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* [Bug c++/102013] New: Incorrect aggregate initialization of union
@ 2021-08-22 16:11 fchelnokov at gmail dot com
2021-08-23 9:05 ` [Bug c++/102013] " rguenth at gcc dot gnu.org
2021-08-23 23:06 ` pinskia at gcc dot gnu.org
0 siblings, 2 replies; 3+ messages in thread
From: fchelnokov at gmail dot com @ 2021-08-22 16:11 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102013
Bug ID: 102013
Summary: Incorrect aggregate initialization of union
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: fchelnokov at gmail dot com
Target Milestone: ---
In this program:
```
#include <iostream>
struct A { int x = 1; };
struct B { int x = 0; };
union U {
A a;
B b;
};
int main() {
U u{};
std::cout << u.a.x;
}
```
GCC prints `0`: https://gcc.godbolt.org/z/8Tj4Y1Pv1
But the correct result is `1`, which is the default initializer of the first
union member `a` (see Clang 's result)
^ permalink raw reply [flat|nested] 3+ messages in thread* [Bug c++/102013] Incorrect aggregate initialization of union 2021-08-22 16:11 [Bug c++/102013] New: Incorrect aggregate initialization of union fchelnokov at gmail dot com @ 2021-08-23 9:05 ` rguenth at gcc dot gnu.org 2021-08-23 23:06 ` pinskia at gcc dot gnu.org 1 sibling, 0 replies; 3+ messages in thread From: rguenth at gcc dot gnu.org @ 2021-08-23 9:05 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102013 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Last reconfirmed| |2021-08-23 Keywords| |wrong-code Ever confirmed|0 |1 --- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> --- GCC seems to consider U POD and simply emits <<cleanup_point union U u = {};>>; for the NSDMI ^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug c++/102013] Incorrect aggregate initialization of union 2021-08-22 16:11 [Bug c++/102013] New: Incorrect aggregate initialization of union fchelnokov at gmail dot com 2021-08-23 9:05 ` [Bug c++/102013] " rguenth at gcc dot gnu.org @ 2021-08-23 23:06 ` pinskia at gcc dot gnu.org 1 sibling, 0 replies; 3+ messages in thread From: pinskia at gcc dot gnu.org @ 2021-08-23 23:06 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102013 --- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- This is interesting: struct A { int x = 6; }; struct B { int x = 3; }; union U { A a; B b; }; static_assert (U{}.a.x==6); U a{}; int main() { if (a.a.x != 6) __builtin_abort(); } The static_assert works .... ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-08-23 23:06 UTC | newest] Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-08-22 16:11 [Bug c++/102013] New: Incorrect aggregate initialization of union fchelnokov at gmail dot com 2021-08-23 9:05 ` [Bug c++/102013] " rguenth at gcc dot gnu.org 2021-08-23 23:06 ` pinskia at gcc dot gnu.org
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