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* [Bug c++/114549] New: GCC >= 10.1 selects the wrong overload of C++20 reversed operator== function
@ 2024-04-01 17:28 cpeterson at mozilla dot com
2024-04-01 17:33 ` [Bug c++/114549] [11/12/13 Regression] " pinskia at gcc dot gnu.org
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: cpeterson at mozilla dot com @ 2024-04-01 17:28 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114549
Bug ID: 114549
Summary: GCC >= 10.1 selects the wrong overload of C++20
reversed operator== function
Product: gcc
Version: 10.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: cpeterson at mozilla dot com
Target Milestone: ---
While updating Firefox from -std=c++17 to -std=c++20, I found a case where
GCC's resolution of C++20 reversed operator== functions behaves differently
from the Clang, MSVC, and ICX compilers. This is Firefox bug
https://bugzilla.mozilla.org/show_bug.cgi?id=1880776
I believe this difference was a regression in GCC 10.1.
Here's a Godbolt test case comparing those compilers' output:
https://godbolt.org/z/qneax5oaW
```
#include <type_traits>
struct Thing {
template <typename T>
bool operator==(const T& rhs) const {
/* This operator== is selected by:
* GCC versions >= 10.1 -std=c++17
* GCC version 9.5 -std=c++2a
* Clang 18.1 -std=c++2a
* MSVC 19.38 -std=c++20
* Intel's ICX 2024.0.0 -std=c++20
*/
return false;
}
};
template <typename T>
bool operator==(T const& lhs, Thing const& rhs) {
/* This operator== is selected by:
* GCC versions >= 10.1 -std=c++2a
*/
return true;
}
bool test() {
Thing const v{};
return v == 3;
}
```
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/114549] [11/12/13 Regression] GCC >= 10.1 selects the wrong overload of C++20 reversed operator== function
2024-04-01 17:28 [Bug c++/114549] New: GCC >= 10.1 selects the wrong overload of C++20 reversed operator== function cpeterson at mozilla dot com
@ 2024-04-01 17:33 ` pinskia at gcc dot gnu.org
2024-04-01 17:41 ` cpeterson at mozilla dot com
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu.org @ 2024-04-01 17:33 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114549
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Known to fail| |10.1.0, 13.1.0, 13.2.0
Summary|GCC >= 10.1 selects the |[11/12/13 Regression] GCC
|wrong overload of C++20 |>= 10.1 selects the wrong
|reversed operator== |overload of C++20 reversed
|function |operator== function
Target Milestone|--- |11.5
Keywords| |needs-bisection
Known to work| |14.0
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Looks to be fixed on the trunk though.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/114549] [11/12/13 Regression] GCC >= 10.1 selects the wrong overload of C++20 reversed operator== function
2024-04-01 17:28 [Bug c++/114549] New: GCC >= 10.1 selects the wrong overload of C++20 reversed operator== function cpeterson at mozilla dot com
2024-04-01 17:33 ` [Bug c++/114549] [11/12/13 Regression] " pinskia at gcc dot gnu.org
@ 2024-04-01 17:41 ` cpeterson at mozilla dot com
2024-04-01 17:44 ` pinskia at gcc dot gnu.org
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: cpeterson at mozilla dot com @ 2024-04-01 17:41 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114549
Chris Peterson <cpeterson at mozilla dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution|--- |FIXED
--- Comment #2 from Chris Peterson <cpeterson at mozilla dot com> ---
> Looks to be fixed on the trunk though.
Thanks for verifying! I see now on godbolt.org that this bug is fixed in GCC
trunk (though GCC 13.2.0 still has the bug). In that case, I will resolve this
bug as fixed.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/114549] [11/12/13 Regression] GCC >= 10.1 selects the wrong overload of C++20 reversed operator== function
2024-04-01 17:28 [Bug c++/114549] New: GCC >= 10.1 selects the wrong overload of C++20 reversed operator== function cpeterson at mozilla dot com
2024-04-01 17:33 ` [Bug c++/114549] [11/12/13 Regression] " pinskia at gcc dot gnu.org
2024-04-01 17:41 ` cpeterson at mozilla dot com
@ 2024-04-01 17:44 ` pinskia at gcc dot gnu.org
2024-04-01 17:49 ` mpolacek at gcc dot gnu.org
2024-04-02 11:32 ` rguenth at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu.org @ 2024-04-01 17:44 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114549
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2024-04-01
Resolution|FIXED |---
Status|RESOLVED |NEW
Ever confirmed|0 |1
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Chris Peterson from comment #2)
> > Looks to be fixed on the trunk though.
>
> Thanks for verifying! I see now on godbolt.org that this bug is fixed in GCC
> trunk (though GCC 13.2.0 still has the bug). In that case, I will resolve
> this bug as fixed.
It was a regression on the other releases so let's leave it open until it is
fixed on the release branches or decided it is too hard to do as such.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/114549] [11/12/13 Regression] GCC >= 10.1 selects the wrong overload of C++20 reversed operator== function
2024-04-01 17:28 [Bug c++/114549] New: GCC >= 10.1 selects the wrong overload of C++20 reversed operator== function cpeterson at mozilla dot com
` (2 preceding siblings ...)
2024-04-01 17:44 ` pinskia at gcc dot gnu.org
@ 2024-04-01 17:49 ` mpolacek at gcc dot gnu.org
2024-04-02 11:32 ` rguenth at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: mpolacek at gcc dot gnu.org @ 2024-04-01 17:49 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114549
Marek Polacek <mpolacek at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |mpolacek at gcc dot gnu.org
Keywords|needs-bisection |
--- Comment #4 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Looks like it's changed in r14-6221. Doesn't look backportable.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/114549] [11/12/13 Regression] GCC >= 10.1 selects the wrong overload of C++20 reversed operator== function
2024-04-01 17:28 [Bug c++/114549] New: GCC >= 10.1 selects the wrong overload of C++20 reversed operator== function cpeterson at mozilla dot com
` (3 preceding siblings ...)
2024-04-01 17:49 ` mpolacek at gcc dot gnu.org
@ 2024-04-02 11:32 ` rguenth at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: rguenth at gcc dot gnu.org @ 2024-04-02 11:32 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114549
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Priority|P3 |P2
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2024-04-02 11:32 UTC | newest]
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2024-04-01 17:28 [Bug c++/114549] New: GCC >= 10.1 selects the wrong overload of C++20 reversed operator== function cpeterson at mozilla dot com
2024-04-01 17:33 ` [Bug c++/114549] [11/12/13 Regression] " pinskia at gcc dot gnu.org
2024-04-01 17:41 ` cpeterson at mozilla dot com
2024-04-01 17:44 ` pinskia at gcc dot gnu.org
2024-04-01 17:49 ` mpolacek at gcc dot gnu.org
2024-04-02 11:32 ` rguenth at gcc dot gnu.org
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