* [Bug c++/103480] -Werror=useless-cast with constexpr destructor
2021-11-29 22:51 [Bug c++/103480] New: [10,11,12]Werror=useless-cast with constexpr destructor peeceseven at gmail dot com
@ 2021-11-29 23:06 ` mpolacek at gcc dot gnu.org
2021-11-30 0:11 ` mpolacek at gcc dot gnu.org
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From: mpolacek at gcc dot gnu.org @ 2021-11-29 23:06 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103480
Marek Polacek <mpolacek at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Last reconfirmed| |2021-11-29
CC| |mpolacek at gcc dot gnu.org
Keywords| |diagnostic
Status|UNCONFIRMED |NEW
Summary|[10,11,12]Werror=useless-ca |-Werror=useless-cast with
|st with constexpr |constexpr destructor
|destructor |
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug c++/103480] -Werror=useless-cast with constexpr destructor
2021-11-29 22:51 [Bug c++/103480] New: [10,11,12]Werror=useless-cast with constexpr destructor peeceseven at gmail dot com
2021-11-29 23:06 ` [Bug c++/103480] -Werror=useless-cast " mpolacek at gcc dot gnu.org
@ 2021-11-30 0:11 ` mpolacek at gcc dot gnu.org
2021-11-30 0:46 ` [Bug c++/103480] [10/11/12 Regression] " mpolacek at gcc dot gnu.org
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From: mpolacek at gcc dot gnu.org @ 2021-11-30 0:11 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103480
--- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
namespace std {
template <typename _Tp, int _Nm> struct __array_traits {
typedef _Tp _Type[_Nm];
};
template <typename _Tp, int _Nm> struct array {
__array_traits<_Tp, _Nm>::_Type _M_elems;
};
} // namespace std
struct scope_guard {
constexpr scope_guard(scope_guard &&) {}
template <int count> static auto array(void()) {
std::array<scope_guard, count> r;
return r;
}
scope_guard() = default;
};
void test() { scope_guard::array<2>(test); }
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug c++/103480] [10/11/12 Regression] -Werror=useless-cast with constexpr destructor
2021-11-29 22:51 [Bug c++/103480] New: [10,11,12]Werror=useless-cast with constexpr destructor peeceseven at gmail dot com
2021-11-29 23:06 ` [Bug c++/103480] -Werror=useless-cast " mpolacek at gcc dot gnu.org
2021-11-30 0:11 ` mpolacek at gcc dot gnu.org
@ 2021-11-30 0:46 ` mpolacek at gcc dot gnu.org
2021-11-30 0:52 ` mpolacek at gcc dot gnu.org
` (7 subsequent siblings)
10 siblings, 0 replies; 12+ messages in thread
From: mpolacek at gcc dot gnu.org @ 2021-11-30 0:46 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103480
Marek Polacek <mpolacek at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|-Werror=useless-cast with |[10/11/12 Regression]
|constexpr destructor |-Werror=useless-cast with
| |constexpr destructor
Target Milestone|--- |10.4
Priority|P3 |P2
--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Started with r10-6527:
commit aaa26bf496a646778ac861aed124d960b5bf549f
Author: Jason Merrill <jason@redhat.com>
Date: Sun Jan 26 22:58:32 2020 -0500
c++: Use constexpr to avoid wrong -Wsign-compare (PR90691).
We would like to do constexpr evaluation to avoid false positives on
warnings, but constexpr evaluation can involve function body copying that
changes DECL_UID, which breaks -fcompare-debug. So let's remember
that we need to avoid that.
PR c++/90691
* expr.c (fold_for_warn): Call maybe_constant_value.
* constexpr.c (struct constexpr_ctx): Add uid_sensitive field.
(maybe_constant_value): Add uid_sensitive parm.
(get_fundef_copy): Don't copy if it's true.
(cxx_eval_call_expression): Don't instantiate if it's true.
(cxx_eval_outermost_constant_expr): Likewise.
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug c++/103480] [10/11/12 Regression] -Werror=useless-cast with constexpr destructor
2021-11-29 22:51 [Bug c++/103480] New: [10,11,12]Werror=useless-cast with constexpr destructor peeceseven at gmail dot com
` (2 preceding siblings ...)
2021-11-30 0:46 ` [Bug c++/103480] [10/11/12 Regression] " mpolacek at gcc dot gnu.org
@ 2021-11-30 0:52 ` mpolacek at gcc dot gnu.org
2021-12-30 17:49 ` jakub at gcc dot gnu.org
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From: mpolacek at gcc dot gnu.org @ 2021-11-30 0:52 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103480
--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Add typename to make it C++14:
namespace std {
template <typename _Tp, int _Nm> struct __array_traits {
typedef _Tp _Type[_Nm];
};
template <typename _Tp, int _Nm> struct array {
typename __array_traits<_Tp, _Nm>::_Type _M_elems;
};
} // namespace std
struct scope_guard {
constexpr scope_guard(scope_guard &&) {}
template <int count> static auto array(void()) {
std::array<scope_guard, count> r;
return r;
}
scope_guard() = default;
};
void test() { scope_guard::array<2>(test); }
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug c++/103480] [10/11/12 Regression] -Werror=useless-cast with constexpr destructor
2021-11-29 22:51 [Bug c++/103480] New: [10,11,12]Werror=useless-cast with constexpr destructor peeceseven at gmail dot com
` (3 preceding siblings ...)
2021-11-30 0:52 ` mpolacek at gcc dot gnu.org
@ 2021-12-30 17:49 ` jakub at gcc dot gnu.org
2022-01-12 8:49 ` cvs-commit at gcc dot gnu.org
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From: jakub at gcc dot gnu.org @ 2021-12-30 17:49 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103480
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
Assignee|unassigned at gcc dot gnu.org |jakub at gcc dot gnu.org
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 52095
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52095&action=edit
gcc12-pr103480.patch
Untested patch to fix that.
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug c++/103480] [10/11/12 Regression] -Werror=useless-cast with constexpr destructor
2021-11-29 22:51 [Bug c++/103480] New: [10,11,12]Werror=useless-cast with constexpr destructor peeceseven at gmail dot com
` (4 preceding siblings ...)
2021-12-30 17:49 ` jakub at gcc dot gnu.org
@ 2022-01-12 8:49 ` cvs-commit at gcc dot gnu.org
2022-01-12 8:53 ` [Bug c++/103480] [10/11 " jakub at gcc dot gnu.org
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From: cvs-commit at gcc dot gnu.org @ 2022-01-12 8:49 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103480
--- 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:6bba184ccbf47368eaea27ee2c1e7b850526640b
commit r12-6516-g6bba184ccbf47368eaea27ee2c1e7b850526640b
Author: Jakub Jelinek <jakub@redhat.com>
Date: Wed Jan 12 09:47:46 2022 +0100
c++: Silence -Wuseless-cast warnings during move [PR103480]
This is maybe just a shot in the dark, but IMHO we shouldn't be diagnosing
-Wuseless-cast on casts the compiler adds on its own when calling its move
function. We don't seem to warn when user calls std::move either.
We call move on elinit (*NON_LVALUE_EXPR <(struct C[2] &&) &D.2497->b>)[0]
so it is already an xvalue_p and try to static_cast it to struct C &&.
But we don't warn e.g. on std::move (std::move (whatever)).
Fixed by not doing the static cast and just returning expr from move
if expr is already an xvalue.
2022-01-11 Jakub Jelinek <jakub@redhat.com>
Jason Merrill <jason@redhat.com>
PR c++/103480
* tree.c (move): If expr is xvalue_p, just return expr without
build_static_cast.
* g++.dg/warn/Wuseless-cast2.C: New test.
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug c++/103480] [10/11 Regression] -Werror=useless-cast with constexpr destructor
2021-11-29 22:51 [Bug c++/103480] New: [10,11,12]Werror=useless-cast with constexpr destructor peeceseven at gmail dot com
` (5 preceding siblings ...)
2022-01-12 8:49 ` cvs-commit at gcc dot gnu.org
@ 2022-01-12 8:53 ` jakub at gcc dot gnu.org
2022-01-24 9:21 ` cvs-commit at gcc dot gnu.org
` (3 subsequent siblings)
10 siblings, 0 replies; 12+ messages in thread
From: jakub at gcc dot gnu.org @ 2022-01-12 8:53 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103480
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|[10/11/12 Regression] |[10/11 Regression]
|-Werror=useless-cast with |-Werror=useless-cast with
|constexpr destructor |constexpr destructor
--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Fixed on the trunk so far.
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug c++/103480] [10/11 Regression] -Werror=useless-cast with constexpr destructor
2021-11-29 22:51 [Bug c++/103480] New: [10,11,12]Werror=useless-cast with constexpr destructor peeceseven at gmail dot com
` (6 preceding siblings ...)
2022-01-12 8:53 ` [Bug c++/103480] [10/11 " jakub at gcc dot gnu.org
@ 2022-01-24 9:21 ` cvs-commit at gcc dot gnu.org
2022-01-24 9:28 ` [Bug c++/103480] [10 " jakub at gcc dot gnu.org
` (2 subsequent siblings)
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From: cvs-commit at gcc dot gnu.org @ 2022-01-24 9:21 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103480
--- Comment #7 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:
https://gcc.gnu.org/g:cb4998fcdf2ad92fc6323fc4d9bc03299ca8a541
commit r11-9501-gcb4998fcdf2ad92fc6323fc4d9bc03299ca8a541
Author: Jakub Jelinek <jakub@redhat.com>
Date: Wed Jan 12 09:47:46 2022 +0100
c++: Silence -Wuseless-cast warnings during move [PR103480]
This is maybe just a shot in the dark, but IMHO we shouldn't be diagnosing
-Wuseless-cast on casts the compiler adds on its own when calling its move
function. We don't seem to warn when user calls std::move either.
We call move on elinit (*NON_LVALUE_EXPR <(struct C[2] &&) &D.2497->b>)[0]
so it is already an xvalue_p and try to static_cast it to struct C &&.
But we don't warn e.g. on std::move (std::move (whatever)).
Fixed by not doing the static cast and just returning expr from move
if expr is already an xvalue.
2022-01-11 Jakub Jelinek <jakub@redhat.com>
Jason Merrill <jason@redhat.com>
PR c++/103480
* tree.c (move): If expr is xvalue_p, just return expr without
build_static_cast.
* g++.dg/warn/Wuseless-cast2.C: New test.
(cherry picked from commit 6bba184ccbf47368eaea27ee2c1e7b850526640b)
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug c++/103480] [10 Regression] -Werror=useless-cast with constexpr destructor
2021-11-29 22:51 [Bug c++/103480] New: [10,11,12]Werror=useless-cast with constexpr destructor peeceseven at gmail dot com
` (7 preceding siblings ...)
2022-01-24 9:21 ` cvs-commit at gcc dot gnu.org
@ 2022-01-24 9:28 ` jakub at gcc dot gnu.org
2022-05-10 8:22 ` cvs-commit at gcc dot gnu.org
2022-05-10 10:14 ` jakub at gcc dot gnu.org
10 siblings, 0 replies; 12+ messages in thread
From: jakub at gcc dot gnu.org @ 2022-01-24 9:28 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103480
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|[10/11 Regression] |[10 Regression]
|-Werror=useless-cast with |-Werror=useless-cast with
|constexpr destructor |constexpr destructor
--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Fixed for 11.3 too.
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug c++/103480] [10 Regression] -Werror=useless-cast with constexpr destructor
2021-11-29 22:51 [Bug c++/103480] New: [10,11,12]Werror=useless-cast with constexpr destructor peeceseven at gmail dot com
` (8 preceding siblings ...)
2022-01-24 9:28 ` [Bug c++/103480] [10 " jakub at gcc dot gnu.org
@ 2022-05-10 8:22 ` cvs-commit at gcc dot gnu.org
2022-05-10 10:14 ` jakub at gcc dot gnu.org
10 siblings, 0 replies; 12+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2022-05-10 8:22 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103480
--- Comment #9 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:
https://gcc.gnu.org/g:ac26cfeca99c488213eaf76d767ec4470ba3cee9
commit r10-10667-gac26cfeca99c488213eaf76d767ec4470ba3cee9
Author: Jakub Jelinek <jakub@redhat.com>
Date: Wed Jan 12 09:47:46 2022 +0100
c++: Silence -Wuseless-cast warnings during move [PR103480]
This is maybe just a shot in the dark, but IMHO we shouldn't be diagnosing
-Wuseless-cast on casts the compiler adds on its own when calling its move
function. We don't seem to warn when user calls std::move either.
We call move on elinit (*NON_LVALUE_EXPR <(struct C[2] &&) &D.2497->b>)[0]
so it is already an xvalue_p and try to static_cast it to struct C &&.
But we don't warn e.g. on std::move (std::move (whatever)).
Fixed by not doing the static cast and just returning expr from move
if expr is already an xvalue.
2022-01-11 Jakub Jelinek <jakub@redhat.com>
Jason Merrill <jason@redhat.com>
PR c++/103480
* tree.c (move): If expr is xvalue_p, just return expr without
build_static_cast.
* g++.dg/warn/Wuseless-cast2.C: New test.
(cherry picked from commit 6bba184ccbf47368eaea27ee2c1e7b850526640b)
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug c++/103480] [10 Regression] -Werror=useless-cast with constexpr destructor
2021-11-29 22:51 [Bug c++/103480] New: [10,11,12]Werror=useless-cast with constexpr destructor peeceseven at gmail dot com
` (9 preceding siblings ...)
2022-05-10 8:22 ` cvs-commit at gcc dot gnu.org
@ 2022-05-10 10:14 ` jakub at gcc dot gnu.org
10 siblings, 0 replies; 12+ messages in thread
From: jakub at gcc dot gnu.org @ 2022-05-10 10:14 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103480
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution|--- |FIXED
--- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Fixed for 10.4 too.
^ permalink raw reply [flat|nested] 12+ messages in thread