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* [Bug c++/102116] New: structured binding is returned from a function as rvalue in C++20 mode
@ 2021-08-29 9:27 fchelnokov at gmail dot com
2021-09-02 6:46 ` [Bug c++/102116] " fchelnokov at gmail dot com
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: fchelnokov at gmail dot com @ 2021-08-29 9:27 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102116
Bug ID: 102116
Summary: structured binding is returned from a function as
rvalue in C++20 mode
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 the following program:
```
#include <tuple>
#include <iostream>
struct A {
A(const int &) { std::cout << "A(const int &) "; }
A(int &&) { std::cout << "A(int &&) "; }
};
A foo() {
auto [y] = std::make_tuple(1);
return y;
}
int main() { foo(); }
```
GCC selects "A(int &&)" constructor starting from C++20 mode, demo:
https://gcc.godbolt.org/z/5q779vE6T
I asked why on stack-overflow:
https://stackoverflow.com/questions/68941451/shall-structured-binding-be-returned-from-a-function-as-rvalue-in-c20
and the answer was that GCC being wrong here.
Could you please confirm it or explain why the behavior of the program changes
in C++20 mode?
^ permalink raw reply [flat|nested] 5+ messages in thread* [Bug c++/102116] structured binding is returned from a function as rvalue in C++20 mode 2021-08-29 9:27 [Bug c++/102116] New: structured binding is returned from a function as rvalue in C++20 mode fchelnokov at gmail dot com @ 2021-09-02 6:46 ` fchelnokov at gmail dot com 2021-09-02 6:55 ` pinskia at gcc dot gnu.org ` (2 subsequent siblings) 3 siblings, 0 replies; 5+ messages in thread From: fchelnokov at gmail dot com @ 2021-09-02 6:46 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102116 --- Comment #1 from Fedor Chelnokov <fchelnokov at gmail dot com> --- Sorry, what do you mean by "wrong-code" tag? The code example is for sure valid. It may be only unclear which one of two A-constructors must be called. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/102116] structured binding is returned from a function as rvalue in C++20 mode 2021-08-29 9:27 [Bug c++/102116] New: structured binding is returned from a function as rvalue in C++20 mode fchelnokov at gmail dot com 2021-09-02 6:46 ` [Bug c++/102116] " fchelnokov at gmail dot com @ 2021-09-02 6:55 ` pinskia at gcc dot gnu.org 2021-09-02 7:04 ` fchelnokov at gmail dot com 2021-09-02 7:13 ` jakub at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu.org @ 2021-09-02 6:55 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102116 --- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- (In reply to Fedor Chelnokov from comment #1) > Sorry, what do you mean by "wrong-code" tag? The code example is for sure > valid. It may be only unclear which one of two A-constructors must be called. wrong-code keyword means GCC is out putting the wrong thing for the input of valid code. Does that make sense? ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/102116] structured binding is returned from a function as rvalue in C++20 mode 2021-08-29 9:27 [Bug c++/102116] New: structured binding is returned from a function as rvalue in C++20 mode fchelnokov at gmail dot com 2021-09-02 6:46 ` [Bug c++/102116] " fchelnokov at gmail dot com 2021-09-02 6:55 ` pinskia at gcc dot gnu.org @ 2021-09-02 7:04 ` fchelnokov at gmail dot com 2021-09-02 7:13 ` jakub at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: fchelnokov at gmail dot com @ 2021-09-02 7:04 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102116 --- Comment #3 from Fedor Chelnokov <fchelnokov at gmail dot com> --- Thanks a lot, it is clear now. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/102116] structured binding is returned from a function as rvalue in C++20 mode 2021-08-29 9:27 [Bug c++/102116] New: structured binding is returned from a function as rvalue in C++20 mode fchelnokov at gmail dot com ` (2 preceding siblings ...) 2021-09-02 7:04 ` fchelnokov at gmail dot com @ 2021-09-02 7:13 ` jakub at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: jakub at gcc dot gnu.org @ 2021-09-02 7:13 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102116 Jakub Jelinek <jakub at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |jakub at gcc dot gnu.org --- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> --- If you follow the Keywords: hyperlink, you'll get description of all the keywords... ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2021-09-02 7:13 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-08-29 9:27 [Bug c++/102116] New: structured binding is returned from a function as rvalue in C++20 mode fchelnokov at gmail dot com 2021-09-02 6:46 ` [Bug c++/102116] " fchelnokov at gmail dot com 2021-09-02 6:55 ` pinskia at gcc dot gnu.org 2021-09-02 7:04 ` fchelnokov at gmail dot com 2021-09-02 7:13 ` jakub at gcc dot gnu.org
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