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From: "dennis-hezel at gmx dot de" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/101485] New: Calling std::equal with std::byte* does not use memcmp Date: Sat, 17 Jul 2021 11:56:20 +0000 [thread overview] Message-ID: <bug-101485-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101485 Bug ID: 101485 Summary: Calling std::equal with std::byte* does not use memcmp Product: gcc Version: 12.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: dennis-hezel at gmx dot de Target Milestone: --- See https://godbolt.org/z/fKbhqe1sz ``` #include <algorithm> auto equal_with_bytes(std::byte* b1, std::byte* e1, std::byte* b2) { return std::equal(b1, e1, b2); } auto equal_with_chars(unsigned char* b1, unsigned char* e1, unsigned char* b2) { return std::equal(b1, e1, b2); } ``` In the above code `equal_with_chars` invokes `memcmp` while `equal_with_bytes` does not, although it would be eligble. The problematic code seems to be in `stl_algobase.h` ``` template<typename _II1, typename _II2> _GLIBCXX20_CONSTEXPR inline bool __equal_aux1(_II1 __first1, _II1 __last1, _II2 __first2) { typedef typename iterator_traits<_II1>::value_type _ValueType1; const bool __simple = ((__is_integer<_ValueType1>::__value || __is_pointer<_ValueType1>::__value) && __memcmpable<_II1, _II2>::__value); return std::__equal<__simple>::equal(__first1, __last1, __first2); } ``` since `std::byte` is neither an integer nor a pointer. Suggested fix: Extend the condition with a check for `std::byte` ``` __is_integer<_ValueType1>::__value || __is_pointer<_ValueType1>::__value || __is_byte<_ValueType1>::__value ```
next reply other threads:[~2021-07-17 11:56 UTC|newest] Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-07-17 11:56 dennis-hezel at gmx dot de [this message] 2021-07-18 21:14 ` [Bug libstdc++/101485] " redi at gcc dot gnu.org
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