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* [Bug tree-optimization/104336] New: bogus -Wrestrict for std::string assignment with
@ 2022-02-01 21:24 msebor at gcc dot gnu.org
  2022-02-01 21:25 ` [Bug tree-optimization/104336] " msebor at gcc dot gnu.org
                   ` (3 more replies)
  0 siblings, 4 replies; 5+ messages in thread
From: msebor at gcc dot gnu.org @ 2022-02-01 21:24 UTC (permalink / raw)
  To: gcc-bugs

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104336

            Bug ID: 104336
           Summary: bogus -Wrestrict for std::string assignment with
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: msebor at gcc dot gnu.org
  Target Milestone: ---

The following false positive was reported in
https://bugzilla.redhat.com/show_bug.cgi?id=2047428.  It boils down to the same
underlying problem as in pr98465.

$ cat t.C && g++ -O2 -S -Wall -D_GLIBCXX_ASSERTIONS t.C
#include <string>

std::string s;

void f (void)
{
  s = "/";
}

In file included from
/build/gcc-master/x86_64-pc-linux-gnu/libstdc++-v3/include/string:40,
                 from ../t.C:1:
In static member function ‘static std::char_traits<char>::char_type*
std::char_traits<char>::copy(char_type*, const char_type*, std::size_t)’,
    inlined from ‘static void std::__cxx11::basic_string<_CharT, _Traits,
_Alloc>::_S_copy(_CharT*, const _CharT*, size_type) [with _CharT = char;
_Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at
/build/gcc-master/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/basic_string.h:423:21,
    inlined from ‘static void std::__cxx11::basic_string<_CharT, _Traits,
_Alloc>::_S_copy(_CharT*, const _CharT*, size_type) [with _CharT = char;
_Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at
/build/gcc-master/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/basic_string.h:418:7,
    inlined from ‘std::__cxx11::basic_string<_CharT, _Traits, _Allocator>&
std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_M_replace(size_type,
size_type, const _CharT*, size_type) [with _CharT = char; _Traits =
std::char_traits<char>; _Alloc = std::allocator<char>]’ at
/build/gcc-master/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/basic_string.tcc:532:22,
    inlined from ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&
std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::assign(const _CharT*)
[with _CharT = char; _Traits = std::char_traits<char>; _Alloc =
std::allocator<char>]’ at
/build/gcc-master/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/basic_string.h:1647:19,
    inlined from ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&
std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=(const _CharT*)
[with _CharT = char; _Traits = std::char_traits<char>; _Alloc =
std::allocator<char>]’ at
/build/gcc-master/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/basic_string.h:815:28,
    inlined from ‘void f()’ at ../t.C:7:7:
/build/gcc-master/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/char_traits.h:431:56:
warning: ‘void* __builtin_memcpy(void*, const void*, long unsigned int)’
accessing 9223372036854775810 or more bytes at offsets -4611686018427387902 and
[-4611686018427387903, 4611686018427387904] may overlap up to
9223372036854775813 bytes at offset -3 [-Wrestrict]
  431 |         return static_cast<char_type*>(__builtin_memcpy(__s1, __s2,
__n));
      |                                       
~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~

^ permalink raw reply	[flat|nested] 5+ messages in thread
end of thread, other threads:[~2022-05-02 12:45 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2022-02-01 21:24 [Bug tree-optimization/104336] New: bogus -Wrestrict for std::string assignment with msebor at gcc dot gnu.org
2022-02-01 21:25 ` [Bug tree-optimization/104336] " msebor at gcc dot gnu.org
2022-04-25 19:11 ` mattias.ellert at physics dot uu.se
2022-04-25 20:26 ` amacleod at redhat dot com
2022-05-02 12:45 ` rguenth at gcc dot gnu.org

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