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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) -- links below jump to the message on this page -- 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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