================
@@ -10,32 +10,88 @@
#ifndef _LIBCPP___ALGORITHM_FOR_EACH_N_H
#define _LIBCPP___ALGORITHM_FOR_EACH_N_H
+#include <__algorithm/for_each.h>
+#include <__algorithm/for_each_n_segment.h>
#include <__config>
+#include <__iterator/iterator_traits.h>
+#include <__iterator/segmented_iterator.h>
+#include <__type_traits/enable_if.h>
#include <__utility/convert_to_integral.h>
+#include <__utility/move.h>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
-_LIBCPP_BEGIN_NAMESPACE_STD
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
-#if _LIBCPP_STD_VER >= 17
+_LIBCPP_BEGIN_NAMESPACE_STD
-template <class _InputIterator, class _Size, class _Function>
-inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _InputIterator
-for_each_n(_InputIterator __first, _Size __orig_n, _Function __f) {
+template <class _InputIterator,
+ class _Size,
+ class _Func,
+ __enable_if_t<!__has_random_access_iterator_category<_InputIterator>::value &&
+ (!__is_segmented_iterator<_InputIterator>::value
+ // || !__has_random_access_iterator_category<
+ // typename __segmented_iterator_traits<_InputIterator>::__local_iterator>::value
+ ), // TODO: __segmented_iterator_traits<_InputIterator> results in template instantiation
+ // during SFINAE, which is a hard error to be fixed. Once fixed, we should uncomment.
+ int> = 0>
----------------
ldionne wrote:
Instead, I would suggest this:
```
template <class _SegmentedIterator>
struct __has_random_access_local_iterator
: __has_random_access_iterator_category<
typename __segmented_iterator_traits< _SegmentedIterator >::__local_iterator
>
{ };
// Then, use:
__enable_if_t<
!__has_random_access_iterator_category<_InputIterator>::value &&
_Or<
_Not<__is_segmented_iterator<_InputIterator> >,
_Not<__has_random_access_local_iterator<_InputIterator> >
>::value
>
```
The difference here is that `_Or` is performing lazy evaluation of its operands, so `__has_random_access_local_iterator` never gets instantiated if we don't have a segmented iterator.
IMO this also removes the need for https://github.com/llvm/llvm-project/pull/134304.
https://github.com/llvm/llvm-project/pull/135468