stringop-overflow warnings with gcc 14.2

[ZedThree]

Building current master (925234) with gcc 14.2.1 gives me a bunch of warnings about "reading/writing 128 bytes from a region of size 16":

In file included from /usr/include/c++/14/string:51,
                 from /home/peter/Tools/ADIOS2/source/adios2/core/AttributeBase.h:15,
                 from /home/peter/Tools/ADIOS2/source/adios2/core/Attribute.h:14,
                 from /home/peter/Tools/ADIOS2/source/adios2/toolkit/format/bp5/BP5Base.h:11,
                 from /home/peter/Tools/ADIOS2/source/adios2/toolkit/format/bp5/BP5Helper.h:11,
                 from /home/peter/Tools/ADIOS2/source/adios2/toolkit/format/bp5/BP5Helper.cpp:8:
In static member function ‘static _Up* std::__copy_move<_IsMove, true, std::random_access_iterator_tag>::__copy_m(_Tp*, _Tp*, _Up*) [with _Tp = const char; _Up = char; bool _IsMove = false]’,
    inlined from ‘_OI std::__copy_move_a2(_II, _II, _OI) [with bool _IsMove = false; _II = const char*; _OI = char*]’ at /usr/include/c++/14/bits/stl_algobase.h:521:30,
    inlined from ‘_OI std::__copy_move_a1(_II, _II, _OI) [with bool _IsMove = false; _II = const char*; _OI = char*]’ at /usr/include/c++/14/bits/stl_algobase.h:548:42,
    inlined from ‘_OI std::__copy_move_a(_II, _II, _OI) [with bool _IsMove = false; _II = const char*; _OI = __gnu_cxx::__normal_iterator<char*, vector<char> >]’ at /usr/include/c++/14/bits/stl_algobase.h:555:31,
    inlined from ‘_OI std::copy(_II, _II, _OI) [with _II = const char*; _OI = __gnu_cxx::__normal_iterator<char*, vector<char> >]’ at /usr/include/c++/14/bits/stl_algobase.h:651:7,
    inlined from ‘void adios2::helper::CopyToBuffer(std::vector<char>&, std::size_t&, const T*, std::size_t) [with T = long unsigned int]’ at /home/peter/Tools/ADIOS2/source/adios2/helper/adiosMemory.inl:144:14,
    inlined from ‘static std::vector<char> adios2::format::BP5Helper::BuildNodeContrib(digest, std::size_t, std::vector<adios2::format::BP5Base::MetaMetaInfoBlock>, std::size_t, std::vector<long unsigned int>)’ at /home/peter/Tools/ADIOS2/source/adios2/toolkit/format/bp5/BP5Helper.cpp:61:25:
/usr/include/c++/14/bits/stl_algobase.h:452:30: warning: ‘void* __builtin_memcpy(void*, const void*, long unsigned int)’ reading 128 bytes from a region of size 16 [-Wstringop-overread]
  452 |             __builtin_memmove(__result, __first, sizeof(_Tp) * _Num);
      |             ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/peter/Tools/ADIOS2/source/adios2/toolkit/format/bp5/BP5Helper.cpp: In static member function ‘static std::vector<char> adios2::format::BP5Helper::BuildNodeContrib(digest, std::size_t, std::vector<adios2::format::BP5Base::MetaMetaInfoBlock>, std::size_t, std::vector<long unsigned int>)’:
/home/peter/Tools/ADIOS2/source/adios2/toolkit/format/bp5/BP5Helper.cpp:49:42: note: source object ‘attrHash’ of size 16
   49 | BP5Helper::BuildNodeContrib(const digest attrHash, const size_t attrSize,
      |                             ~~~~~~~~~~~~~^~~~~~~~
In static member function ‘static _Up* std::__copy_move<_IsMove, true, std::random_access_iterator_tag>::__copy_m(_Tp*, _Tp*, _Up*) [with _Tp = const char; _Up = char; bool _IsMove = false]’,
    inlined from ‘_OI std::__copy_move_a2(_II, _II, _OI) [with bool _IsMove = false; _II = const char*; _OI = char*]’ at /usr/include/c++/14/bits/stl_algobase.h:521:30,
    inlined from ‘_OI std::__copy_move_a1(_II, _II, _OI) [with bool _IsMove = false; _II = const char*; _OI = char*]’ at /usr/include/c++/14/bits/stl_algobase.h:548:42,
    inlined from ‘_OI std::__copy_move_a(_II, _II, _OI) [with bool _IsMove = false; _II = const char*; _OI = __gnu_cxx::__normal_iterator<char*, vector<char> >]’ at /usr/include/c++/14/bits/stl_algobase.h:555:31,
    inlined from ‘_OI std::copy(_II, _II, _OI) [with _II = const char*; _OI = __gnu_cxx::__normal_iterator<char*, vector<char> >]’ at /usr/include/c++/14/bits/stl_algobase.h:651:7,
    inlined from ‘void adios2::helper::CopyToBuffer(std::vector<char>&, std::size_t&, const T*, std::size_t) [with T = long unsigned int]’ at /home/peter/Tools/ADIOS2/source/adios2/helper/adiosMemory.inl:144:14,
    inlined from ‘static std::vector<char> adios2::format::BP5Helper::BuildNodeContrib(digest, std::size_t, std::vector<adios2::format::BP5Base::MetaMetaInfoBlock>, std::size_t, std::vector<long unsigned int>)’ at /home/peter/Tools/ADIOS2/source/adios2/toolkit/format/bp5/BP5Helper.cpp:68:29:
/usr/include/c++/14/bits/stl_algobase.h:452:30: warning: ‘void* __builtin_memcpy(void*, const void*, long unsigned int)’ reading 128 bytes from a region of size 16 [-Wstringop-overread]
  452 |             __builtin_memmove(__result, __first, sizeof(_Tp) * _Num);
      |             ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/peter/Tools/ADIOS2/source/adios2/toolkit/format/bp5/BP5Helper.cpp: In static member function ‘static std::vector<char> adios2::format::BP5Helper::BuildNodeContrib(digest, std::size_t, std::vector<adios2::format::BP5Base::MetaMetaInfoBlock>, std::size_t, std::vector<long unsigned int>)’:
/home/peter/Tools/ADIOS2/source/adios2/toolkit/format/bp5/BP5Helper.cpp:66:16: note: source object ‘D’ of size 16
   66 |         digest D;
      |                ^
In static member function ‘static _Up* std::__copy_move<_IsMove, true, std::random_access_iterator_tag>::__copy_m(_Tp*, _Tp*, _Up*) [with _Tp = const char; _Up = char; bool _IsMove = false]’,
    inlined from ‘_OI std::__copy_move_a2(_II, _II, _OI) [with bool _IsMove = false; _II = const char*; _OI = char*]’ at /usr/include/c++/14/bits/stl_algobase.h:521:30,
    inlined from ‘_OI std::__copy_move_a1(_II, _II, _OI) [with bool _IsMove = false; _II = const char*; _OI = char*]’ at /usr/include/c++/14/bits/stl_algobase.h:548:42,
    inlined from ‘_OI std::__copy_move_a(_II, _II, _OI) [with bool _IsMove = false; _II = const char*; _OI = char*]’ at /usr/include/c++/14/bits/stl_algobase.h:555:31,
    inlined from ‘_OI std::copy(_II, _II, _OI) [with _II = const char*; _OI = char*]’ at /usr/include/c++/14/bits/stl_algobase.h:651:7,
    inlined from ‘void adios2::helper::CopyFromBuffer(const char*, std::size_t&, T*, std::size_t) [with T = long unsigned int]’ at /home/peter/Tools/ADIOS2/source/adios2/helper/adiosMemory.inl:220:14,
    inlined from ‘void adios2::helper::ReadArray(const std::vector<char>&, std::size_t&, T*, std::size_t, bool) [with T = long unsigned int]’ at /home/peter/Tools/ADIOS2/source/adios2/helper/adiosMemory.inl:333:19,
    inlined from ‘static void adios2::format::BP5Helper::BreakdownIncomingMInfo(std::vector<long unsigned int>, std::vector<char>, std::vector<long unsigned int>&, std::vector<long unsigned int>&, std::vector<long unsigned int>&, std::vector<long unsigned int>&, std::vector<long unsigned int>&, std::vector<long unsigned int>&, std::vector<digest>&)’ at /home/peter/Tools/ADIOS2/source/adios2/toolkit/format/bp5/BP5Helper.cpp:199:26:
/usr/include/c++/14/bits/stl_algobase.h:452:30: warning: ‘void* __builtin_memcpy(void*, const void*, long unsigned int)’ writing 128 bytes into a region of size 16 overflows the destination [-Wstringop-overflow=]
  452 |             __builtin_memmove(__result, __first, sizeof(_Tp) * _Num);
      |             ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/peter/Tools/ADIOS2/source/adios2/toolkit/format/bp5/BP5Helper.cpp: In static member function ‘static void adios2::format::BP5Helper::BreakdownIncomingMInfo(std::vector<long unsigned int>, std::vector<char>, std::vector<long unsigned int>&, std::vector<long unsigned int>&, std::vector<long unsigned int>&, std::vector<long unsigned int>&, std::vector<long unsigned int>&, std::vector<long unsigned int>&, std::vector<digest>&)’:
/home/peter/Tools/ADIOS2/source/adios2/toolkit/format/bp5/BP5Helper.cpp:195:16: note: destination object ‘thisAttrHash’ of size 16
  195 |         digest thisAttrHash;
      |                ^~~~~~~~~~~~
In static member function ‘static _Up* std::__copy_move<_IsMove, true, std::random_access_iterator_tag>::__copy_m(_Tp*, _Tp*, _Up*) [with _Tp = const char; _Up = char; bool _IsMove = false]’,
    inlined from ‘_OI std::__copy_move_a2(_II, _II, _OI) [with bool _IsMove = false; _II = const char*; _OI = char*]’ at /usr/include/c++/14/bits/stl_algobase.h:521:30,
    inlined from ‘_OI std::__copy_move_a1(_II, _II, _OI) [with bool _IsMove = false; _II = const char*; _OI = char*]’ at /usr/include/c++/14/bits/stl_algobase.h:548:42,
    inlined from ‘_OI std::__copy_move_a(_II, _II, _OI) [with bool _IsMove = false; _II = const char*; _OI = char*]’ at /usr/include/c++/14/bits/stl_algobase.h:555:31,
    inlined from ‘_OI std::copy(_II, _II, _OI) [with _II = const char*; _OI = char*]’ at /usr/include/c++/14/bits/stl_algobase.h:651:7,
    inlined from ‘void adios2::helper::CopyFromBuffer(const char*, std::size_t&, T*, std::size_t) [with T = long unsigned int]’ at /home/peter/Tools/ADIOS2/source/adios2/helper/adiosMemory.inl:220:14,
    inlined from ‘void adios2::helper::ReadArray(const std::vector<char>&, std::size_t&, T*, std::size_t, bool) [with T = long unsigned int]’ at /home/peter/Tools/ADIOS2/source/adios2/helper/adiosMemory.inl:333:19,
    inlined from ‘static void adios2::format::BP5Helper::BreakdownIncomingMInfo(std::vector<long unsigned int>, std::vector<char>, std::vector<long unsigned int>&, std::vector<long unsigned int>&, std::vector<long unsigned int>&, std::vector<long unsigned int>&, std::vector<long unsigned int>&, std::vector<long unsigned int>&, std::vector<digest>&)’ at /home/peter/Tools/ADIOS2/source/adios2/toolkit/format/bp5/BP5Helper.cpp:215:30:
/usr/include/c++/14/bits/stl_algobase.h:452:30: warning: ‘void* __builtin_memcpy(void*, const void*, long unsigned int)’ writing 128 bytes into a region of size 16 overflows the destination [-Wstringop-overflow=]
  452 |             __builtin_memmove(__result, __first, sizeof(_Tp) * _Num);
      |             ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/peter/Tools/ADIOS2/source/adios2/toolkit/format/bp5/BP5Helper.cpp: In static member function ‘static void adios2::format::BP5Helper::BreakdownIncomingMInfo(std::vector<long unsigned int>, std::vector<char>, std::vector<long unsigned int>&, std::vector<long unsigned int>&, std::vector<long unsigned int>&, std::vector<long unsigned int>&, std::vector<long unsigned int>&, std::vector<long unsigned int>&, std::vector<digest>&)’:
/home/peter/Tools/ADIOS2/source/adios2/toolkit/format/bp5/BP5Helper.cpp:214:20: note: destination object ‘thisMMB’ of size 16
  214 |             digest thisMMB;
      |                    ^~~~~~~

Offending code is in BP5Helper::BuildNodeContrib:

helper::CopyToBuffer(ret, position, &attrHash.x[0], sizeof(digest));

(and similar)

My completely naive guess is that the last argument to CopyToBuffer is the number of elements, so this should probably be the following instead?

helper::CopyToBuffer(ret, position, &attrHash.x[0], 2);

Configured like:

$ cmake . -B build -DADIOS2_USE_MPI=on -DADIOS2_USE_Fortran=off -DADIOS2_USE_Python=off -DADIOS2_BUILD_EXAMPLES=OFF -DADIOS2_USE_SST=off -GNinja