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* [Bug c++/102535] New: __is_trivially_constructible rejects some trivial cases in aggregate initializations
@ 2021-09-30 2:45 de34 at live dot cn
2021-09-30 14:59 ` [Bug c++/102535] " ppalka at gcc dot gnu.org
` (5 more replies)
0 siblings, 6 replies; 7+ messages in thread
From: de34 at live dot cn @ 2021-09-30 2:45 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102535
Bug ID: 102535
Summary: __is_trivially_constructible rejects some trivial
cases in aggregate initializations
Product: gcc
Version: 10.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: de34 at live dot cn
Target Milestone: ---
It seems that gcc's __is_trivially_constructible (the underlying mechanism of
std::is_trivially_constructible in libstdc++) gives inconsistent answers to
whether aggregate initializations performed by direct-non-list-initializations
(available since C++20) affect triviality of operations.
#include <type_traits>
#include <iostream>
struct A { int x; };
struct B { float y; };
struct C { A a; B b; };
int main()
{
#if __cpp_aggregate_paren_init >= 201902L
std::cout
<< std::is_constructible_v<C, A> << '\n' // 1
<< std::is_constructible_v<C, A, B> << '\n' // 1
<< !std::is_constructible_v<C, B> << '\n' // 1
<< std::is_trivially_constructible_v<C, A> << '\n' // 1
<< std::is_trivially_constructible_v<C, A, B> << '\n'; // 0, seems
buggy
#endif
}
According to the definitions, initialization of a C variable from A or A and B
(both treated as xvalues according to [meta.unary.prop]/8) only calls trivial
move constructors. It seems unreasonable that
std::is_trivially_constructible_v<C, A> is true but
std::is_trivially_constructible_v<C, A, B> is false, they should be both true
in C++20.
This bug has been existing since gcc 10.1.0, and is not fixed in 12.0.0
20210721:
https://wandbox.org/permlink/L0ZLipQZLsCOqYcT
https://wandbox.org/permlink/lBwowJpeFshRC03z
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/102535] __is_trivially_constructible rejects some trivial cases in aggregate initializations
2021-09-30 2:45 [Bug c++/102535] New: __is_trivially_constructible rejects some trivial cases in aggregate initializations de34 at live dot cn
@ 2021-09-30 14:59 ` ppalka at gcc dot gnu.org
2021-09-30 21:51 ` cvs-commit at gcc dot gnu.org
` (4 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: ppalka at gcc dot gnu.org @ 2021-09-30 14:59 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102535
Patrick Palka <ppalka at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Last reconfirmed| |2021-09-30
Assignee|unassigned at gcc dot gnu.org |ppalka at gcc dot gnu.org
CC| |ppalka at gcc dot gnu.org
Status|UNCONFIRMED |ASSIGNED
--- Comment #1 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Confirmed.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/102535] __is_trivially_constructible rejects some trivial cases in aggregate initializations
2021-09-30 2:45 [Bug c++/102535] New: __is_trivially_constructible rejects some trivial cases in aggregate initializations de34 at live dot cn
2021-09-30 14:59 ` [Bug c++/102535] " ppalka at gcc dot gnu.org
@ 2021-09-30 21:51 ` cvs-commit at gcc dot gnu.org
2021-10-05 8:36 ` cvs-commit at gcc dot gnu.org
` (3 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2021-09-30 21:51 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102535
--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Patrick Palka <ppalka@gcc.gnu.org>:
https://gcc.gnu.org/g:9845c52db38f15740861435f38f7e5ad8a8de2ec
commit r12-3997-g9845c52db38f15740861435f38f7e5ad8a8de2ec
Author: Patrick Palka <ppalka@redhat.com>
Date: Thu Sep 30 17:34:23 2021 -0400
c++: __is_trivially_xible and multi-arg aggr paren init [PR102535]
is_xible_helper assumes only 0- and 1-argument ctors can be trivial, but
C++20 aggregate paren init means multi-arg ctors can now be trivial too.
This patch relaxes the relevant early exit check accordingly.
PR c++/102535
gcc/cp/ChangeLog:
* method.c (is_xible_helper): Don't exit early for multi-arg
ctors in C++20.
gcc/testsuite/ChangeLog:
* g++.dg/ext/is_trivially_constructible7.C: New test.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/102535] __is_trivially_constructible rejects some trivial cases in aggregate initializations
2021-09-30 2:45 [Bug c++/102535] New: __is_trivially_constructible rejects some trivial cases in aggregate initializations de34 at live dot cn
2021-09-30 14:59 ` [Bug c++/102535] " ppalka at gcc dot gnu.org
2021-09-30 21:51 ` cvs-commit at gcc dot gnu.org
@ 2021-10-05 8:36 ` cvs-commit at gcc dot gnu.org
2021-10-06 14:15 ` cvs-commit at gcc dot gnu.org
` (2 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2021-10-05 8:36 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102535
--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jonathan Wakely <redi@gcc.gnu.org>:
https://gcc.gnu.org/g:7646847df71e57edca5ec5b8c3c3dc4550dcb49d
commit r12-4181-g7646847df71e57edca5ec5b8c3c3dc4550dcb49d
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Tue Oct 5 09:32:11 2021 +0100
libstdc++: Fix testcase for newly-implemented C++20 semantics [PR102535]
libstdc++-v3/ChangeLog:
PR c++/102535
* testsuite/20_util/is_trivially_constructible/value.cc: Adjust
expected value for C++20.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/102535] __is_trivially_constructible rejects some trivial cases in aggregate initializations
2021-09-30 2:45 [Bug c++/102535] New: __is_trivially_constructible rejects some trivial cases in aggregate initializations de34 at live dot cn
` (2 preceding siblings ...)
2021-10-05 8:36 ` cvs-commit at gcc dot gnu.org
@ 2021-10-06 14:15 ` cvs-commit at gcc dot gnu.org
2021-10-12 11:00 ` cvs-commit at gcc dot gnu.org
2021-10-12 13:33 ` ppalka at gcc dot gnu.org
5 siblings, 0 replies; 7+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2021-10-06 14:15 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102535
--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Patrick Palka
<ppalka@gcc.gnu.org>:
https://gcc.gnu.org/g:d80c0e4584acc204ca9a2f8880ad455fef48371f
commit r11-9085-gd80c0e4584acc204ca9a2f8880ad455fef48371f
Author: Patrick Palka <ppalka@redhat.com>
Date: Thu Sep 30 17:54:17 2021 -0400
c++: __is_trivially_xible and multi-arg aggr paren init [PR102535]
is_xible_helper assumes only 0- and 1-argument ctors can be trivial, but
C++20 aggregate paren init means multi-arg ctors can now be trivial too.
This patch relaxes the relevant early exit check accordingly.
PR c++/102535
gcc/cp/ChangeLog:
* method.c (is_xible_helper): Don't exit early for multi-arg
ctors in C++20.
gcc/testsuite/ChangeLog:
* g++.dg/ext/is_trivially_constructible7.C: New test.
(cherry picked from commit 9845c52db38f15740861435f38f7e5ad8a8de2ec)
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/102535] __is_trivially_constructible rejects some trivial cases in aggregate initializations
2021-09-30 2:45 [Bug c++/102535] New: __is_trivially_constructible rejects some trivial cases in aggregate initializations de34 at live dot cn
` (3 preceding siblings ...)
2021-10-06 14:15 ` cvs-commit at gcc dot gnu.org
@ 2021-10-12 11:00 ` cvs-commit at gcc dot gnu.org
2021-10-12 13:33 ` ppalka at gcc dot gnu.org
5 siblings, 0 replies; 7+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2021-10-12 11:00 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102535
--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Jonathan Wakely
<redi@gcc.gnu.org>:
https://gcc.gnu.org/g:7b4e6d75b18dbb52bf507dbfd4c8e694e476d2af
commit r11-9120-g7b4e6d75b18dbb52bf507dbfd4c8e694e476d2af
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Tue Oct 5 09:32:11 2021 +0100
libstdc++: Fix testcase for newly-implemented C++20 semantics [PR102535]
libstdc++-v3/ChangeLog:
PR c++/102535
* testsuite/20_util/is_trivially_constructible/value.cc: Adjust
expected value for C++20.
(cherry picked from commit 7646847df71e57edca5ec5b8c3c3dc4550dcb49d)
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/102535] __is_trivially_constructible rejects some trivial cases in aggregate initializations
2021-09-30 2:45 [Bug c++/102535] New: __is_trivially_constructible rejects some trivial cases in aggregate initializations de34 at live dot cn
` (4 preceding siblings ...)
2021-10-12 11:00 ` cvs-commit at gcc dot gnu.org
@ 2021-10-12 13:33 ` ppalka at gcc dot gnu.org
5 siblings, 0 replies; 7+ messages in thread
From: ppalka at gcc dot gnu.org @ 2021-10-12 13:33 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102535
Patrick Palka <ppalka at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Target Milestone|--- |11.3
Status|ASSIGNED |RESOLVED
--- Comment #6 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Fixed for GCC 11.3/12
^ permalink raw reply [flat|nested] 7+ messages in thread
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