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
```
