https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109849
--- Comment #32 from Jan Hubicka <hubicka at ucw dot cz> --- > /tmp/build/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/stl_algobase.h:437: > warning: 'void* __builtin_memcpy(void*, const void*, long unsigned int)' > writing between 2 and 9223372036854775806 bytes into a region of size 0 > overflows the destination [-Wstringop-overflow=] It warns on: template<bool _IsMove> struct __copy_move<_IsMove, true, random_access_iterator_tag> { template<typename _Tp, typename _Up> _GLIBCXX20_CONSTEXPR static _Up* __copy_m(_Tp* __first, _Tp* __last, _Up* __result) { const ptrdiff_t _Num = __last - __first; if (__builtin_expect(_Num > 1, true)) __builtin_memmove(__result, __first, sizeof(_Tp) * _Num); else if (_Num == 1) std::__copy_move<_IsMove, false, random_access_iterator_tag>:: __assign_one(__result, __first); return __result + _Num; } }; It is likely false positive on a code path that never happens in real code, but we now optimize it better. Does it show an inline path?