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* [Bug c++/94716] New: Address of constexpr variable not usable in constant expression
@ 2020-04-22 15:36 bluescarni at gmail dot com
2020-04-23 5:14 ` [Bug c++/94716] " marxin at gcc dot gnu.org
` (6 more replies)
0 siblings, 7 replies; 8+ messages in thread
From: bluescarni at gmail dot com @ 2020-04-22 15:36 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94716
Bug ID: 94716
Summary: Address of constexpr variable not usable in constant
expression
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: bluescarni at gmail dot com
Target Milestone: ---
The following code does not compile in GCC trunk:
-----
template <typename T>
inline constexpr char test_impl = 0;
template <typename T>
inline constexpr auto *id = &test_impl<T>;
int main() {
static_assert(id<int> != id<float>, "should not be equal");
}
-----
The error message:
-----
<source>: In function 'int main()':
<source>:8:27: error: non-constant condition for static assertion
8 | static_assert(id<int> != id<float>, "should not be equal");
| ~~~~~~~~^~~~~~~~~~~~
<source>:8:27: error: '((& test_impl<int>) != (& test_impl<float>))' is not a
constant expression
Compiler returned: 1
-----
See on godbolt:
https://godbolt.org/z/CS4D8B
Clang and MSVC accept the code.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug c++/94716] Address of constexpr variable not usable in constant expression
2020-04-22 15:36 [Bug c++/94716] New: Address of constexpr variable not usable in constant expression bluescarni at gmail dot com
@ 2020-04-23 5:14 ` marxin at gcc dot gnu.org
2021-08-28 22:27 ` [Bug c++/94716] comparison of address of template variables should be constexpr pinskia at gcc dot gnu.org
` (5 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: marxin at gcc dot gnu.org @ 2020-04-23 5:14 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94716
Martin Liška <marxin at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |rejects-valid
Status|UNCONFIRMED |NEW
CC| |jason at gcc dot gnu.org,
| |marxin at gcc dot gnu.org,
| |mpolacek at gcc dot gnu.org
Last reconfirmed| |2020-04-23
Ever confirmed|0 |1
--- Comment #1 from Martin Liška <marxin at gcc dot gnu.org> ---
Confirmed, ale GCC versions suffer.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug c++/94716] comparison of address of template variables should be constexpr
2020-04-22 15:36 [Bug c++/94716] New: Address of constexpr variable not usable in constant expression bluescarni at gmail dot com
2020-04-23 5:14 ` [Bug c++/94716] " marxin at gcc dot gnu.org
@ 2021-08-28 22:27 ` pinskia at gcc dot gnu.org
2021-09-10 22:46 ` johelegp at gmail dot com
` (4 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-08-28 22:27 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94716
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
See Also| |https://gcc.gnu.org/bugzill
| |a/show_bug.cgi?id=69681
Summary|comparison of address of |comparison of address of
|variables should be |template variables should
|constexpr |be constexpr
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Reduced testcase:
template <int> char test_impl = 0;
static_assert(&test_impl<0> != &test_impl<1>, "should not be equal");
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug c++/94716] comparison of address of template variables should be constexpr
2020-04-22 15:36 [Bug c++/94716] New: Address of constexpr variable not usable in constant expression bluescarni at gmail dot com
2020-04-23 5:14 ` [Bug c++/94716] " marxin at gcc dot gnu.org
2021-08-28 22:27 ` [Bug c++/94716] comparison of address of template variables should be constexpr pinskia at gcc dot gnu.org
@ 2021-09-10 22:46 ` johelegp at gmail dot com
2021-12-28 10:40 ` pinskia at gcc dot gnu.org
` (3 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: johelegp at gmail dot com @ 2021-09-10 22:46 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94716
Johel Ernesto Guerrero Peña <johelegp at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |johelegp at gmail dot com
--- Comment #3 from Johel Ernesto Guerrero Peña <johelegp at gmail dot com> ---
*** Bug 102267 has been marked as a duplicate of this bug. ***
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug c++/94716] comparison of address of template variables should be constexpr
2020-04-22 15:36 [Bug c++/94716] New: Address of constexpr variable not usable in constant expression bluescarni at gmail dot com
` (2 preceding siblings ...)
2021-09-10 22:46 ` johelegp at gmail dot com
@ 2021-12-28 10:40 ` pinskia at gcc dot gnu.org
2022-01-03 12:48 ` cvs-commit at gcc dot gnu.org
` (2 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-12-28 10:40 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94716
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |DUPLICATE
Status|NEW |RESOLVED
--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Dup of bug 91693.
*** This bug has been marked as a duplicate of bug 91693 ***
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug c++/94716] comparison of address of template variables should be constexpr
2020-04-22 15:36 [Bug c++/94716] New: Address of constexpr variable not usable in constant expression bluescarni at gmail dot com
` (3 preceding siblings ...)
2021-12-28 10:40 ` pinskia at gcc dot gnu.org
@ 2022-01-03 12:48 ` cvs-commit at gcc dot gnu.org
2022-01-04 19:15 ` ppalka at gcc dot gnu.org
2022-01-06 16:17 ` ppalka at gcc dot gnu.org
6 siblings, 0 replies; 8+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2022-01-03 12:48 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94716
--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:
https://gcc.gnu.org/g:91031bffa42fdea3c985727d042cd1882a64be9c
commit r12-6188-g91031bffa42fdea3c985727d042cd1882a64be9c
Author: Jakub Jelinek <jakub@redhat.com>
Date: Mon Jan 3 13:47:53 2022 +0100
symtab: Fold &a == &b to 0 if folding_initializer [PR94716]
On Thu, Dec 09, 2021 at 06:09:12PM -0500, Jason Merrill wrote:
> For the more general comparison of decls like your a != b example above I
> think clang is in the right; in manifestly constant-evaluated context
> (folding_initializer) we should return that they are unequal and prevent
a
> later alias declaration, like we do for comparison to 0 in
> maybe_nonzero_address. It's possible that this gives a wrong answer
based
> on something in another translation unit, but that's unlikely, and taking
> that chance seems better than rejecting code that needs a constant
answer.
I agree. This is an incremental patch to do that.
2022-01-03 Jakub Jelinek <jakub@redhat.com>
PR c++/94716
gcc/
* symtab.c: Include fold-const.h.
(symtab_node::equal_address_to): If folding_initializer is true,
handle it like memory_accessed. Simplify.
gcc/testsuite/
* gcc.dg/init-compare-1.c: New test.
* g++.dg/cpp0x/constexpr-compare1.C: New test.
* g++.dg/cpp1y/constexpr-94716.C: New test.
* g++.dg/cpp1z/constexpr-compare1.C: New test.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug c++/94716] comparison of address of template variables should be constexpr
2020-04-22 15:36 [Bug c++/94716] New: Address of constexpr variable not usable in constant expression bluescarni at gmail dot com
` (4 preceding siblings ...)
2022-01-03 12:48 ` cvs-commit at gcc dot gnu.org
@ 2022-01-04 19:15 ` ppalka at gcc dot gnu.org
2022-01-06 16:17 ` ppalka at gcc dot gnu.org
6 siblings, 0 replies; 8+ messages in thread
From: ppalka at gcc dot gnu.org @ 2022-01-04 19:15 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94716
Patrick Palka <ppalka at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |sjeltsch at gmail dot com
--- Comment #6 from Patrick Palka <ppalka at gcc dot gnu.org> ---
*** Bug 101622 has been marked as a duplicate of this bug. ***
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug c++/94716] comparison of address of template variables should be constexpr
2020-04-22 15:36 [Bug c++/94716] New: Address of constexpr variable not usable in constant expression bluescarni at gmail dot com
` (5 preceding siblings ...)
2022-01-04 19:15 ` ppalka at gcc dot gnu.org
@ 2022-01-06 16:17 ` ppalka at gcc dot gnu.org
6 siblings, 0 replies; 8+ messages in thread
From: ppalka at gcc dot gnu.org @ 2022-01-06 16:17 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94716
Patrick Palka <ppalka at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |pdimov at gmail dot com
--- Comment #7 from Patrick Palka <ppalka at gcc dot gnu.org> ---
*** Bug 86354 has been marked as a duplicate of this bug. ***
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2022-01-06 16:17 UTC | newest]
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2020-04-22 15:36 [Bug c++/94716] New: Address of constexpr variable not usable in constant expression bluescarni at gmail dot com
2020-04-23 5:14 ` [Bug c++/94716] " marxin at gcc dot gnu.org
2021-08-28 22:27 ` [Bug c++/94716] comparison of address of template variables should be constexpr pinskia at gcc dot gnu.org
2021-09-10 22:46 ` johelegp at gmail dot com
2021-12-28 10:40 ` pinskia at gcc dot gnu.org
2022-01-03 12:48 ` cvs-commit at gcc dot gnu.org
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