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* [Bug libstdc++/105562] New: [12 Regression] std::function<bool(char)>::_M_invoker may be used uninitialized in std:regex move with -fno-strict-aliasing
@ 2022-05-11 10:48 andrey.vihrov at gmail dot com
  2022-05-11 10:55 ` [Bug libstdc++/105562] [12/13 Regression] std::function<bool(char)>::_M_invoker may be used uninitialized in std::regex move with -fno-strict-aliasing since r12-6216-g5a431b60d1f22199 marxin at gcc dot gnu.org
                   ` (26 more replies)
  0 siblings, 27 replies; 28+ messages in thread
From: andrey.vihrov at gmail dot com @ 2022-05-11 10:48 UTC (permalink / raw)
  To: gcc-bugs

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105562

            Bug ID: 105562
           Summary: [12 Regression] std::function<bool(char)>::_M_invoker
                    may be used uninitialized in std:regex move with
                    -fno-strict-aliasing
           Product: gcc
           Version: 12.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: andrey.vihrov at gmail dot com
  Target Milestone: ---

Consider the following sample:

  #include <regex>

  int main()
  {
    std::regex a(".");
    std::regex b(std::move(a));
  }

Since GCC 12.1, compiling this code with "g++ -Wall -O1 -fno-strict-aliasing
x.cpp" gives

In file included from /usr/include/c++/12.1.0/regex:48,
                 from x.cpp:1:
In constructor 'std::function<_Res(_ArgTypes
...)>::function(std::function<_Res(_ArgTypes ...)>&&) [with _Res = bool;
_ArgTypes = {char}]',
    inlined from
'std::__detail::_State<_Char_type>::_State(std::__detail::_State<_Char_type>&&)
[with _Char_type = char]' at
/usr/include/c++/12.1.0/bits/regex_automaton.h:149:4,
    inlined from 'std::__detail::_StateIdT
std::__detail::_NFA<_TraitsT>::_M_insert_subexpr_end() [with _TraitsT =
std::__cxx11::regex_traits<char>]' at
/usr/include/c++/12.1.0/bits/regex_automaton.h:290:24:
/usr/include/c++/12.1.0/bits/std_function.h:405:42: warning:
'*(std::function<bool(char)>*)((char*)&__tmp + offsetof(std::__detail::_StateT,
std::__detail::_State<char>::<unnamed>.std::__detail::_State_base::<unnamed>)).std::function<bool(char)>::_M_invoker'
may be used uninitialized [-Wmaybe-uninitialized]
  405 |       : _Function_base(), _M_invoker(__x._M_invoker)
      |                                      ~~~~^~~~~~~~~~
In file included from /usr/include/c++/12.1.0/regex:63:
/usr/include/c++/12.1.0/bits/regex_automaton.h: In member function
'std::__detail::_StateIdT
std::__detail::_NFA<_TraitsT>::_M_insert_subexpr_end() [with _TraitsT =
std::__cxx11::regex_traits<char>]':
/usr/include/c++/12.1.0/bits/regex_automaton.h:287:17: note: '__tmp' declared
here
  287 |         _StateT __tmp(_S_opcode_subexpr_end);
      |                 ^~~~~
In member function 'bool std::_Function_base::_M_empty() const',
    inlined from 'std::function<_Res(_ArgTypes ...)>::operator bool() const
[with _Res = bool; _ArgTypes = {char}]' at
/usr/include/c++/12.1.0/bits/std_function.h:574:25,
    inlined from 'std::function<_Res(_ArgTypes
...)>::function(std::function<_Res(_ArgTypes ...)>&&) [with _Res = bool;
_ArgTypes = {char}]' at /usr/include/c++/12.1.0/bits/std_function.h:407:6,
    inlined from
'std::__detail::_State<_Char_type>::_State(std::__detail::_State<_Char_type>&&)
[with _Char_type = char]' at
/usr/include/c++/12.1.0/bits/regex_automaton.h:149:4,
    inlined from 'std::__detail::_StateIdT
std::__detail::_NFA<_TraitsT>::_M_insert_subexpr_end() [with _TraitsT =
std::__cxx11::regex_traits<char>]' at
/usr/include/c++/12.1.0/bits/regex_automaton.h:290:24:
/usr/include/c++/12.1.0/bits/std_function.h:247:37: warning: '*(const
std::_Function_base*)((char*)&__tmp + offsetof(std::__detail::_StateT,
std::__detail::_State<char>::<unnamed>.std::__detail::_State_base::<unnamed>)).std::_Function_base::_M_manager'
may be used uninitialized [-Wmaybe-uninitialized]
  247 |     bool _M_empty() const { return !_M_manager; }
      |                                     ^~~~~~~~~~
/usr/include/c++/12.1.0/bits/regex_automaton.h: In member function
'std::__detail::_StateIdT
std::__detail::_NFA<_TraitsT>::_M_insert_subexpr_end() [with _TraitsT =
std::__cxx11::regex_traits<char>]':
/usr/include/c++/12.1.0/bits/regex_automaton.h:287:17: note: '__tmp' declared
here
  287 |         _StateT __tmp(_S_opcode_subexpr_end);
      |                 ^~~~~


There are no warnings with -fstrict-aliasing. Related resources:
* https://gcc.gnu.org/pipermail/gcc/2021-July/236851.html
* https://gcc.gnu.org/g:c22bcfd2f7dc9bb5ad394720f4a612327dc898ba

^ permalink raw reply	[flat|nested] 28+ messages in thread

end of thread, other threads:[~2023-12-06 11:16 UTC | newest]

Thread overview: 28+ messages (download: mbox.gz / follow: Atom feed)
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2022-05-11 10:48 [Bug libstdc++/105562] New: [12 Regression] std::function<bool(char)>::_M_invoker may be used uninitialized in std:regex move with -fno-strict-aliasing andrey.vihrov at gmail dot com
2022-05-11 10:55 ` [Bug libstdc++/105562] [12/13 Regression] std::function<bool(char)>::_M_invoker may be used uninitialized in std::regex move with -fno-strict-aliasing since r12-6216-g5a431b60d1f22199 marxin at gcc dot gnu.org
2022-05-11 11:05 ` rguenth at gcc dot gnu.org
2022-05-11 11:32 ` andrey.vihrov at gmail dot com
2022-05-11 11:54 ` redi at gcc dot gnu.org
2022-05-11 12:44 ` [Bug libstdc++/105562] std::function<bool(char)>::_M_invoker may be used uninitialized in std::regex move with -fno-strict-aliasing redi at gcc dot gnu.org
2022-05-11 12:56 ` redi at gcc dot gnu.org
2022-05-11 12:57 ` redi at gcc dot gnu.org
2022-05-11 12:59 ` redi at gcc dot gnu.org
2022-05-12  9:27 ` jakub at gcc dot gnu.org
2022-05-12  9:35 ` jakub at gcc dot gnu.org
2022-05-12  9:54 ` rguenth at gcc dot gnu.org
2022-05-12  9:57 ` rguenth at gcc dot gnu.org
2022-05-12 10:07 ` rguenth at gcc dot gnu.org
2022-05-12 11:27 ` cvs-commit at gcc dot gnu.org
2022-05-12 11:28 ` [Bug libstdc++/105562] [12 Regression] " rguenth at gcc dot gnu.org
2022-05-19 12:47 ` cvs-commit at gcc dot gnu.org
2022-05-19 12:50 ` rguenth at gcc dot gnu.org
2022-10-22  0:50 ` pinskia at gcc dot gnu.org
2023-05-26 21:40 ` urisimchoni at gmail dot com
2023-09-12 12:04 ` jakub1miernik at gmail dot com
2023-12-06 10:03 ` romain.geissler at amadeus dot com
2023-12-06 10:26 ` rguenth at gcc dot gnu.org
2023-12-06 10:35 ` romain.geissler at amadeus dot com
2023-12-06 10:43 ` rguenther at suse dot de
2023-12-06 10:50 ` jakub at gcc dot gnu.org
2023-12-06 11:13 ` romain.geissler at amadeus dot com
2023-12-06 11:16 ` sjames at gcc dot gnu.org

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