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* [Bug c++/105407] New: std::construct_at during constant evaluation does not zero-initialize
@ 2022-04-27 13:48 fchelnokov at gmail dot com
2022-04-27 14:08 ` [Bug c++/105407] " redi at gcc dot gnu.org
0 siblings, 1 reply; 2+ messages in thread
From: fchelnokov at gmail dot com @ 2022-04-27 13:48 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105407
Bug ID: 105407
Summary: std::construct_at during constant evaluation does not
zero-initialize
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: ---
This example program:
```
#include <memory>
#include <iostream>
struct A {
int x = x;
};
constexpr int foo() {
A a{1};
std::construct_at<A>(&a);
return a.x;
}
int main() {
constexpr int v = foo();
std::cout << v << foo();
}
```
shall print "00" (as Clang and MSVC do), because before "x=x" std::construct_at
must zero-initialize (a), see https://eel.is/c++draft/dcl.init#general-9.1.2
GCC prints "10" (demo: https://gcc.godbolt.org/z/eoEr5KMjM) meaning that it
behaves correctly in run-time, but not during constant evaluation.
^ permalink raw reply [flat|nested] 2+ messages in thread
* [Bug c++/105407] std::construct_at during constant evaluation does not zero-initialize
2022-04-27 13:48 [Bug c++/105407] New: std::construct_at during constant evaluation does not zero-initialize fchelnokov at gmail dot com
@ 2022-04-27 14:08 ` redi at gcc dot gnu.org
0 siblings, 0 replies; 2+ messages in thread
From: redi at gcc dot gnu.org @ 2022-04-27 14:08 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105407
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I don't think the zero-init makes x=x OK though.
^ permalink raw reply [flat|nested] 2+ messages in thread
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2022-04-27 13:48 [Bug c++/105407] New: std::construct_at during constant evaluation does not zero-initialize fchelnokov at gmail dot com
2022-04-27 14:08 ` [Bug c++/105407] " redi at gcc dot gnu.org
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