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From: "msebor at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/98465] Bogus warning stringop-overread wuth -std=gnu++20 -O2 and std::string::insert Date: Wed, 06 Jan 2021 22:38:02 +0000 [thread overview] Message-ID: <bug-98465-4-P2tFx4hWfT@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-98465-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98465 --- Comment #5 from Martin Sebor <msebor at gcc dot gnu.org> --- Comparing the code emitted by GCC 10 and the current trunk shows that the former doesn't inline std::string::replace() regardless of the inlining limit. The translation unit obtained with the former shows declarations of explicit instantiations of basic_string: $ g++-10 -O2 -E -Wall -g t.C | grep template | grep basic_string template<typename, typename, typename> friend class basic_stringbuf; extern template class basic_string<char>; extern template class basic_string<wchar_t>; Current trunk doesn't declare them which is what allows std::string::replace to be inlined. Removing the declaration of the explicit instantiation from the translation unit lets GCC 10 inline string::replace but the warning is not issued because the location of the call is in a system header. But enabling warning for those via -Wsystem-headers shows the warning even with GCC 10: $ g++-10 -E pr98465.C | sed "/extern template class basic_string/d" > pr98465.ii && g++-10 -O2 -S -Wall -Wsystem-headers pr98465.ii In file included from /build/gcc-10-branch/x86_64-pc-linux-gnu/libstdc++-v3/include/string:56, from pr98465.C:1: /build/gcc-10-branch/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/basic_string.tcc: In function ‘void f(std::string&)’: /build/gcc-10-branch/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/basic_string.tcc:456:20: warning: offset ‘2’ outside bounds of constant string [-Warray-bounds] 456 | this->_S_copy(__p, __s + __len2 - __len1, __len2); | ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ pr98465.C:3:12: note: ‘constantString’ declared here 3 | const char constantString[] = {42, 53}; | ^~~~~~~~~~~~~~ In file included from /build/gcc-10-branch/x86_64-pc-linux-gnu/libstdc++-v3/include/string:40, from pr98465.C:1: In static member function ‘static std::char_traits<char>::char_type* std::char_traits<char>::copy(std::char_traits<char>::char_type*, const char_type*, std::size_t)’, inlined from ‘void f(std::string&)’ at /build/gcc-10-branch/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/basic_string.h:351:21: /build/gcc-10-branch/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/char_traits.h:395:49: warning: ‘void* __builtin_memcpy(void*, const void*, long unsigned int)’ reading 2 bytes from a region of size 0 [-Wstringop-overflow=] 395 | return static_cast<char_type*>(__builtin_memcpy(__s1, __s2, __n)); | ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~
next prev parent reply other threads:[~2021-01-06 22:38 UTC|newest] Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-12-28 18:36 [Bug middle-end/98465] New: " romain.geissler at amadeus dot com 2020-12-28 20:54 ` [Bug middle-end/98465] " msebor at gcc dot gnu.org 2020-12-30 12:49 ` romain.geissler at amadeus dot com 2020-12-30 13:22 ` romain.geissler at amadeus dot com 2020-12-30 21:25 ` msebor at gcc dot gnu.org 2021-01-06 22:38 ` msebor at gcc dot gnu.org [this message] 2021-01-06 22:59 ` msebor at gcc dot gnu.org 2021-01-06 23:14 ` msebor at gcc dot gnu.org 2021-01-07 20:26 ` msebor at gcc dot gnu.org 2021-01-13 18:19 ` msebor at gcc dot gnu.org 2021-01-13 18:41 ` law at redhat dot com 2021-01-13 18:52 ` jakub at gcc dot gnu.org 2021-01-13 19:02 ` msebor at gcc dot gnu.org 2021-01-13 19:14 ` jakub at gcc dot gnu.org 2021-01-13 19:30 ` msebor at gcc dot gnu.org 2021-01-14 2:21 ` msebor at gcc dot gnu.org 2021-01-19 19:00 ` msebor at gcc dot gnu.org 2021-01-20 23:20 ` [Bug middle-end/98465] [11 Regression] Bogus -Wstringop-overread with " msebor at gcc dot gnu.org 2021-02-04 14:03 ` jakub at gcc dot gnu.org 2021-02-04 14:39 ` redi at gcc dot gnu.org 2021-02-04 15:25 ` jakub at gcc dot gnu.org 2021-02-04 15:53 ` redi at gcc dot gnu.org 2021-02-04 15:54 ` redi at gcc dot gnu.org 2021-02-04 16:02 ` msebor at gcc dot gnu.org 2021-02-04 16:58 ` jakub at gcc dot gnu.org 2021-02-04 17:12 ` jakub at gcc dot gnu.org 2021-02-04 20:57 ` msebor at gcc dot gnu.org 2021-02-04 21:09 ` jakub at gcc dot gnu.org 2021-02-05 10:15 ` jakub at gcc dot gnu.org 2021-02-08 18:51 ` jakub at gcc dot gnu.org 2021-02-09 11:33 ` cvs-commit at gcc dot gnu.org 2021-02-09 11:35 ` [Bug middle-end/98465] " jakub at gcc dot gnu.org 2021-02-19 23:41 ` msebor at gcc dot gnu.org 2021-11-12 19:53 ` msebor at gcc dot gnu.org 2022-02-15 3:55 ` Randy at miningrigrentals dot com 2022-02-15 9:47 ` redi at gcc dot gnu.org 2022-02-15 9:55 ` Randy at miningrigrentals dot com 2022-02-15 10:02 ` redi at gcc dot gnu.org 2022-02-15 10:50 ` Randy at miningrigrentals dot com 2022-02-15 12:29 ` redi at gcc dot gnu.org 2022-02-15 12:40 ` Randy at miningrigrentals dot com 2022-02-15 12:52 ` redi at gcc dot gnu.org 2022-02-15 19:23 ` Randy at miningrigrentals dot com 2022-02-17 10:37 ` redi at gcc dot gnu.org
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