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* [Bug c++/95656] New: Inconsistent output in compiling an undefined function
@ 2020-06-12 14:13 haoxintu at gmail dot com
2020-06-12 14:21 ` [Bug c++/95656] " jakub at gcc dot gnu.org
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: haoxintu at gmail dot com @ 2020-06-12 14:13 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95656
Bug ID: 95656
Summary: Inconsistent output in compiling an undefined function
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: haoxintu at gmail dot com
Target Milestone: ---
This code bug.cc
#include<iostream>
int main(){
int a ();
std::cout << a << std::endl;
return 0;
}
In GCC-trunk without "-fsanitize=undefined"
$g++ bug.cc ; ./a.out
1
$g++-trunk -fsanitize=undefined bug.cc
/tmp/ccm15L4R.o: In function `main':
bug.cc:(.text+0x8f): undefined reference to `a()'
collect2: error: ld returned 1 exit status
While in GCC-5
$g++-5 bug.cc ; ./a.out
1
$g++-5 -fsanitize=undefined bug.cc ; ./a.out
1
My GCC versions are
$g++-trunk --version
g++ (GCC) 11.0.0 20200526 (experimental)
Copyright (C) 2020 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
$g++-5 --version
g++-5 (Ubuntu 5.5.0-12ubuntu6~18.04) 5.5.0 20171010
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
I also tested bug.cc in clang, it compiles well and output "1" whether adding
"-fsanitize=undefined" or not.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/95656] Inconsistent output in compiling an undefined function
2020-06-12 14:13 [Bug c++/95656] New: Inconsistent output in compiling an undefined function haoxintu at gmail dot com
@ 2020-06-12 14:21 ` jakub at gcc dot gnu.org
2020-06-14 20:21 ` pinskia at gcc dot gnu.org
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: jakub at gcc dot gnu.org @ 2020-06-12 14:21 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95656
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jakub at gcc dot gnu.org
--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
I don't see anything wrong on that.
You end up with essentially a != nullptr test, which is in some cases optimized
away, but during sanitization tests whether some address is non-NULL are
intentionally not optimized in case they would end up being NULL
(-fsanitize=undefined implies -fno-delete-null-pointer-checks).
You get the same result if you use -fno-delete-null-pointer-checks without
sanitization.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/95656] Inconsistent output in compiling an undefined function
2020-06-12 14:13 [Bug c++/95656] New: Inconsistent output in compiling an undefined function haoxintu at gmail dot com
2020-06-12 14:21 ` [Bug c++/95656] " jakub at gcc dot gnu.org
@ 2020-06-14 20:21 ` pinskia at gcc dot gnu.org
2023-12-10 23:47 ` pinskia at gcc dot gnu.org
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu.org @ 2020-06-14 20:21 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95656
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |INVALID
Status|UNCONFIRMED |RESOLVED
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
As mentioned invalid.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/95656] Inconsistent output in compiling an undefined function
2020-06-12 14:13 [Bug c++/95656] New: Inconsistent output in compiling an undefined function haoxintu at gmail dot com
2020-06-12 14:21 ` [Bug c++/95656] " jakub at gcc dot gnu.org
2020-06-14 20:21 ` pinskia at gcc dot gnu.org
@ 2023-12-10 23:47 ` pinskia at gcc dot gnu.org
2023-12-10 23:48 ` pinskia at gcc dot gnu.org
2023-12-10 23:49 ` pinskia at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-12-10 23:47 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95656
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |resence at parsoma dot net
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 112947 has been marked as a duplicate of this bug. ***
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/95656] Inconsistent output in compiling an undefined function
2020-06-12 14:13 [Bug c++/95656] New: Inconsistent output in compiling an undefined function haoxintu at gmail dot com
` (2 preceding siblings ...)
2023-12-10 23:47 ` pinskia at gcc dot gnu.org
@ 2023-12-10 23:48 ` pinskia at gcc dot gnu.org
2023-12-10 23:49 ` pinskia at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-12-10 23:48 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95656
--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
* See also PR79265 and PR98109
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/95656] Inconsistent output in compiling an undefined function
2020-06-12 14:13 [Bug c++/95656] New: Inconsistent output in compiling an undefined function haoxintu at gmail dot com
` (3 preceding siblings ...)
2023-12-10 23:48 ` pinskia at gcc dot gnu.org
@ 2023-12-10 23:49 ` pinskia at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-12-10 23:49 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95656
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
See Also| |https://gcc.gnu.org/bugzill
| |a/show_bug.cgi?id=101576
--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
And see PR 101576 too.
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2023-12-10 23:49 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2020-06-12 14:13 [Bug c++/95656] New: Inconsistent output in compiling an undefined function haoxintu at gmail dot com
2020-06-12 14:21 ` [Bug c++/95656] " jakub at gcc dot gnu.org
2020-06-14 20:21 ` pinskia at gcc dot gnu.org
2023-12-10 23:47 ` pinskia at gcc dot gnu.org
2023-12-10 23:48 ` pinskia at gcc dot gnu.org
2023-12-10 23:49 ` pinskia at gcc dot gnu.org
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