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* [Bug middle-end/110764] New: [12/13/14 Regression] False positive -Warray-bounds warning swapping std::thread::id
@ 2023-07-21 10:43 redi at gcc dot gnu.org
2023-07-21 21:19 ` [Bug middle-end/110764] " pinskia at gcc dot gnu.org
` (10 more replies)
0 siblings, 11 replies; 12+ messages in thread
From: redi at gcc dot gnu.org @ 2023-07-21 10:43 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110764
Bug ID: 110764
Summary: [12/13/14 Regression] False positive -Warray-bounds
warning swapping std::thread::id
Product: gcc
Version: 12.3.1
Status: UNCONFIRMED
Keywords: diagnostic
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: redi at gcc dot gnu.org
Target Milestone: ---
#include <iostream>
#include <thread>
#include <vector>
void g(int n);
void g(int n) {
std::cout << "consume: " << n << std::endl;
}
int main(void) {
std::vector<std::thread> threads(1);
// The compiler error comes from the two threads below.
threads[0] = std::thread(g, 42);
threads[1] = std::thread(g, 42);
threads[0].join();
threads[1].join();
return (0);
}
Compiled with -Warray-bounds -O2 this gives a false positive:
In file included from
/home/jwakely/gcc/12.1.0/include/c++/12.1.0/bits/exception_ptr.h:43,
from
/home/jwakely/gcc/12.1.0/include/c++/12.1.0/exception:168,
from /home/jwakely/gcc/12.1.0/include/c++/12.1.0/ios:39,
from /home/jwakely/gcc/12.1.0/include/c++/12.1.0/ostream:38,
from /home/jwakely/gcc/12.1.0/include/c++/12.1.0/iostream:39,
from max.cc:1:
In function ‘std::_Require<std::__not_<std::__is_tuple_like<_Tp> >,
std::is_move_constructible<_Tp>, std::is_move_assignable<_Tp> > std::swap(_Tp&,
_Tp&) [with _Tp = thread::id]’,
inlined from ‘void std::thread::swap(std::thread&)’ at
/home/jwakely/gcc/12.1.0/include/c++/12.1.0/bits/std_thread.h:171:16,
inlined from ‘std::thread& std::thread::operator=(std::thread&&)’ at
/home/jwakely/gcc/12.1.0/include/c++/12.1.0/bits/std_thread.h:165:11,
inlined from ‘int main()’ at max.cc:15:35:
/home/jwakely/gcc/12.1.0/include/c++/12.1.0/bits/move.h:205:7: warning: array
subscript 1 is outside array bounds of ‘std::thread [1]’ [-Warray-bounds]
205 | __a = _GLIBCXX_MOVE(__b);
| ^~~
In file included from
/home/jwakely/gcc/12.1.0/include/c++/12.1.0/x86_64-pc-linux-gnu/bits/c++allocator.h:33,
from
/home/jwakely/gcc/12.1.0/include/c++/12.1.0/bits/allocator.h:46,
from /home/jwakely/gcc/12.1.0/include/c++/12.1.0/string:41,
from
/home/jwakely/gcc/12.1.0/include/c++/12.1.0/bits/locale_classes.h:40,
from
/home/jwakely/gcc/12.1.0/include/c++/12.1.0/bits/ios_base.h:41,
from /home/jwakely/gcc/12.1.0/include/c++/12.1.0/ios:42:
In member function ‘_Tp* std::__new_allocator<_Tp>::allocate(size_type, const
void*) [with _Tp = std::thread]’,
inlined from ‘static _Tp* std::allocator_traits<std::allocator<_CharT>
>::allocate(allocator_type&, size_type) [with _Tp = std::thread]’ at
/home/jwakely/gcc/12.1.0/include/c++/12.1.0/bits/alloc_traits.h:464:28,
inlined from ‘std::_Vector_base<_Tp, _Alloc>::pointer
std::_Vector_base<_Tp, _Alloc>::_M_allocate(std::size_t) [with _Tp =
std::thread; _Alloc = std::allocator<std::thread>]’ at
/home/jwakely/gcc/12.1.0/include/c++/12.1.0/bits/stl_vector.h:378:33,
inlined from ‘void std::_Vector_base<_Tp,
_Alloc>::_M_create_storage(std::size_t) [with _Tp = std::thread; _Alloc =
std::allocator<std::thread>]’ at
/home/jwakely/gcc/12.1.0/include/c++/12.1.0/bits/stl_vector.h:395:44,
inlined from ‘std::_Vector_base<_Tp, _Alloc>::_Vector_base(std::size_t,
const allocator_type&) [with _Tp = std::thread; _Alloc =
std::allocator<std::thread>]’ at
/home/jwakely/gcc/12.1.0/include/c++/12.1.0/bits/stl_vector.h:332:26,
inlined from ‘std::vector<_Tp, _Alloc>::vector(size_type, const
allocator_type&) [with _Tp = std::thread; _Alloc =
std::allocator<std::thread>]’ at
/home/jwakely/gcc/12.1.0/include/c++/12.1.0/bits/stl_vector.h:552:47,
inlined from ‘int main()’ at max.cc:12:39:
/home/jwakely/gcc/12.1.0/include/c++/12.1.0/bits/new_allocator.h:137:55: note:
at offset 8 into object of size 8 allocated by ‘operator new’
137 | return static_cast<_Tp*>(_GLIBCXX_OPERATOR_NEW(__n *
sizeof(_Tp)));
| ^
This started with r12-1992
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug middle-end/110764] [12/13/14 Regression] False positive -Warray-bounds warning swapping std::thread::id
2023-07-21 10:43 [Bug middle-end/110764] New: [12/13/14 Regression] False positive -Warray-bounds warning swapping std::thread::id redi at gcc dot gnu.org
@ 2023-07-21 21:19 ` pinskia at gcc dot gnu.org
2023-07-21 21:21 ` pinskia at gcc dot gnu.org
` (9 subsequent siblings)
10 siblings, 0 replies; 12+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-07-21 21:19 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110764
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
hmm, this code seems like undefined code. If I change 1 to 2 as you are
accessing 2 elements via operator[], there is no warning ...
The warning seems correct and even says 1 bounds is above the array bounds of
[1].
The location of the warning seems off but I don't think the warning in this
case is false positive though.
Maybe it is due to the reduced testcase though.
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug middle-end/110764] [12/13/14 Regression] False positive -Warray-bounds warning swapping std::thread::id
2023-07-21 10:43 [Bug middle-end/110764] New: [12/13/14 Regression] False positive -Warray-bounds warning swapping std::thread::id redi at gcc dot gnu.org
2023-07-21 21:19 ` [Bug middle-end/110764] " pinskia at gcc dot gnu.org
@ 2023-07-21 21:21 ` pinskia at gcc dot gnu.org
2023-07-21 22:07 ` maxim.yegorushkin at gmail dot com
` (8 subsequent siblings)
10 siblings, 0 replies; 12+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-07-21 21:21 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110764
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
So reading the original bug report, it is almost definitely an incorrectly
reduced testcase.
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug middle-end/110764] [12/13/14 Regression] False positive -Warray-bounds warning swapping std::thread::id
2023-07-21 10:43 [Bug middle-end/110764] New: [12/13/14 Regression] False positive -Warray-bounds warning swapping std::thread::id redi at gcc dot gnu.org
2023-07-21 21:19 ` [Bug middle-end/110764] " pinskia at gcc dot gnu.org
2023-07-21 21:21 ` pinskia at gcc dot gnu.org
@ 2023-07-21 22:07 ` maxim.yegorushkin at gmail dot com
2023-07-21 22:11 ` maxim.yegorushkin at gmail dot com
` (7 subsequent siblings)
10 siblings, 0 replies; 12+ messages in thread
From: maxim.yegorushkin at gmail dot com @ 2023-07-21 22:07 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110764
Maxim Egorushkin <maxim.yegorushkin at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |maxim.yegorushkin at gmail dot com
--- Comment #3 from Maxim Egorushkin <maxim.yegorushkin at gmail dot com> ---
The original correct reproduction:
#include <thread>
#include <vector>
void g(int);
void f() {
std::vector<std::thread> threads(1);
threads[0] = std::thread(g, 42); // Compiler error comes from this
statement.
threads[0].join();
}
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug middle-end/110764] [12/13/14 Regression] False positive -Warray-bounds warning swapping std::thread::id
2023-07-21 10:43 [Bug middle-end/110764] New: [12/13/14 Regression] False positive -Warray-bounds warning swapping std::thread::id redi at gcc dot gnu.org
` (2 preceding siblings ...)
2023-07-21 22:07 ` maxim.yegorushkin at gmail dot com
@ 2023-07-21 22:11 ` maxim.yegorushkin at gmail dot com
2023-07-21 22:25 ` pinskia at gcc dot gnu.org
` (6 subsequent siblings)
10 siblings, 0 replies; 12+ messages in thread
From: maxim.yegorushkin at gmail dot com @ 2023-07-21 22:11 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110764
--- Comment #4 from Maxim Egorushkin <maxim.yegorushkin at gmail dot com> ---
Full context: https://github.com/max0x7ba/atomic_queue/issues/55
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug middle-end/110764] [12/13/14 Regression] False positive -Warray-bounds warning swapping std::thread::id
2023-07-21 10:43 [Bug middle-end/110764] New: [12/13/14 Regression] False positive -Warray-bounds warning swapping std::thread::id redi at gcc dot gnu.org
` (3 preceding siblings ...)
2023-07-21 22:11 ` maxim.yegorushkin at gmail dot com
@ 2023-07-21 22:25 ` pinskia at gcc dot gnu.org
2023-07-21 22:34 ` maxim.yegorushkin at gmail dot com
` (5 subsequent siblings)
10 siblings, 0 replies; 12+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-07-21 22:25 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110764
--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Maxim Egorushkin from comment #3)
> The original correct reproduction:
>
> #include <thread>
> #include <vector>
>
> void g(int);
>
> void f() {
> std::vector<std::thread> threads(1);
> threads[0] = std::thread(g, 42); // Compiler error comes from this
> statement.
> threads[0].join();
> }
Can you provide the preprocessed source? Since I can't seem to reproduce it
with the above.
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug middle-end/110764] [12/13/14 Regression] False positive -Warray-bounds warning swapping std::thread::id
2023-07-21 10:43 [Bug middle-end/110764] New: [12/13/14 Regression] False positive -Warray-bounds warning swapping std::thread::id redi at gcc dot gnu.org
` (4 preceding siblings ...)
2023-07-21 22:25 ` pinskia at gcc dot gnu.org
@ 2023-07-21 22:34 ` maxim.yegorushkin at gmail dot com
2023-07-21 22:35 ` maxim.yegorushkin at gmail dot com
` (4 subsequent siblings)
10 siblings, 0 replies; 12+ messages in thread
From: maxim.yegorushkin at gmail dot com @ 2023-07-21 22:34 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110764
--- Comment #6 from Maxim Egorushkin <maxim.yegorushkin at gmail dot com> ---
> Can you provide the preprocessed source? Since I can't seem to reproduce it with the above.
It should be compiled with "-pthread -std=gnu++14 -O3 -Wall -Wextra -Werror" to
trigger the warning/error.
But I don't have access to Debian gcc-13, which is the origin of this issue, to
be able to provide a preprocessed source.
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug middle-end/110764] [12/13/14 Regression] False positive -Warray-bounds warning swapping std::thread::id
2023-07-21 10:43 [Bug middle-end/110764] New: [12/13/14 Regression] False positive -Warray-bounds warning swapping std::thread::id redi at gcc dot gnu.org
` (5 preceding siblings ...)
2023-07-21 22:34 ` maxim.yegorushkin at gmail dot com
@ 2023-07-21 22:35 ` maxim.yegorushkin at gmail dot com
2023-07-21 22:38 ` maxim.yegorushkin at gmail dot com
` (3 subsequent siblings)
10 siblings, 0 replies; 12+ messages in thread
From: maxim.yegorushkin at gmail dot com @ 2023-07-21 22:35 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110764
--- Comment #7 from Maxim Egorushkin <maxim.yegorushkin at gmail dot com> ---
> Can you provide the preprocessed source? Since I can't seem to reproduce it with the above.
It should be compiled with "-pthread -std=gnu++14 -O3 -Wall -Wextra -Werror" to
trigger the warning/error.
But I don't have access to Debian gcc-13, which is the origin of this issue, to
be able to provide a preprocessed source.
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug middle-end/110764] [12/13/14 Regression] False positive -Warray-bounds warning swapping std::thread::id
2023-07-21 10:43 [Bug middle-end/110764] New: [12/13/14 Regression] False positive -Warray-bounds warning swapping std::thread::id redi at gcc dot gnu.org
` (6 preceding siblings ...)
2023-07-21 22:35 ` maxim.yegorushkin at gmail dot com
@ 2023-07-21 22:38 ` maxim.yegorushkin at gmail dot com
2023-07-21 23:08 ` redi at gcc dot gnu.org
` (2 subsequent siblings)
10 siblings, 0 replies; 12+ messages in thread
From: maxim.yegorushkin at gmail dot com @ 2023-07-21 22:38 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110764
--- Comment #8 from Maxim Egorushkin <maxim.yegorushkin at gmail dot com> ---
It was supposed to be one comment, but I kept clicking "save changes" button
because it provided no visual feedback that the comment was being posted.
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug middle-end/110764] [12/13/14 Regression] False positive -Warray-bounds warning swapping std::thread::id
2023-07-21 10:43 [Bug middle-end/110764] New: [12/13/14 Regression] False positive -Warray-bounds warning swapping std::thread::id redi at gcc dot gnu.org
` (7 preceding siblings ...)
2023-07-21 22:38 ` maxim.yegorushkin at gmail dot com
@ 2023-07-21 23:08 ` redi at gcc dot gnu.org
2023-10-17 10:27 ` rguenth at gcc dot gnu.org
2024-03-07 23:28 ` law at gcc dot gnu.org
10 siblings, 0 replies; 12+ messages in thread
From: redi at gcc dot gnu.org @ 2023-07-21 23:08 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110764
--- Comment #9 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #2)
> So reading the original bug report, it is almost definitely an incorrectly
> reduced testcase.
Oops, yes, sorry for not noticing that before filling the bug
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug middle-end/110764] [12/13/14 Regression] False positive -Warray-bounds warning swapping std::thread::id
2023-07-21 10:43 [Bug middle-end/110764] New: [12/13/14 Regression] False positive -Warray-bounds warning swapping std::thread::id redi at gcc dot gnu.org
` (8 preceding siblings ...)
2023-07-21 23:08 ` redi at gcc dot gnu.org
@ 2023-10-17 10:27 ` rguenth at gcc dot gnu.org
2024-03-07 23:28 ` law at gcc dot gnu.org
10 siblings, 0 replies; 12+ messages in thread
From: rguenth at gcc dot gnu.org @ 2023-10-17 10:27 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110764
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |12.4
^ permalink raw reply [flat|nested] 12+ messages in thread
* [Bug middle-end/110764] [12/13/14 Regression] False positive -Warray-bounds warning swapping std::thread::id
2023-07-21 10:43 [Bug middle-end/110764] New: [12/13/14 Regression] False positive -Warray-bounds warning swapping std::thread::id redi at gcc dot gnu.org
` (9 preceding siblings ...)
2023-10-17 10:27 ` rguenth at gcc dot gnu.org
@ 2024-03-07 23:28 ` law at gcc dot gnu.org
10 siblings, 0 replies; 12+ messages in thread
From: law at gcc dot gnu.org @ 2024-03-07 23:28 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110764
Jeffrey A. Law <law at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |law at gcc dot gnu.org
Priority|P3 |P2
^ permalink raw reply [flat|nested] 12+ messages in thread
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