[libcxx-commits] [libcxx] [libcxx] Added segment iterator for fill (PR #104680)

[Nikolas Klauser via libcxx-commits]

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@@ -21,23 +21,64 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 
 // fill isn't specialized for std::memset, because the compiler already optimizes the loop to a call to std::memset.
 
-template <class _ForwardIterator, class _Tp>
+template <
+    class _ForwardIterator,
+    class _Tp,
+    __enable_if_t<
+        is_same<typename iterator_traits<_ForwardIterator>::iterator_category, forward_iterator_tag>::value ||
+            is_same<typename iterator_traits<_ForwardIterator>::iterator_category, bidirectional_iterator_tag>::value,
+        int> = 0>
 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void
-__fill(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value, forward_iterator_tag) {
+__fill(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value) {
   for (; __first != __last; ++__first)
     *__first = __value;
 }
 
-template <class _RandomAccessIterator, class _Tp>
+template <class _RandomAccessIterator,
+          class _Tp,
+          __enable_if_t<(is_same<typename iterator_traits<_RandomAccessIterator>::iterator_category,
+                                 random_access_iterator_tag>::value ||
+                         is_same<typename iterator_traits<_RandomAccessIterator>::iterator_category,
+                                 contiguous_iterator_tag>::value) &&
+                            !__is_segmented_iterator<_RandomAccessIterator>::value,
+                        int> = 0>
 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void
-__fill(_RandomAccessIterator __first, _RandomAccessIterator __last, const _Tp& __value, random_access_iterator_tag) {
+__fill(_RandomAccessIterator __first, _RandomAccessIterator __last, const _Tp& __value) {
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philnik777 wrote:

Have you looked into how to combine this with `fill_n`? They are very similar algorithms after all.

https://github.com/llvm/llvm-project/pull/104680