[libc++][ranges] Implement `ranges::rotate`.
Also fix `ranges::stable_sort` and `ranges::inplace_merge` to support
proxy iterators now that their internal implementations can correctly
dispatch `rotate`.
Differential Revision: https://reviews.llvm.org/D130758
diff --git a/libcxx/include/algorithm b/libcxx/include/algorithm
index 6da0146..ab5ad55 100644
--- a/libcxx/include/algorithm
+++ b/libcxx/include/algorithm
@@ -745,6 +745,13 @@
constexpr ranges::reverse_copy_result<borrowed_iterator_t<R>, O>
ranges::reverse_copy(R&& r, O result); // since C++20
+ template<permutable I, sentinel_for<I> S>
+ constexpr subrange<I> rotate(I first, I middle, S last); // since C++20
+
+ template<forward_range R>
+ requires permutable<iterator_t<R>>
+ constexpr borrowed_subrange_t<R> rotate(R&& r, iterator_t<R> middle); // Since C++20
+
template <class _InIter, class _OutIter>
using rotate_copy_result = in_out_result<_InIter, _OutIter>; // since C++20
@@ -1817,6 +1824,7 @@
#include <__algorithm/ranges_replace_if.h>
#include <__algorithm/ranges_reverse.h>
#include <__algorithm/ranges_reverse_copy.h>
+#include <__algorithm/ranges_rotate.h>
#include <__algorithm/ranges_rotate_copy.h>
#include <__algorithm/ranges_sample.h>
#include <__algorithm/ranges_search.h>
