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* [Bug c++/63179] New: Does not work virtuality
@ 2014-09-04 18:46 isak50 at mail dot ru
2014-09-04 21:59 ` [Bug c++/63179] Virtuality is not working redi at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: isak50 at mail dot ru @ 2014-09-04 18:46 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63179
Bug ID: 63179
Summary: Does not work virtuality
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: isak50 at mail dot ru
// g++ 1.cpp -O2 -Wall -std=c++11 -Wall
#include <stdio.h>
struct Base{
virtual void f() {printf("base\n");}
};
struct Child : Base{
void f()override {printf("child\n");}
};
alignas(Child)
char buf[sizeof(Child)];
union Ptr{
decltype(::buf) buf;
Base base;
};
int main(){
new(buf) Child;
Ptr *ptr = reinterpret_cast<Ptr*>(buf);
//-------------------printf: base---//
ptr->base.f(); //
Base &b = ptr->base; //
b.f(); // clang print "child".
//----------------------------------//
//-------------------printf: child--//
Base *b2 = &ptr->base; //
b2->f(); //
//----------------------------------//
}
^ permalink raw reply [flat|nested] 4+ messages in thread* [Bug c++/63179] Virtuality is not working 2014-09-04 18:46 [Bug c++/63179] New: Does not work virtuality isak50 at mail dot ru @ 2014-09-04 21:59 ` redi at gcc dot gnu.org 2014-09-05 6:52 ` isak50 at mail dot ru 2014-09-05 8:42 ` rguenth at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: redi at gcc dot gnu.org @ 2014-09-04 21:59 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63179 --- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> --- I don't think this is valid, the standard says it is OK to access the stored value of the Child object through a union that has a Child member, or to access it through Base, but not through a union that has a Base member. So the program has undefined behaviour and any result is valid. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/63179] Virtuality is not working 2014-09-04 18:46 [Bug c++/63179] New: Does not work virtuality isak50 at mail dot ru 2014-09-04 21:59 ` [Bug c++/63179] Virtuality is not working redi at gcc dot gnu.org @ 2014-09-05 6:52 ` isak50 at mail dot ru 2014-09-05 8:42 ` rguenth at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: isak50 at mail dot ru @ 2014-09-05 6:52 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63179 --- Comment #2 from Pavel <isak50 at mail dot ru> --- Sorry. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/63179] Virtuality is not working 2014-09-04 18:46 [Bug c++/63179] New: Does not work virtuality isak50 at mail dot ru 2014-09-04 21:59 ` [Bug c++/63179] Virtuality is not working redi at gcc dot gnu.org 2014-09-05 6:52 ` isak50 at mail dot ru @ 2014-09-05 8:42 ` rguenth at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: rguenth at gcc dot gnu.org @ 2014-09-05 8:42 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63179 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED Resolution|--- |INVALID --- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> --- . ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2014-09-05 8:42 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2014-09-04 18:46 [Bug c++/63179] New: Does not work virtuality isak50 at mail dot ru 2014-09-04 21:59 ` [Bug c++/63179] Virtuality is not working redi at gcc dot gnu.org 2014-09-05 6:52 ` isak50 at mail dot ru 2014-09-05 8:42 ` rguenth at gcc dot gnu.org
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