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* [Bug c++/108223] New: GCC reject QNaN in constant expressions
@ 2022-12-25 15:04 nikolasklauser at berlin dot de
2022-12-25 18:30 ` [Bug c++/108223] GCC rejects " pinskia at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: nikolasklauser at berlin dot de @ 2022-12-25 15:04 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108223
Bug ID: 108223
Summary: GCC reject QNaN in constant expressions
Product: gcc
Version: 12.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: nikolasklauser at berlin dot de
Target Milestone: ---
GCC rejects the following code with "error: '__builtin_fmax(+QNaN, +QNaN)' is
not a constant expression" even though it's perfectly defined behaviour.
test code (Godbolt: https://godbolt.org/z/1hfxM9PEW):
constexpr bool test() {
auto val = __builtin_fmax(__builtin_nan(""), __builtin_nan(""));
return true;
}
static_assert(test());
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/108223] GCC rejects QNaN in constant expressions
2022-12-25 15:04 [Bug c++/108223] New: GCC reject QNaN in constant expressions nikolasklauser at berlin dot de
@ 2022-12-25 18:30 ` pinskia at gcc dot gnu.org
2022-12-25 18:33 ` [Bug c++/108223] GCC rejects QNaN in __builtin_fmax constant expression pinskia at gcc dot gnu.org
2022-12-25 18:38 ` nikolasklauser at berlin dot de
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2022-12-25 18:30 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108223
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
__builtin_fmax does not have to be a constant expression as it is an extension
...
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/108223] GCC rejects QNaN in __builtin_fmax constant expression
2022-12-25 15:04 [Bug c++/108223] New: GCC reject QNaN in constant expressions nikolasklauser at berlin dot de
2022-12-25 18:30 ` [Bug c++/108223] GCC rejects " pinskia at gcc dot gnu.org
@ 2022-12-25 18:33 ` pinskia at gcc dot gnu.org
2022-12-25 18:38 ` nikolasklauser at berlin dot de
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2022-12-25 18:33 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108223
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
That being said this works:
#include <cmath>
constexpr bool test() {
auto val = std::max(__builtin_nan(""), __builtin_nan(""));
return true;
}
static_assert(test());
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/108223] GCC rejects QNaN in __builtin_fmax constant expression
2022-12-25 15:04 [Bug c++/108223] New: GCC reject QNaN in constant expressions nikolasklauser at berlin dot de
2022-12-25 18:30 ` [Bug c++/108223] GCC rejects " pinskia at gcc dot gnu.org
2022-12-25 18:33 ` [Bug c++/108223] GCC rejects QNaN in __builtin_fmax constant expression pinskia at gcc dot gnu.org
@ 2022-12-25 18:38 ` nikolasklauser at berlin dot de
2 siblings, 0 replies; 4+ messages in thread
From: nikolasklauser at berlin dot de @ 2022-12-25 18:38 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108223
--- Comment #3 from Nikolas Klauser <nikolasklauser at berlin dot de> ---
It doesn't have to work, but it works for some inputs, so I would expect that
it works for all. https://godbolt.org/z/KsrjEP77c
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2022-12-25 18:39 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2022-12-25 15:04 [Bug c++/108223] New: GCC reject QNaN in constant expressions nikolasklauser at berlin dot de
2022-12-25 18:30 ` [Bug c++/108223] GCC rejects " pinskia at gcc dot gnu.org
2022-12-25 18:33 ` [Bug c++/108223] GCC rejects QNaN in __builtin_fmax constant expression pinskia at gcc dot gnu.org
2022-12-25 18:38 ` nikolasklauser at berlin dot de
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