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From: "msebor at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug libstdc++/54924] Warn for std::string constructor with wrong size Date: Wed, 15 Dec 2021 17:58:25 +0000 [thread overview] Message-ID: <bug-54924-4-z2pK8LGvmo@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-54924-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54924 Martin Sebor <msebor at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Resolution|--- |FIXED Status|ASSIGNED |RESOLVED --- Comment #15 from Martin Sebor <msebor at gcc dot gnu.org> --- GCC 11 and 12 finally diagnose this problem even without -Wsystem-headers, albeit inconsistently. At -O1 GCC 11 issues -Wstringop-overread: In file included from /build/gcc-11-branch/x86_64-pc-linux-gnu/libstdc++-v3/include/string:40, from pr54924.C:2: 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 ‘static void std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_S_copy(_CharT*, const _CharT*, std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /build/gcc-11-branch/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/basic_string.h:359:21, inlined from ‘static void std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_S_copy_chars(_CharT*, const _CharT*, const _CharT*) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /build/gcc-11-branch/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/basic_string.h:406:16, inlined from ‘void std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_M_construct(_InIterator, _InIterator, std::forward_iterator_tag) [with _FwdIterator = const char*; _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /build/gcc-11-branch/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/basic_string.tcc:225:25, inlined from ‘void std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_M_construct_aux(_InIterator, _InIterator, std::__false_type) [with _InIterator = const char*; _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /build/gcc-11-branch/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/basic_string.h:255:23, inlined from ‘void std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_M_construct(_InIterator, _InIterator) [with _InIterator = const char*; _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /build/gcc-11-branch/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/basic_string.h:274:20, inlined from ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::basic_string(const _CharT*, std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type, const _Alloc&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /build/gcc-11-branch/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/basic_string.h:521:21, inlined from ‘void __static_initialization_and_destruction_0(int, int)’ at pr54924.C:4:24, inlined from ‘(static initializers for pr54924.C)’ at pr54924.C:4:25: /build/gcc-11-branch/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/char_traits.h:409:56: warning: ‘void* __builtin_memcpy(void*, const void*, long unsigned int)’ reading 5 bytes from a region of size 4 [-Wstringop-overread] 409 | return static_cast<char_type*>(__builtin_memcpy(__s1, __s2, __n)); | ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~ As a result of g:b8f2efaed02e8b03d215d74e42d3707761772f64 GCC 12 doesn't issue -Wstringop-overread at any level but at -O2 it does issue -Warray-bounds: In file included from /build/gcc-master/x86_64-pc-linux-gnu/libstdc++-v3/include/string:53, from pr54924.C:2: In constructor ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::basic_string(const _CharT*, size_type, const _Alloc&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’, inlined from ‘void __static_initialization_and_destruction_0(int, int)’ at pr54924.C:4:24, inlined from ‘(static initializers for pr54924.C)’ at pr54924.C:4:25: /build/gcc-master/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/basic_string.h:620:21: warning: array subscript 5 is outside array bounds of ‘const char [4]’ [-Warray-bounds] 620 | _M_construct(__s, __s + __n, std::forward_iterator_tag()); | ~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I'm not happy with how this has turned out but I'm also not sure how to improve things, so I'll resolve this as fixed.
next prev parent reply other threads:[~2021-12-15 17:58 UTC|newest] Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-10-14 17:06 [Bug c++/54924] New: " david at doublewise dot net 2012-10-14 17:44 ` [Bug libstdc++/54924] " redi at gcc dot gnu.org 2012-10-14 18:40 ` david at doublewise dot net 2021-12-15 17:58 ` msebor at gcc dot gnu.org [this message] 2021-12-15 21:30 ` redi at gcc dot gnu.org
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