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* [Bug c++/109235] New: nodiscard attribute ignored with deduction guide
@ 2023-03-21 15:23 tejo@bang-olufsen.dk
2023-03-21 15:25 ` [Bug c++/109235] " pinskia at gcc dot gnu.org
` (5 more replies)
0 siblings, 6 replies; 7+ messages in thread
From: tejo@bang-olufsen.dk @ 2023-03-21 15:23 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109235
Bug ID: 109235
Summary: nodiscard attribute ignored with deduction guide
Product: gcc
Version: 12.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: tejo@bang-olufsen.dk
Target Milestone: ---
I have tried implementing std::experimental::scope_exit and since this is a
RAII object, I marked it with [[nodiscard]] to ensure all instances are
assigned to a variable.
It appears, however, that GCC ignores the nodiscard attribute when a deduction
guide is present. See this Godbolt link for an example:
https://godbolt.org/z/v9e8dqW1o
Notice how Clang correctly flags the problem.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/109235] nodiscard attribute ignored with deduction guide
2023-03-21 15:23 [Bug c++/109235] New: nodiscard attribute ignored with deduction guide tejo@bang-olufsen.dk
@ 2023-03-21 15:25 ` pinskia at gcc dot gnu.org
2023-03-21 15:29 ` [Bug c++/109235] nodiscard attribute ignored on temporary created pinskia at gcc dot gnu.org
` (4 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-03-21 15:25 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109235
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Created attachment 54721
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=54721&action=edit
Full testcase with -std=c++20
Please attach the testcase next time or put it inline and not just a link to
godbolt .
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/109235] nodiscard attribute ignored on temporary created
2023-03-21 15:23 [Bug c++/109235] New: nodiscard attribute ignored with deduction guide tejo@bang-olufsen.dk
2023-03-21 15:25 ` [Bug c++/109235] " pinskia at gcc dot gnu.org
@ 2023-03-21 15:29 ` pinskia at gcc dot gnu.org
2023-03-21 15:30 ` [Bug c++/109235] nodiscard attribute on class not copied to the constructors pinskia at gcc dot gnu.org
` (3 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-03-21 15:29 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109235
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |diagnostic
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
Last reconfirmed| |2023-03-21
Summary|nodiscard attribute ignored |nodiscard attribute ignored
|with deduction guide |on temporary created
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This has nothing to do with deduction guides either.
Reduced testcase:
```
struct [[nodiscard]] scope_exit {
scope_exit(int);
};
int main()
{
scope_exit{0};
}
```
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/109235] nodiscard attribute on class not copied to the constructors
2023-03-21 15:23 [Bug c++/109235] New: nodiscard attribute ignored with deduction guide tejo@bang-olufsen.dk
2023-03-21 15:25 ` [Bug c++/109235] " pinskia at gcc dot gnu.org
2023-03-21 15:29 ` [Bug c++/109235] nodiscard attribute ignored on temporary created pinskia at gcc dot gnu.org
@ 2023-03-21 15:30 ` pinskia at gcc dot gnu.org
2023-03-21 15:31 ` pinskia at gcc dot gnu.org
` (2 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-03-21 15:30 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109235
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|nodiscard attribute ignored |nodiscard attribute on
|on temporary created |class not copied to the
| |constructors
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
If we move the nodiscard to the constructor, GCC errors out correctly.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/109235] nodiscard attribute on class not copied to the constructors
2023-03-21 15:23 [Bug c++/109235] New: nodiscard attribute ignored with deduction guide tejo@bang-olufsen.dk
` (2 preceding siblings ...)
2023-03-21 15:30 ` [Bug c++/109235] nodiscard attribute on class not copied to the constructors pinskia at gcc dot gnu.org
@ 2023-03-21 15:31 ` pinskia at gcc dot gnu.org
2023-03-21 15:32 ` pinskia at gcc dot gnu.org
2023-03-22 13:30 ` redi at gcc dot gnu.org
5 siblings, 0 replies; 7+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-03-21 15:31 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109235
--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #3)
> If we move the nodiscard to the constructor, GCC errors out correctly.
That is true even on the original testcase.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/109235] nodiscard attribute on class not copied to the constructors
2023-03-21 15:23 [Bug c++/109235] New: nodiscard attribute ignored with deduction guide tejo@bang-olufsen.dk
` (3 preceding siblings ...)
2023-03-21 15:31 ` pinskia at gcc dot gnu.org
@ 2023-03-21 15:32 ` pinskia at gcc dot gnu.org
2023-03-22 13:30 ` redi at gcc dot gnu.org
5 siblings, 0 replies; 7+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-03-21 15:32 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109235
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |DUPLICATE
Status|NEW |RESOLVED
--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Dup of bug 85973.
*** This bug has been marked as a duplicate of bug 85973 ***
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/109235] nodiscard attribute on class not copied to the constructors
2023-03-21 15:23 [Bug c++/109235] New: nodiscard attribute ignored with deduction guide tejo@bang-olufsen.dk
` (4 preceding siblings ...)
2023-03-21 15:32 ` pinskia at gcc dot gnu.org
@ 2023-03-22 13:30 ` redi at gcc dot gnu.org
5 siblings, 0 replies; 7+ messages in thread
From: redi at gcc dot gnu.org @ 2023-03-22 13:30 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109235
--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Teis Johansen from comment #0)
> I have tried implementing std::experimental::scope_exit
N.B. this is already present in the upcoming GCC 13:
https://gcc.gnu.org/gcc-13/changes.html#libstdcxx
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2023-03-22 13:30 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
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2023-03-21 15:23 [Bug c++/109235] New: nodiscard attribute ignored with deduction guide tejo@bang-olufsen.dk
2023-03-21 15:25 ` [Bug c++/109235] " pinskia at gcc dot gnu.org
2023-03-21 15:29 ` [Bug c++/109235] nodiscard attribute ignored on temporary created pinskia at gcc dot gnu.org
2023-03-21 15:30 ` [Bug c++/109235] nodiscard attribute on class not copied to the constructors pinskia at gcc dot gnu.org
2023-03-21 15:31 ` pinskia at gcc dot gnu.org
2023-03-21 15:32 ` pinskia at gcc dot gnu.org
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