointer of same type produces a different result. Even if gcc
> violates standard, there has to be some proper explanation.
The reason is that when f is invoked via a pointer or reference, g++ uses the
vtable lookup to call the correct final override. But when the object in the
member access is not a pointer or reference (it is a non-reference identifier
as here, or qualified id, or class member), g++ can usually optimize away the
virtual call and just call the correct member function. In this case the logic
for calling the correct member function for that optimization is incorrect, but
virtual calls still work correctly.
^ permalink raw reply [flat|nested] 7+ messages in thread* [Bug c++/11750] class scope using-declaration lookup not implemented
[not found] <bug-11750-4@http.gcc.gnu.org/bugzilla/>
` (2 preceding siblings ...)
2011-01-12 18:24 ` aschepler at gmail dot com
@ 2011-11-21 22:32 ` fabien at gcc dot gnu.org
2012-11-14 20:13 ` fabien at gcc dot gnu.org
` (2 subsequent siblings)
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From: fabien at gcc dot gnu.org @ 2011-11-21 22:32 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11750
fabien at gcc dot gnu.org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
Last reconfirmed|2005-12-18 20:22:49 |2011-11-21 20:22:49
^ permalink raw reply [flat|nested] 7+ messages in thread* [Bug c++/11750] class scope using-declaration lookup not implemented
[not found] <bug-11750-4@http.gcc.gnu.org/bugzilla/>
` (3 preceding siblings ...)
2011-11-21 22:32 ` fabien at gcc dot gnu.org
@ 2012-11-14 20:13 ` fabien at gcc dot gnu.org
2012-11-14 20:20 ` fabien at gcc dot gnu.org
2021-08-02 0:15 ` pinskia at gcc dot gnu.org
6 siblings, 0 replies; 7+ messages in thread
From: fabien at gcc dot gnu.org @ 2012-11-14 20:13 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11750
--- Comment #9 from fabien at gcc dot gnu.org 2012-11-14 20:12:56 UTC ---
Author: fabien
Date: Wed Nov 14 20:12:47 2012
New Revision: 193504
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=193504
Log:
gcc/testsuite/ChangeLog
2012-11-14 Fabien Chêne <fabien@gcc.gnu.org>
PR c++/11750
* g++.dg/inherit/vitual9.C: New.
gcc/cp/ChangeLog
2012-11-14 Fabien Chêne <fabien@gcc.gnu.org>
PR c++/11750
* call.c (build_new_method_call_1): Check that the instance type
and the function context are the same before setting the flag
LOOKUP_NONVIRTUAL.
Added:
trunk/gcc/testsuite/g++.dg/inherit/virtual9.C
Modified:
trunk/gcc/cp/ChangeLog
trunk/gcc/cp/call.c
trunk/gcc/testsuite/ChangeLog
^ permalink raw reply [flat|nested] 7+ messages in thread* [Bug c++/11750] class scope using-declaration lookup not implemented
[not found] <bug-11750-4@http.gcc.gnu.org/bugzilla/>
` (4 preceding siblings ...)
2012-11-14 20:13 ` fabien at gcc dot gnu.org
@ 2012-11-14 20:20 ` fabien at gcc dot gnu.org
2021-08-02 0:15 ` pinskia at gcc dot gnu.org
6 siblings, 0 replies; 7+ messages in thread
From: fabien at gcc dot gnu.org @ 2012-11-14 20:20 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11750
fabien at gcc dot gnu.org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution| |FIXED
Target Milestone|--- |4.8.0
--- Comment #10 from fabien at gcc dot gnu.org 2012-11-14 20:20:21 UTC ---
Fixed in 4.8.
^ permalink raw reply [flat|nested] 7+ messages in thread* [Bug c++/11750] class scope using-declaration lookup not implemented
[not found] <bug-11750-4@http.gcc.gnu.org/bugzilla/>
` (5 preceding siblings ...)
2012-11-14 20:20 ` fabien at gcc dot gnu.org
@ 2021-08-02 0:15 ` pinskia at gcc dot gnu.org
6 siblings, 0 replies; 7+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-08-02 0:15 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=11750
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |meng at g dot clemson.edu
--- Comment #11 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 55385 has been marked as a duplicate of this bug. ***
^ permalink raw reply [flat|nested] 7+ messages in thread