intermediate changes

ref:b701e8676af251d91697287754da22505ad43d4e

3 files changed, 40 insertions, 49 deletions

diff --git a/contrib/libs/cxxsupp/libcxx/include/__ranges/counted.h b/contrib/libs/cxxsupp/libcxx/include/__ranges/counted.h
index d292bcbb18..cb97840924 100644
--- a/contrib/libs/cxxsupp/libcxx/include/__ranges/counted.h
+++ b/contrib/libs/cxxsupp/libcxx/include/__ranges/counted.h
@@ -9,6 +9,7 @@
 #ifndef _LIBCPP___RANGES_COUNTED_H
 #define _LIBCPP___RANGES_COUNTED_H
 
+#include <__concepts/convertible_to.h>
 #include <__config>
 #include <__iterator/concepts.h>
 #include <__iterator/counted_iterator.h>
@@ -16,10 +17,7 @@
 #include <__iterator/incrementable_traits.h>
 #include <__iterator/iterator_traits.h>
 #include <__memory/pointer_traits.h>
-#include <__ranges/concepts.h>
 #include <__ranges/subrange.h>
-#include <__utility/decay_copy.h>
-#include <__utility/declval.h>
 #include <__utility/forward.h>
 #include <__utility/move.h>
 #include <span>
@@ -36,50 +34,39 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 namespace ranges::views {
 
 namespace __counted {
-  template<class _From, class _To>
-  concept __explicitly_convertible = requires {
-    _To(_From{});
-  };
 
   struct __fn {
-    template<class _Iter, class _Diff>
-      requires contiguous_iterator<decay_t<_Iter>> &&
-               __explicitly_convertible<_Diff, iter_difference_t<_Iter>>
+    template<contiguous_iterator _It>
     _LIBCPP_HIDE_FROM_ABI
-    constexpr auto operator()(_Iter&& __it, _Diff __c) const
-      noexcept(noexcept(
-        span(_VSTD::to_address(__it), static_cast<iter_difference_t<_Iter>>(__c))
-      ))
-    {
-      return span(_VSTD::to_address(__it), static_cast<iter_difference_t<_Iter>>(__c));
-    }
-
-    template<class _Iter, class _Diff>
-      requires random_access_iterator<decay_t<_Iter>> &&
-               __explicitly_convertible<_Diff, iter_difference_t<_Iter>>
+    static constexpr auto __go(_It __it, iter_difference_t<_It> __count)
+      noexcept(noexcept(span(_VSTD::to_address(__it), static_cast<size_t>(__count))))
+      // Deliberately omit return-type SFINAE, because to_address is not SFINAE-friendly
+      { return          span(_VSTD::to_address(__it), static_cast<size_t>(__count)); }
+
+    template<random_access_iterator _It>
     _LIBCPP_HIDE_FROM_ABI
-    constexpr auto operator()(_Iter&& __it, _Diff __c) const
-      noexcept(
-        noexcept(__it + static_cast<iter_difference_t<_Iter>>(__c)) &&
-        noexcept(ranges::subrange(_VSTD::forward<_Iter>(__it), _VSTD::__decay_copy(__it)))
-      )
-    {
-      auto __last = __it + static_cast<iter_difference_t<_Iter>>(__c);
-      return ranges::subrange(_VSTD::forward<_Iter>(__it), _VSTD::move(__last));
-    }
-
-    template<class _Iter, class _Diff>
-      requires __explicitly_convertible<_Diff, iter_difference_t<_Iter>>
+    static constexpr auto __go(_It __it, iter_difference_t<_It> __count)
+      noexcept(noexcept(subrange(__it, __it + __count)))
+      -> decltype(      subrange(__it, __it + __count))
+      { return          subrange(__it, __it + __count); }
+
+    template<class _It>
     _LIBCPP_HIDE_FROM_ABI
-    constexpr auto operator()(_Iter&& __it, _Diff __c) const
-      noexcept(noexcept(
-        ranges::subrange(counted_iterator(_VSTD::forward<_Iter>(__it), __c), default_sentinel)
-      ))
-    {
-      return ranges::subrange(counted_iterator(_VSTD::forward<_Iter>(__it), __c), default_sentinel);
-    }
+    static constexpr auto __go(_It __it, iter_difference_t<_It> __count)
+      noexcept(noexcept(subrange(counted_iterator(_VSTD::move(__it), __count), default_sentinel)))
+      -> decltype(      subrange(counted_iterator(_VSTD::move(__it), __count), default_sentinel))
+      { return          subrange(counted_iterator(_VSTD::move(__it), __count), default_sentinel); }
+
+    template<class _It, convertible_to<iter_difference_t<_It>> _Diff>
+      requires input_or_output_iterator<decay_t<_It>>
+    [[nodiscard]] _LIBCPP_HIDE_FROM_ABI
+    constexpr auto operator()(_It&& __it, _Diff&& __count) const
+      noexcept(noexcept(__go(_VSTD::forward<_It>(__it), _VSTD::forward<_Diff>(__count))))
+      -> decltype(      __go(_VSTD::forward<_It>(__it), _VSTD::forward<_Diff>(__count)))
+      { return          __go(_VSTD::forward<_It>(__it), _VSTD::forward<_Diff>(__count)); }
   };
-}
+
+} // namespace __counted
 
 inline namespace __cpo {
   inline constexpr auto counted = __counted::__fn{};
diff --git a/contrib/libs/cxxsupp/libcxx/include/__ranges/subrange.h b/contrib/libs/cxxsupp/libcxx/include/__ranges/subrange.h
index af4e276006..8e984f2bf0 100644
--- a/contrib/libs/cxxsupp/libcxx/include/__ranges/subrange.h
+++ b/contrib/libs/cxxsupp/libcxx/include/__ranges/subrange.h
@@ -91,14 +91,14 @@ namespace ranges {
     _LIBCPP_HIDE_FROM_ABI
     constexpr subrange(__convertible_to_non_slicing<_Iter> auto __iter, _Sent __sent)
       requires _MustProvideSizeAtConstruction
-      : __begin_(_VSTD::move(__iter)), __end_(std::move(__sent))
+      : __begin_(_VSTD::move(__iter)), __end_(_VSTD::move(__sent))
     { }
 
     _LIBCPP_HIDE_FROM_ABI
     constexpr subrange(__convertible_to_non_slicing<_Iter> auto __iter, _Sent __sent,
                        make_unsigned_t<iter_difference_t<_Iter>> __n)
       requires (_Kind == subrange_kind::sized)
-      : __begin_(_VSTD::move(__iter)), __end_(std::move(__sent)), __size_(__n)
+      : __begin_(_VSTD::move(__iter)), __end_(_VSTD::move(__sent)), __size_(__n)
     {
       if constexpr (sized_sentinel_for<_Sent, _Iter>)
         _LIBCPP_ASSERT((__end_ - __begin_) == static_cast<iter_difference_t<_Iter>>(__n),
diff --git a/contrib/libs/cxxsupp/libcxx/include/__ranges/transform_view.h b/contrib/libs/cxxsupp/libcxx/include/__ranges/transform_view.h
index 208a9a2269..0f53fbaa7e 100644
--- a/contrib/libs/cxxsupp/libcxx/include/__ranges/transform_view.h
+++ b/contrib/libs/cxxsupp/libcxx/include/__ranges/transform_view.h
@@ -46,11 +46,15 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
 
+template<class _Fn, class _View>
+concept __regular_invocable_with_range_ref =
+  regular_invocable<_Fn, range_reference_t<_View>>;
+
 template<class _View, class _Fn>
 concept __transform_view_constraints =
-           view<_View> && is_object_v<_Fn> &&
-           regular_invocable<_Fn&, range_reference_t<_View>> &&
-           __referenceable<invoke_result_t<_Fn&, range_reference_t<_View>>>;
+  view<_View> && is_object_v<_Fn> &&
+  regular_invocable<_Fn&, range_reference_t<_View>> &&
+  __referenceable<invoke_result_t<_Fn&, range_reference_t<_View>>>;
 
 template<input_range _View, copy_constructible _Fn>
   requires __transform_view_constraints<_View, _Fn>
@@ -82,7 +86,7 @@ public:
   _LIBCPP_HIDE_FROM_ABI
   constexpr __iterator<true> begin() const
     requires range<const _View> &&
-             regular_invocable<const _Fn&, range_reference_t<const _View>>
+             __regular_invocable_with_range_ref<const _Fn&, const _View>
   {
     return __iterator<true>(*this, ranges::begin(__base_));
   }
@@ -100,14 +104,14 @@ public:
   _LIBCPP_HIDE_FROM_ABI
   constexpr __sentinel<true> end() const
     requires range<const _View> &&
-             regular_invocable<const _Fn&, range_reference_t<const _View>>
+             __regular_invocable_with_range_ref<const _Fn&, const _View>
   {
     return __sentinel<true>(ranges::end(__base_));
   }
   _LIBCPP_HIDE_FROM_ABI
   constexpr __iterator<true> end() const
     requires common_range<const _View> &&
-             regular_invocable<const _Fn&, range_reference_t<const _View>>
+             __regular_invocable_with_range_ref<const _Fn&, const _View>
   {
     return __iterator<true>(*this, ranges::end(__base_));
   }