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* [Bug c++/107782] New: constexpr volatile variable is permitted to appear in a constant expression
@ 2022-11-21 7:26 fchelnokov at gmail dot com
2022-11-21 8:00 ` [Bug c++/107782] a local constexpr volatile variable cannot be used to initialize a local constexpr volatile variable pinskia at gcc dot gnu.org
0 siblings, 1 reply; 2+ messages in thread
From: fchelnokov at gmail dot com @ 2022-11-21 7:26 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107782
Bug ID: 107782
Summary: constexpr volatile variable is permitted to appear in
a constant expression
Product: gcc
Version: 12.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: fchelnokov at gmail dot com
Target Milestone: ---
This program
int main() {
constexpr volatile int i = 0;
constexpr volatile int j = i;
return j;
}
is properly rejected by Clang since according to
https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n4093.html#1688
constexpr volatile variable cannot appear in a constant expression.
Unfortunately GCC (and MSVC) accept invalid program. Online demo:
https://gcc.godbolt.org/z/43ee65Peq
Related discussion: https://stackoverflow.com/q/74511594/7325599
^ permalink raw reply [flat|nested] 2+ messages in thread
* [Bug c++/107782] a local constexpr volatile variable cannot be used to initialize a local constexpr volatile variable
2022-11-21 7:26 [Bug c++/107782] New: constexpr volatile variable is permitted to appear in a constant expression fchelnokov at gmail dot com
@ 2022-11-21 8:00 ` pinskia at gcc dot gnu.org
0 siblings, 0 replies; 2+ messages in thread
From: pinskia at gcc dot gnu.org @ 2022-11-21 8:00 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107782
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
See Also|https://gcc.gnu.org/bugzill |
|a/show_bug.cgi?id=87497, |
|https://gcc.gnu.org/bugzill |
|a/show_bug.cgi?id=89553 |
Status|UNCONFIRMED |NEW
Summary|constexpr volatile variable |a local constexpr volatile
|is permitted to appear in a |variable cannot be used to
|constant expression |initialize a local
| |constexpr volatile variable
Last reconfirmed| |2022-11-21
Ever confirmed|0 |1
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.
Note GCC only does NOT rejects the local variable case.
That is take:
int main() {
constexpr volatile int t = 1;
static constexpr volatile int t1 = t;
constexpr volatile int t2 = t;
constexpr int t3 = t;
};
GCC will reject t1 and t3 correctly but not t2.
So GCC is mostly correct except for that one case while MSVC accepts all of the
above.
^ permalink raw reply [flat|nested] 2+ messages in thread
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2022-11-21 7:26 [Bug c++/107782] New: constexpr volatile variable is permitted to appear in a constant expression fchelnokov at gmail dot com
2022-11-21 8:00 ` [Bug c++/107782] a local constexpr volatile variable cannot be used to initialize a local constexpr volatile variable pinskia at gcc dot gnu.org
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