diff --git a/libcxx/include/__algorithm/ranges_adjacent_find.h b/libcxx/include/__algorithm/ranges_adjacent_find.h
index 3c54f723310a..0f2cb6669937 100644
--- a/libcxx/include/__algorithm/ranges_adjacent_find.h
+++ b/libcxx/include/__algorithm/ranges_adjacent_find.h
@@ -32,8 +32,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __adjacent_find {
-struct __fn {
+struct __adjacent_find {
   template <class _Iter, class _Sent, class _Proj, class _Pred>
   _LIBCPP_HIDE_FROM_ABI constexpr static _Iter
   __adjacent_find_impl(_Iter __first, _Sent __last, _Pred& __pred, _Proj& __proj) {
@@ -67,10 +66,9 @@ struct __fn {
     return __adjacent_find_impl(ranges::begin(__range), ranges::end(__range), __pred, __proj);
   }
 };
-} // namespace __adjacent_find
 
 inline namespace __cpo {
-inline constexpr auto adjacent_find = __adjacent_find::__fn{};
+inline constexpr auto adjacent_find = __adjacent_find{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_all_of.h b/libcxx/include/__algorithm/ranges_all_of.h
index 2f603b32f32d..fea089493811 100644
--- a/libcxx/include/__algorithm/ranges_all_of.h
+++ b/libcxx/include/__algorithm/ranges_all_of.h
@@ -30,8 +30,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __all_of {
-struct __fn {
+struct __all_of {
   template <class _Iter, class _Sent, class _Proj, class _Pred>
   _LIBCPP_HIDE_FROM_ABI constexpr static bool __all_of_impl(_Iter __first, _Sent __last, _Pred& __pred, _Proj& __proj) {
     for (; __first != __last; ++__first) {
@@ -58,10 +57,9 @@ struct __fn {
     return __all_of_impl(ranges::begin(__range), ranges::end(__range), __pred, __proj);
   }
 };
-} // namespace __all_of
 
 inline namespace __cpo {
-inline constexpr auto all_of = __all_of::__fn{};
+inline constexpr auto all_of = __all_of{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_any_of.h b/libcxx/include/__algorithm/ranges_any_of.h
index 205fcecc086e..34d23b4b7455 100644
--- a/libcxx/include/__algorithm/ranges_any_of.h
+++ b/libcxx/include/__algorithm/ranges_any_of.h
@@ -30,8 +30,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __any_of {
-struct __fn {
+struct __any_of {
   template <class _Iter, class _Sent, class _Proj, class _Pred>
   _LIBCPP_HIDE_FROM_ABI constexpr static bool __any_of_impl(_Iter __first, _Sent __last, _Pred& __pred, _Proj& __proj) {
     for (; __first != __last; ++__first) {
@@ -58,10 +57,9 @@ struct __fn {
     return __any_of_impl(ranges::begin(__range), ranges::end(__range), __pred, __proj);
   }
 };
-} // namespace __any_of
 
 inline namespace __cpo {
-inline constexpr auto any_of = __any_of::__fn{};
+inline constexpr auto any_of = __any_of{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_binary_search.h b/libcxx/include/__algorithm/ranges_binary_search.h
index 1ef2bd62b599..47bd0997334e 100644
--- a/libcxx/include/__algorithm/ranges_binary_search.h
+++ b/libcxx/include/__algorithm/ranges_binary_search.h
@@ -32,8 +32,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __binary_search {
-struct __fn {
+struct __binary_search {
   template <forward_iterator _Iter,
             sentinel_for<_Iter> _Sent,
             class _Type,
@@ -57,10 +56,9 @@ struct __fn {
     return __ret != __last && !std::invoke(__comp, __value, std::invoke(__proj, *__ret));
   }
 };
-} // namespace __binary_search
 
 inline namespace __cpo {
-inline constexpr auto binary_search = __binary_search::__fn{};
+inline constexpr auto binary_search = __binary_search{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_clamp.h b/libcxx/include/__algorithm/ranges_clamp.h
index e6181ef9435e..4bb3e46e73bd 100644
--- a/libcxx/include/__algorithm/ranges_clamp.h
+++ b/libcxx/include/__algorithm/ranges_clamp.h
@@ -30,8 +30,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __clamp {
-struct __fn {
+struct __clamp {
   template <class _Type,
             class _Proj                                                      = identity,
             indirect_strict_weak_order<projected<const _Type*, _Proj>> _Comp = ranges::less>
@@ -50,10 +49,9 @@ struct __fn {
       return __value;
   }
 };
-} // namespace __clamp
 
 inline namespace __cpo {
-inline constexpr auto clamp = __clamp::__fn{};
+inline constexpr auto clamp = __clamp{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_contains.h b/libcxx/include/__algorithm/ranges_contains.h
index 4836c3baed17..88de215297e5 100644
--- a/libcxx/include/__algorithm/ranges_contains.h
+++ b/libcxx/include/__algorithm/ranges_contains.h
@@ -33,8 +33,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __contains {
-struct __fn {
+struct __contains {
   template <input_iterator _Iter, sentinel_for<_Iter> _Sent, class _Type, class _Proj = identity>
     requires indirect_binary_predicate<ranges::equal_to, projected<_Iter, _Proj>, const _Type*>
   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr bool static
@@ -50,10 +49,9 @@ struct __fn {
            ranges::end(__range);
   }
 };
-} // namespace __contains
 
 inline namespace __cpo {
-inline constexpr auto contains = __contains::__fn{};
+inline constexpr auto contains = __contains{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_contains_subrange.h b/libcxx/include/__algorithm/ranges_contains_subrange.h
index 4398c457fd05..e8740d69dbef 100644
--- a/libcxx/include/__algorithm/ranges_contains_subrange.h
+++ b/libcxx/include/__algorithm/ranges_contains_subrange.h
@@ -35,8 +35,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __contains_subrange {
-struct __fn {
+struct __contains_subrange {
   template <forward_iterator _Iter1,
             sentinel_for<_Iter1> _Sent1,
             forward_iterator _Iter2,
@@ -81,10 +80,9 @@ struct __fn {
     return __ret.empty() == false;
   }
 };
-} // namespace __contains_subrange
 
 inline namespace __cpo {
-inline constexpr auto contains_subrange = __contains_subrange::__fn{};
+inline constexpr auto contains_subrange = __contains_subrange{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_copy.h b/libcxx/include/__algorithm/ranges_copy.h
index e1d6d32f05f7..05b61c0d5d4a 100644
--- a/libcxx/include/__algorithm/ranges_copy.h
+++ b/libcxx/include/__algorithm/ranges_copy.h
@@ -37,8 +37,7 @@ namespace ranges {
 template <class _InIter, class _OutIter>
 using copy_result = in_out_result<_InIter, _OutIter>;
 
-namespace __copy {
-struct __fn {
+struct __copy {
   template <input_iterator _InIter, sentinel_for<_InIter> _Sent, weakly_incrementable _OutIter>
     requires indirectly_copyable<_InIter, _OutIter>
   _LIBCPP_HIDE_FROM_ABI constexpr copy_result<_InIter, _OutIter>
@@ -55,10 +54,9 @@ struct __fn {
     return {std::move(__ret.first), std::move(__ret.second)};
   }
 };
-} // namespace __copy
 
 inline namespace __cpo {
-inline constexpr auto copy = __copy::__fn{};
+inline constexpr auto copy = __copy{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_copy_backward.h b/libcxx/include/__algorithm/ranges_copy_backward.h
index 93e326042503..81d14e465f7f 100644
--- a/libcxx/include/__algorithm/ranges_copy_backward.h
+++ b/libcxx/include/__algorithm/ranges_copy_backward.h
@@ -35,8 +35,7 @@ namespace ranges {
 template <class _Ip, class _Op>
 using copy_backward_result = in_out_result<_Ip, _Op>;
 
-namespace __copy_backward {
-struct __fn {
+struct __copy_backward {
   template <bidirectional_iterator _InIter1, sentinel_for<_InIter1> _Sent1, bidirectional_iterator _InIter2>
     requires indirectly_copyable<_InIter1, _InIter2>
   _LIBCPP_HIDE_FROM_ABI constexpr copy_backward_result<_InIter1, _InIter2>
@@ -53,10 +52,9 @@ struct __fn {
     return {std::move(__ret.first), std::move(__ret.second)};
   }
 };
-} // namespace __copy_backward
 
 inline namespace __cpo {
-inline constexpr auto copy_backward = __copy_backward::__fn{};
+inline constexpr auto copy_backward = __copy_backward{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_copy_if.h b/libcxx/include/__algorithm/ranges_copy_if.h
index 4b41d2154e7f..1a08985fe35c 100644
--- a/libcxx/include/__algorithm/ranges_copy_if.h
+++ b/libcxx/include/__algorithm/ranges_copy_if.h
@@ -36,8 +36,7 @@ namespace ranges {
 template <class _Ip, class _Op>
 using copy_if_result = in_out_result<_Ip, _Op>;
 
-namespace __copy_if {
-struct __fn {
+struct __copy_if {
   template <class _InIter, class _Sent, class _OutIter, class _Proj, class _Pred>
   _LIBCPP_HIDE_FROM_ABI static constexpr copy_if_result<_InIter, _OutIter>
   __copy_if_impl(_InIter __first, _Sent __last, _OutIter __result, _Pred& __pred, _Proj& __proj) {
@@ -71,10 +70,9 @@ struct __fn {
     return __copy_if_impl(ranges::begin(__r), ranges::end(__r), std::move(__result), __pred, __proj);
   }
 };
-} // namespace __copy_if
 
 inline namespace __cpo {
-inline constexpr auto copy_if = __copy_if::__fn{};
+inline constexpr auto copy_if = __copy_if{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_copy_n.h b/libcxx/include/__algorithm/ranges_copy_n.h
index 4353fa99278c..4407e07f5ca6 100644
--- a/libcxx/include/__algorithm/ranges_copy_n.h
+++ b/libcxx/include/__algorithm/ranges_copy_n.h
@@ -37,8 +37,7 @@ namespace ranges {
 template <class _Ip, class _Op>
 using copy_n_result = in_out_result<_Ip, _Op>;
 
-namespace __copy_n {
-struct __fn {
+struct __copy_n {
   template <class _InIter, class _DiffType, class _OutIter>
   _LIBCPP_HIDE_FROM_ABI constexpr static copy_n_result<_InIter, _OutIter>
   __go(_InIter __first, _DiffType __n, _OutIter __result) {
@@ -65,10 +64,9 @@ struct __fn {
     return __go(std::move(__first), __n, std::move(__result));
   }
 };
-} // namespace __copy_n
 
 inline namespace __cpo {
-inline constexpr auto copy_n = __copy_n::__fn{};
+inline constexpr auto copy_n = __copy_n{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_count.h b/libcxx/include/__algorithm/ranges_count.h
index 4f3511743870..2b3969e76307 100644
--- a/libcxx/include/__algorithm/ranges_count.h
+++ b/libcxx/include/__algorithm/ranges_count.h
@@ -34,8 +34,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __count {
-struct __fn {
+struct __count {
   template <input_iterator _Iter, sentinel_for<_Iter> _Sent, class _Type, class _Proj = identity>
     requires indirect_binary_predicate<ranges::equal_to, projected<_Iter, _Proj>, const _Type*>
   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr iter_difference_t<_Iter>
@@ -50,10 +49,9 @@ struct __fn {
     return std::__count<_RangeAlgPolicy>(ranges::begin(__r), ranges::end(__r), __value, __proj);
   }
 };
-} // namespace __count
 
 inline namespace __cpo {
-inline constexpr auto count = __count::__fn{};
+inline constexpr auto count = __count{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_count_if.h b/libcxx/include/__algorithm/ranges_count_if.h
index 5f2396ff7d53..2663180242c1 100644
--- a/libcxx/include/__algorithm/ranges_count_if.h
+++ b/libcxx/include/__algorithm/ranges_count_if.h
@@ -44,8 +44,7 @@ __count_if_impl(_Iter __first, _Sent __last, _Pred& __pred, _Proj& __proj) {
   return __counter;
 }
 
-namespace __count_if {
-struct __fn {
+struct __count_if {
   template <input_iterator _Iter,
             sentinel_for<_Iter> _Sent,
             class _Proj = identity,
@@ -63,10 +62,9 @@ struct __fn {
     return ranges::__count_if_impl(ranges::begin(__r), ranges::end(__r), __pred, __proj);
   }
 };
-} // namespace __count_if
 
 inline namespace __cpo {
-inline constexpr auto count_if = __count_if::__fn{};
+inline constexpr auto count_if = __count_if{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_ends_with.h b/libcxx/include/__algorithm/ranges_ends_with.h
index 06efdef36b7c..df7fad0bfc70 100644
--- a/libcxx/include/__algorithm/ranges_ends_with.h
+++ b/libcxx/include/__algorithm/ranges_ends_with.h
@@ -36,8 +36,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __ends_with {
-struct __fn {
+struct __ends_with {
   template <class _Iter1, class _Sent1, class _Iter2, class _Sent2, class _Pred, class _Proj1, class _Proj2>
   _LIBCPP_HIDE_FROM_ABI static constexpr bool __ends_with_fn_impl_bidirectional(
       _Iter1 __first1,
@@ -185,10 +184,9 @@ struct __fn {
     }
   }
 };
-} // namespace __ends_with
 
 inline namespace __cpo {
-inline constexpr auto ends_with = __ends_with::__fn{};
+inline constexpr auto ends_with = __ends_with{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_equal.h b/libcxx/include/__algorithm/ranges_equal.h
index edbd0e3641c1..c26d13f00220 100644
--- a/libcxx/include/__algorithm/ranges_equal.h
+++ b/libcxx/include/__algorithm/ranges_equal.h
@@ -34,8 +34,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __equal {
-struct __fn {
+struct __equal {
   template <input_iterator _Iter1,
             sentinel_for<_Iter1> _Sent1,
             input_iterator _Iter2,
@@ -93,10 +92,9 @@ struct __fn {
     return false;
   }
 };
-} // namespace __equal
 
 inline namespace __cpo {
-inline constexpr auto equal = __equal::__fn{};
+inline constexpr auto equal = __equal{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_equal_range.h b/libcxx/include/__algorithm/ranges_equal_range.h
index 4a308e016b54..cc765f196648 100644
--- a/libcxx/include/__algorithm/ranges_equal_range.h
+++ b/libcxx/include/__algorithm/ranges_equal_range.h
@@ -38,9 +38,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __equal_range {
-
-struct __fn {
+struct __equal_range {
   template <forward_iterator _Iter,
             sentinel_for<_Iter> _Sent,
             class _Tp,
@@ -64,10 +62,8 @@ struct __fn {
   }
 };
 
-} // namespace __equal_range
-
 inline namespace __cpo {
-inline constexpr auto equal_range = __equal_range::__fn{};
+inline constexpr auto equal_range = __equal_range{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_fill.h b/libcxx/include/__algorithm/ranges_fill.h
index 7a177d85e9f0..c248009f98fe 100644
--- a/libcxx/include/__algorithm/ranges_fill.h
+++ b/libcxx/include/__algorithm/ranges_fill.h
@@ -28,8 +28,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __fill {
-struct __fn {
+struct __fill {
   template <class _Type, output_iterator<const _Type&> _Iter, sentinel_for<_Iter> _Sent>
   _LIBCPP_HIDE_FROM_ABI constexpr _Iter operator()(_Iter __first, _Sent __last, const _Type& __value) const {
     if constexpr (random_access_iterator<_Iter> && sized_sentinel_for<_Sent, _Iter>) {
@@ -46,10 +45,9 @@ struct __fn {
     return (*this)(ranges::begin(__range), ranges::end(__range), __value);
   }
 };
-} // namespace __fill
 
 inline namespace __cpo {
-inline constexpr auto fill = __fill::__fn{};
+inline constexpr auto fill = __fill{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_fill_n.h b/libcxx/include/__algorithm/ranges_fill_n.h
index a6e988c0089c..7a33268e1dd3 100644
--- a/libcxx/include/__algorithm/ranges_fill_n.h
+++ b/libcxx/include/__algorithm/ranges_fill_n.h
@@ -25,8 +25,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __fill_n {
-struct __fn {
+struct __fill_n {
   template <class _Type, output_iterator<const _Type&> _Iter>
   _LIBCPP_HIDE_FROM_ABI constexpr _Iter
   operator()(_Iter __first, iter_difference_t<_Iter> __n, const _Type& __value) const {
@@ -37,10 +36,9 @@ struct __fn {
     return __first;
   }
 };
-} // namespace __fill_n
 
 inline namespace __cpo {
-inline constexpr auto fill_n = __fill_n::__fn{};
+inline constexpr auto fill_n = __fill_n{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_find.h b/libcxx/include/__algorithm/ranges_find.h
index 6b0d5efe37ab..1eac4cfa02a4 100644
--- a/libcxx/include/__algorithm/ranges_find.h
+++ b/libcxx/include/__algorithm/ranges_find.h
@@ -36,8 +36,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __find {
-struct __fn {
+struct __find {
   template <class _Iter, class _Sent, class _Tp, class _Proj>
   _LIBCPP_HIDE_FROM_ABI static constexpr _Iter
   __find_unwrap(_Iter __first, _Sent __last, const _Tp& __value, _Proj& __proj) {
@@ -64,10 +63,9 @@ struct __fn {
     return __find_unwrap(ranges::begin(__r), ranges::end(__r), __value, __proj);
   }
 };
-} // namespace __find
 
 inline namespace __cpo {
-inline constexpr auto find = __find::__fn{};
+inline constexpr auto find = __find{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_find_end.h b/libcxx/include/__algorithm/ranges_find_end.h
index e49e66dd4ac0..682724a48cd5 100644
--- a/libcxx/include/__algorithm/ranges_find_end.h
+++ b/libcxx/include/__algorithm/ranges_find_end.h
@@ -35,8 +35,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __find_end {
-struct __fn {
+struct __find_end {
   template <forward_iterator _Iter1,
             sentinel_for<_Iter1> _Sent1,
             forward_iterator _Iter2,
@@ -87,10 +86,9 @@ struct __fn {
     return {__ret.first, __ret.second};
   }
 };
-} // namespace __find_end
 
 inline namespace __cpo {
-inline constexpr auto find_end = __find_end::__fn{};
+inline constexpr auto find_end = __find_end{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_find_first_of.h b/libcxx/include/__algorithm/ranges_find_first_of.h
index d92d9686bc44..102e16dd7a55 100644
--- a/libcxx/include/__algorithm/ranges_find_first_of.h
+++ b/libcxx/include/__algorithm/ranges_find_first_of.h
@@ -32,8 +32,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __find_first_of {
-struct __fn {
+struct __find_first_of {
   template <class _Iter1, class _Sent1, class _Iter2, class _Sent2, class _Pred, class _Proj1, class _Proj2>
   _LIBCPP_HIDE_FROM_ABI constexpr static _Iter1 __find_first_of_impl(
       _Iter1 __first1,
@@ -90,10 +89,9 @@ struct __fn {
         __proj2);
   }
 };
-} // namespace __find_first_of
 
 inline namespace __cpo {
-inline constexpr auto find_first_of = __find_first_of::__fn{};
+inline constexpr auto find_first_of = __find_first_of{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_find_if.h b/libcxx/include/__algorithm/ranges_find_if.h
index 888f9ec3cb2d..ed6406e6186a 100644
--- a/libcxx/include/__algorithm/ranges_find_if.h
+++ b/libcxx/include/__algorithm/ranges_find_if.h
@@ -42,8 +42,7 @@ _LIBCPP_HIDE_FROM_ABI constexpr _Ip __find_if_impl(_Ip __first, _Sp __last, _Pre
   return __first;
 }
 
-namespace __find_if {
-struct __fn {
+struct __find_if {
   template <input_iterator _Ip,
             sentinel_for<_Ip> _Sp,
             class _Proj = identity,
@@ -59,10 +58,9 @@ struct __fn {
     return ranges::__find_if_impl(ranges::begin(__r), ranges::end(__r), __pred, __proj);
   }
 };
-} // namespace __find_if
 
 inline namespace __cpo {
-inline constexpr auto find_if = __find_if::__fn{};
+inline constexpr auto find_if = __find_if{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_find_if_not.h b/libcxx/include/__algorithm/ranges_find_if_not.h
index ec19545b5a1b..9a359b2afdab 100644
--- a/libcxx/include/__algorithm/ranges_find_if_not.h
+++ b/libcxx/include/__algorithm/ranges_find_if_not.h
@@ -34,8 +34,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __find_if_not {
-struct __fn {
+struct __find_if_not {
   template <input_iterator _Ip,
             sentinel_for<_Ip> _Sp,
             class _Proj = identity,
@@ -53,10 +52,9 @@ struct __fn {
     return ranges::__find_if_impl(ranges::begin(__r), ranges::end(__r), __pred2, __proj);
   }
 };
-} // namespace __find_if_not
 
 inline namespace __cpo {
-inline constexpr auto find_if_not = __find_if_not::__fn{};
+inline constexpr auto find_if_not = __find_if_not{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_find_last.h b/libcxx/include/__algorithm/ranges_find_last.h
index 95f7e77b8ccb..838dd44e5d10 100644
--- a/libcxx/include/__algorithm/ranges_find_last.h
+++ b/libcxx/include/__algorithm/ranges_find_last.h
@@ -72,8 +72,7 @@ __find_last_impl(_Iter __first, _Sent __last, _Pred __pred, _Proj& __proj) {
   }
 }
 
-namespace __find_last {
-struct __fn {
+struct __find_last {
   template <class _Type>
   struct __op {
     const _Type& __value;
@@ -97,10 +96,8 @@ struct __fn {
     return ranges::__find_last_impl(ranges::begin(__range), ranges::end(__range), __op<_Type>{__value}, __proj);
   }
 };
-} // namespace __find_last
 
-namespace __find_last_if {
-struct __fn {
+struct __find_last_if {
   template <class _Pred>
   struct __op {
     _Pred& __pred;
@@ -127,10 +124,8 @@ struct __fn {
     return ranges::__find_last_impl(ranges::begin(__range), ranges::end(__range), __op<_Pred>{__pred}, __proj);
   }
 };
-} // namespace __find_last_if
 
-namespace __find_last_if_not {
-struct __fn {
+struct __find_last_if_not {
   template <class _Pred>
   struct __op {
     _Pred& __pred;
@@ -157,12 +152,11 @@ struct __fn {
     return ranges::__find_last_impl(ranges::begin(__range), ranges::end(__range), __op<_Pred>{__pred}, __proj);
   }
 };
-} // namespace __find_last_if_not
 
 inline namespace __cpo {
-inline constexpr auto find_last        = __find_last::__fn{};
-inline constexpr auto find_last_if     = __find_last_if::__fn{};
-inline constexpr auto find_last_if_not = __find_last_if_not::__fn{};
+inline constexpr auto find_last        = __find_last{};
+inline constexpr auto find_last_if     = __find_last_if{};
+inline constexpr auto find_last_if_not = __find_last_if_not{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_for_each.h b/libcxx/include/__algorithm/ranges_for_each.h
index 225dc774c876..de39bc552275 100644
--- a/libcxx/include/__algorithm/ranges_for_each.h
+++ b/libcxx/include/__algorithm/ranges_for_each.h
@@ -36,8 +36,7 @@ namespace ranges {
 template <class _Iter, class _Func>
 using for_each_result = in_fun_result<_Iter, _Func>;
 
-namespace __for_each {
-struct __fn {
+struct __for_each {
 private:
   template <class _Iter, class _Sent, class _Proj, class _Func>
   _LIBCPP_HIDE_FROM_ABI constexpr static for_each_result<_Iter, _Func>
@@ -65,10 +64,9 @@ public:
     return __for_each_impl(ranges::begin(__range), ranges::end(__range), __func, __proj);
   }
 };
-} // namespace __for_each
 
 inline namespace __cpo {
-inline constexpr auto for_each = __for_each::__fn{};
+inline constexpr auto for_each = __for_each{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_for_each_n.h b/libcxx/include/__algorithm/ranges_for_each_n.h
index d1fdca34cc5a..603cb723233c 100644
--- a/libcxx/include/__algorithm/ranges_for_each_n.h
+++ b/libcxx/include/__algorithm/ranges_for_each_n.h
@@ -36,8 +36,7 @@ namespace ranges {
 template <class _Iter, class _Func>
 using for_each_n_result = in_fun_result<_Iter, _Func>;
 
-namespace __for_each_n {
-struct __fn {
+struct __for_each_n {
   template <input_iterator _Iter, class _Proj = identity, indirectly_unary_invocable<projected<_Iter, _Proj>> _Func>
   _LIBCPP_HIDE_FROM_ABI constexpr for_each_n_result<_Iter, _Func>
   operator()(_Iter __first, iter_difference_t<_Iter> __count, _Func __func, _Proj __proj = {}) const {
@@ -48,10 +47,9 @@ struct __fn {
     return {std::move(__first), std::move(__func)};
   }
 };
-} // namespace __for_each_n
 
 inline namespace __cpo {
-inline constexpr auto for_each_n = __for_each_n::__fn{};
+inline constexpr auto for_each_n = __for_each_n{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_generate.h b/libcxx/include/__algorithm/ranges_generate.h
index e6467198e6ba..b94611d18263 100644
--- a/libcxx/include/__algorithm/ranges_generate.h
+++ b/libcxx/include/__algorithm/ranges_generate.h
@@ -32,9 +32,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __generate {
-
-struct __fn {
+struct __generate {
   template <class _OutIter, class _Sent, class _Func>
   _LIBCPP_HIDE_FROM_ABI constexpr static _OutIter __generate_fn_impl(_OutIter __first, _Sent __last, _Func& __gen) {
     for (; __first != __last; ++__first) {
@@ -57,10 +55,8 @@ struct __fn {
   }
 };
 
-} // namespace __generate
-
 inline namespace __cpo {
-inline constexpr auto generate = __generate::__fn{};
+inline constexpr auto generate = __generate{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_generate_n.h b/libcxx/include/__algorithm/ranges_generate_n.h
index cd5fd7483ab2..702e9a949cb4 100644
--- a/libcxx/include/__algorithm/ranges_generate_n.h
+++ b/libcxx/include/__algorithm/ranges_generate_n.h
@@ -33,9 +33,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __generate_n {
-
-struct __fn {
+struct __generate_n {
   template <input_or_output_iterator _OutIter, copy_constructible _Func>
     requires invocable<_Func&> && indirectly_writable<_OutIter, invoke_result_t<_Func&>>
   _LIBCPP_HIDE_FROM_ABI constexpr _OutIter
@@ -49,10 +47,8 @@ struct __fn {
   }
 };
 
-} // namespace __generate_n
-
 inline namespace __cpo {
-inline constexpr auto generate_n = __generate_n::__fn{};
+inline constexpr auto generate_n = __generate_n{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_includes.h b/libcxx/include/__algorithm/ranges_includes.h
index c4c3b8ed088d..9145f3b5564f 100644
--- a/libcxx/include/__algorithm/ranges_includes.h
+++ b/libcxx/include/__algorithm/ranges_includes.h
@@ -35,9 +35,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __includes {
-
-struct __fn {
+struct __includes {
   template <input_iterator _Iter1,
             sentinel_for<_Iter1> _Sent1,
             input_iterator _Iter2,
@@ -82,10 +80,8 @@ struct __fn {
   }
 };
 
-} // namespace __includes
-
 inline namespace __cpo {
-inline constexpr auto includes = __includes::__fn{};
+inline constexpr auto includes = __includes{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_inplace_merge.h b/libcxx/include/__algorithm/ranges_inplace_merge.h
index d94c0ad46567..5879d0e7ef0f 100644
--- a/libcxx/include/__algorithm/ranges_inplace_merge.h
+++ b/libcxx/include/__algorithm/ranges_inplace_merge.h
@@ -39,9 +39,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __inplace_merge {
-
-struct __fn {
+struct __inplace_merge {
   template <class _Iter, class _Sent, class _Comp, class _Proj>
   _LIBCPP_HIDE_FROM_ABI static constexpr auto
   __inplace_merge_impl(_Iter __first, _Iter __middle, _Sent __last, _Comp&& __comp, _Proj&& __proj) {
@@ -68,10 +66,8 @@ struct __fn {
   }
 };
 
-} // namespace __inplace_merge
-
 inline namespace __cpo {
-inline constexpr auto inplace_merge = __inplace_merge::__fn{};
+inline constexpr auto inplace_merge = __inplace_merge{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_is_heap.h b/libcxx/include/__algorithm/ranges_is_heap.h
index 3d9e18ce1d90..b4724abfb62a 100644
--- a/libcxx/include/__algorithm/ranges_is_heap.h
+++ b/libcxx/include/__algorithm/ranges_is_heap.h
@@ -34,9 +34,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __is_heap {
-
-struct __fn {
+struct __is_heap {
   template <class _Iter, class _Sent, class _Proj, class _Comp>
   _LIBCPP_HIDE_FROM_ABI constexpr static bool
   __is_heap_fn_impl(_Iter __first, _Sent __last, _Comp& __comp, _Proj& __proj) {
@@ -65,10 +63,8 @@ struct __fn {
   }
 };
 
-} // namespace __is_heap
-
 inline namespace __cpo {
-inline constexpr auto is_heap = __is_heap::__fn{};
+inline constexpr auto is_heap = __is_heap{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_is_heap_until.h b/libcxx/include/__algorithm/ranges_is_heap_until.h
index 7a2e1fc7705b..25f3b484faa6 100644
--- a/libcxx/include/__algorithm/ranges_is_heap_until.h
+++ b/libcxx/include/__algorithm/ranges_is_heap_until.h
@@ -35,9 +35,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __is_heap_until {
-
-struct __fn {
+struct __is_heap_until {
   template <class _Iter, class _Sent, class _Proj, class _Comp>
   _LIBCPP_HIDE_FROM_ABI constexpr static _Iter
   __is_heap_until_fn_impl(_Iter __first, _Sent __last, _Comp& __comp, _Proj& __proj) {
@@ -65,10 +63,8 @@ struct __fn {
   }
 };
 
-} // namespace __is_heap_until
-
 inline namespace __cpo {
-inline constexpr auto is_heap_until = __is_heap_until::__fn{};
+inline constexpr auto is_heap_until = __is_heap_until{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_is_partitioned.h b/libcxx/include/__algorithm/ranges_is_partitioned.h
index 5be6fba46fd9..8092abfcd1de 100644
--- a/libcxx/include/__algorithm/ranges_is_partitioned.h
+++ b/libcxx/include/__algorithm/ranges_is_partitioned.h
@@ -31,8 +31,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __is_partitioned {
-struct __fn {
+struct __is_partitioned {
   template <class _Iter, class _Sent, class _Proj, class _Pred>
   _LIBCPP_HIDE_FROM_ABI constexpr static bool
   __is_partitioned_impl(_Iter __first, _Sent __last, _Pred& __pred, _Proj& __proj) {
@@ -70,10 +69,9 @@ struct __fn {
     return __is_partitioned_impl(ranges::begin(__range), ranges::end(__range), __pred, __proj);
   }
 };
-} // namespace __is_partitioned
 
 inline namespace __cpo {
-inline constexpr auto is_partitioned = __is_partitioned::__fn{};
+inline constexpr auto is_partitioned = __is_partitioned{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_is_permutation.h b/libcxx/include/__algorithm/ranges_is_permutation.h
index 1f8d67007a57..53a431d2ba42 100644
--- a/libcxx/include/__algorithm/ranges_is_permutation.h
+++ b/libcxx/include/__algorithm/ranges_is_permutation.h
@@ -33,8 +33,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __is_permutation {
-struct __fn {
+struct __is_permutation {
   template <class _Iter1, class _Sent1, class _Iter2, class _Sent2, class _Proj1, class _Proj2, class _Pred>
   _LIBCPP_HIDE_FROM_ABI constexpr static bool __is_permutation_func_impl(
       _Iter1 __first1,
@@ -91,10 +90,9 @@ struct __fn {
         __proj2);
   }
 };
-} // namespace __is_permutation
 
 inline namespace __cpo {
-inline constexpr auto is_permutation = __is_permutation::__fn{};
+inline constexpr auto is_permutation = __is_permutation{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_is_sorted.h b/libcxx/include/__algorithm/ranges_is_sorted.h
index 5b88d422b4b0..ab0670688a0e 100644
--- a/libcxx/include/__algorithm/ranges_is_sorted.h
+++ b/libcxx/include/__algorithm/ranges_is_sorted.h
@@ -31,8 +31,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __is_sorted {
-struct __fn {
+struct __is_sorted {
   template <forward_iterator _Iter,
             sentinel_for<_Iter> _Sent,
             class _Proj                                               = identity,
@@ -51,10 +50,9 @@ struct __fn {
     return ranges::__is_sorted_until_impl(ranges::begin(__range), __last, __comp, __proj) == __last;
   }
 };
-} // namespace __is_sorted
 
 inline namespace __cpo {
-inline constexpr auto is_sorted = __is_sorted::__fn{};
+inline constexpr auto is_sorted = __is_sorted{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_is_sorted_until.h b/libcxx/include/__algorithm/ranges_is_sorted_until.h
index 54de530c8b2f..f2e51c264e4a 100644
--- a/libcxx/include/__algorithm/ranges_is_sorted_until.h
+++ b/libcxx/include/__algorithm/ranges_is_sorted_until.h
@@ -47,8 +47,7 @@ __is_sorted_until_impl(_Iter __first, _Sent __last, _Comp& __comp, _Proj& __proj
   return __i;
 }
 
-namespace __is_sorted_until {
-struct __fn {
+struct __is_sorted_until {
   template <forward_iterator _Iter,
             sentinel_for<_Iter> _Sent,
             class _Proj                                               = identity,
@@ -66,10 +65,9 @@ struct __fn {
     return ranges::__is_sorted_until_impl(ranges::begin(__range), ranges::end(__range), __comp, __proj);
   }
 };
-} // namespace __is_sorted_until
 
 inline namespace __cpo {
-inline constexpr auto is_sorted_until = __is_sorted_until::__fn{};
+inline constexpr auto is_sorted_until = __is_sorted_until{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_lexicographical_compare.h b/libcxx/include/__algorithm/ranges_lexicographical_compare.h
index 6d82017e302a..024cc6b707ca 100644
--- a/libcxx/include/__algorithm/ranges_lexicographical_compare.h
+++ b/libcxx/include/__algorithm/ranges_lexicographical_compare.h
@@ -31,8 +31,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __lexicographical_compare {
-struct __fn {
+struct __lexicographical_compare {
   template <class _Iter1, class _Sent1, class _Iter2, class _Sent2, class _Proj1, class _Proj2, class _Comp>
   _LIBCPP_HIDE_FROM_ABI constexpr static bool __lexicographical_compare_impl(
       _Iter1 __first1,
@@ -90,10 +89,9 @@ struct __fn {
         __proj2);
   }
 };
-} // namespace __lexicographical_compare
 
 inline namespace __cpo {
-inline constexpr auto lexicographical_compare = __lexicographical_compare::__fn{};
+inline constexpr auto lexicographical_compare = __lexicographical_compare{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_lower_bound.h b/libcxx/include/__algorithm/ranges_lower_bound.h
index 0651147e0424..d1b332849b8b 100644
--- a/libcxx/include/__algorithm/ranges_lower_bound.h
+++ b/libcxx/include/__algorithm/ranges_lower_bound.h
@@ -36,8 +36,7 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
 
-namespace __lower_bound {
-struct __fn {
+struct __lower_bound {
   template <forward_iterator _Iter,
             sentinel_for<_Iter> _Sent,
             class _Type,
@@ -57,10 +56,9 @@ struct __fn {
     return std::__lower_bound<_RangeAlgPolicy>(ranges::begin(__r), ranges::end(__r), __value, __comp, __proj);
   }
 };
-} // namespace __lower_bound
 
 inline namespace __cpo {
-inline constexpr auto lower_bound = __lower_bound::__fn{};
+inline constexpr auto lower_bound = __lower_bound{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_make_heap.h b/libcxx/include/__algorithm/ranges_make_heap.h
index fe9c024fbf8a..97148f77b418 100644
--- a/libcxx/include/__algorithm/ranges_make_heap.h
+++ b/libcxx/include/__algorithm/ranges_make_heap.h
@@ -40,9 +40,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __make_heap {
-
-struct __fn {
+struct __make_heap {
   template <class _Iter, class _Sent, class _Comp, class _Proj>
   _LIBCPP_HIDE_FROM_ABI constexpr static _Iter
   __make_heap_fn_impl(_Iter __first, _Sent __last, _Comp& __comp, _Proj& __proj) {
@@ -69,10 +67,8 @@ struct __fn {
   }
 };
 
-} // namespace __make_heap
-
 inline namespace __cpo {
-inline constexpr auto make_heap = __make_heap::__fn{};
+inline constexpr auto make_heap = __make_heap{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_max.h b/libcxx/include/__algorithm/ranges_max.h
index d0ee6f314b0c..f631344422ed 100644
--- a/libcxx/include/__algorithm/ranges_max.h
+++ b/libcxx/include/__algorithm/ranges_max.h
@@ -36,8 +36,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __max {
-struct __fn {
+struct __max {
   template <class _Tp,
             class _Proj                                                    = identity,
             indirect_strict_weak_order<projected<const _Tp*, _Proj>> _Comp = ranges::less>
@@ -87,10 +86,9 @@ struct __fn {
     }
   }
 };
-} // namespace __max
 
 inline namespace __cpo {
-inline constexpr auto max = __max::__fn{};
+inline constexpr auto max = __max{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_max_element.h b/libcxx/include/__algorithm/ranges_max_element.h
index c57730927116..869f71ecc8d2 100644
--- a/libcxx/include/__algorithm/ranges_max_element.h
+++ b/libcxx/include/__algorithm/ranges_max_element.h
@@ -32,8 +32,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __max_element {
-struct __fn {
+struct __max_element {
   template <forward_iterator _Ip,
             sentinel_for<_Ip> _Sp,
             class _Proj                                             = identity,
@@ -53,10 +52,9 @@ struct __fn {
     return ranges::__min_element_impl(ranges::begin(__r), ranges::end(__r), __comp_lhs_rhs_swapped, __proj);
   }
 };
-} // namespace __max_element
 
 inline namespace __cpo {
-inline constexpr auto max_element = __max_element::__fn{};
+inline constexpr auto max_element = __max_element{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_merge.h b/libcxx/include/__algorithm/ranges_merge.h
index bdf9a62d90bd..f3e0486fe488 100644
--- a/libcxx/include/__algorithm/ranges_merge.h
+++ b/libcxx/include/__algorithm/ranges_merge.h
@@ -39,42 +39,7 @@ namespace ranges {
 template <class _InIter1, class _InIter2, class _OutIter>
 using merge_result = in_in_out_result<_InIter1, _InIter2, _OutIter>;
 
-namespace __merge {
-
-template < class _InIter1,
-           class _Sent1,
-           class _InIter2,
-           class _Sent2,
-           class _OutIter,
-           class _Comp,
-           class _Proj1,
-           class _Proj2>
-_LIBCPP_HIDE_FROM_ABI constexpr merge_result<__remove_cvref_t<_InIter1>,
-                                             __remove_cvref_t<_InIter2>,
-                                             __remove_cvref_t<_OutIter>>
-__merge_impl(_InIter1&& __first1,
-             _Sent1&& __last1,
-             _InIter2&& __first2,
-             _Sent2&& __last2,
-             _OutIter&& __result,
-             _Comp&& __comp,
-             _Proj1&& __proj1,
-             _Proj2&& __proj2) {
-  for (; __first1 != __last1 && __first2 != __last2; ++__result) {
-    if (std::invoke(__comp, std::invoke(__proj2, *__first2), std::invoke(__proj1, *__first1))) {
-      *__result = *__first2;
-      ++__first2;
-    } else {
-      *__result = *__first1;
-      ++__first1;
-    }
-  }
-  auto __ret1 = ranges::copy(std::move(__first1), std::move(__last1), std::move(__result));
-  auto __ret2 = ranges::copy(std::move(__first2), std::move(__last2), std::move(__ret1.out));
-  return {std::move(__ret1.in), std::move(__ret2.in), std::move(__ret2.out)};
-}
-
-struct __fn {
+struct __merge {
   template <input_iterator _InIter1,
             sentinel_for<_InIter1> _Sent1,
             input_iterator _InIter2,
@@ -120,12 +85,43 @@ struct __fn {
         __proj1,
         __proj2);
   }
+
+  template < class _InIter1,
+             class _Sent1,
+             class _InIter2,
+             class _Sent2,
+             class _OutIter,
+             class _Comp,
+             class _Proj1,
+             class _Proj2>
+  _LIBCPP_HIDE_FROM_ABI static constexpr merge_result<__remove_cvref_t<_InIter1>,
+                                                      __remove_cvref_t<_InIter2>,
+                                                      __remove_cvref_t<_OutIter>>
+  __merge_impl(_InIter1&& __first1,
+               _Sent1&& __last1,
+               _InIter2&& __first2,
+               _Sent2&& __last2,
+               _OutIter&& __result,
+               _Comp&& __comp,
+               _Proj1&& __proj1,
+               _Proj2&& __proj2) {
+    for (; __first1 != __last1 && __first2 != __last2; ++__result) {
+      if (std::invoke(__comp, std::invoke(__proj2, *__first2), std::invoke(__proj1, *__first1))) {
+        *__result = *__first2;
+        ++__first2;
+      } else {
+        *__result = *__first1;
+        ++__first1;
+      }
+    }
+    auto __ret1 = ranges::copy(std::move(__first1), std::move(__last1), std::move(__result));
+    auto __ret2 = ranges::copy(std::move(__first2), std::move(__last2), std::move(__ret1.out));
+    return {std::move(__ret1.in), std::move(__ret2.in), std::move(__ret2.out)};
+  }
 };
 
-} // namespace __merge
-
 inline namespace __cpo {
-inline constexpr auto merge = __merge::__fn{};
+inline constexpr auto merge = __merge{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_min.h b/libcxx/include/__algorithm/ranges_min.h
index cc569d2a060c..302b5d7975b0 100644
--- a/libcxx/include/__algorithm/ranges_min.h
+++ b/libcxx/include/__algorithm/ranges_min.h
@@ -35,8 +35,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __min {
-struct __fn {
+struct __min {
   template <class _Tp,
             class _Proj                                                    = identity,
             indirect_strict_weak_order<projected<const _Tp*, _Proj>> _Comp = ranges::less>
@@ -79,10 +78,9 @@ struct __fn {
     }
   }
 };
-} // namespace __min
 
 inline namespace __cpo {
-inline constexpr auto min = __min::__fn{};
+inline constexpr auto min = __min{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_min_element.h b/libcxx/include/__algorithm/ranges_min_element.h
index 588ef258e26f..fb92ae56bcd6 100644
--- a/libcxx/include/__algorithm/ranges_min_element.h
+++ b/libcxx/include/__algorithm/ranges_min_element.h
@@ -46,8 +46,7 @@ _LIBCPP_HIDE_FROM_ABI constexpr _Ip __min_element_impl(_Ip __first, _Sp __last,
   return __first;
 }
 
-namespace __min_element {
-struct __fn {
+struct __min_element {
   template <forward_iterator _Ip,
             sentinel_for<_Ip> _Sp,
             class _Proj                                             = identity,
@@ -65,10 +64,9 @@ struct __fn {
     return ranges::__min_element_impl(ranges::begin(__r), ranges::end(__r), __comp, __proj);
   }
 };
-} // namespace __min_element
 
 inline namespace __cpo {
-inline constexpr auto min_element = __min_element::__fn{};
+inline constexpr auto min_element = __min_element{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_minmax.h b/libcxx/include/__algorithm/ranges_minmax.h
index 09cbefd91a8c..1b43b1e19cde 100644
--- a/libcxx/include/__algorithm/ranges_minmax.h
+++ b/libcxx/include/__algorithm/ranges_minmax.h
@@ -47,8 +47,7 @@ namespace ranges {
 template <class _T1>
 using minmax_result = min_max_result<_T1>;
 
-namespace __minmax {
-struct __fn {
+struct __minmax {
   template <class _Type,
             class _Proj                                                      = identity,
             indirect_strict_weak_order<projected<const _Type*, _Proj>> _Comp = ranges::less>
@@ -159,10 +158,9 @@ struct __fn {
     }
   }
 };
-} // namespace __minmax
 
 inline namespace __cpo {
-inline constexpr auto minmax = __minmax::__fn{};
+inline constexpr auto minmax = __minmax{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_minmax_element.h b/libcxx/include/__algorithm/ranges_minmax_element.h
index 4bf6d2404e46..e1a22dde0955 100644
--- a/libcxx/include/__algorithm/ranges_minmax_element.h
+++ b/libcxx/include/__algorithm/ranges_minmax_element.h
@@ -40,8 +40,7 @@ namespace ranges {
 template <class _T1>
 using minmax_element_result = min_max_result<_T1>;
 
-namespace __minmax_element {
-struct __fn {
+struct __minmax_element {
   template <forward_iterator _Ip,
             sentinel_for<_Ip> _Sp,
             class _Proj                                             = identity,
@@ -61,10 +60,9 @@ struct __fn {
     return {__ret.first, __ret.second};
   }
 };
-} // namespace __minmax_element
 
 inline namespace __cpo {
-inline constexpr auto minmax_element = __minmax_element::__fn{};
+inline constexpr auto minmax_element = __minmax_element{};
 } // namespace __cpo
 
 } // namespace ranges
diff --git a/libcxx/include/__algorithm/ranges_mismatch.h b/libcxx/include/__algorithm/ranges_mismatch.h
index c4bf0022a9bc..b35747dfa43a 100644
--- a/libcxx/include/__algorithm/ranges_mismatch.h
+++ b/libcxx/include/__algorithm/ranges_mismatch.h
@@ -39,8 +39,7 @@ namespace ranges {
 template <class _I1, class _I2>
 using mismatch_result = in_in_result<_I1, _I2>;
 
-namespace __mismatch {
-struct __fn {
+struct __mismatch {
   template <class _I1, class _S1, class _I2, class _S2, class _Pred, class _Proj1, class _Proj2>
   static _LIBCPP_HIDE_FROM_ABI constexpr mismatch_result<_I1, _I2>
   __go(_I1 __first1, _S1 __last1, _I2 __first2, _S2 __last2, _Pred& __pred, _Proj1& __proj1, _Proj2& __proj2) {
@@ -84,10 +83,9 @@ struct __fn {
         ranges::begin(__r1), ranges::end(__r1), ranges::begin(__r2), ranges::end(__r2), __pred, __proj1, __proj2);
   }
 };
-} // namespace __mismatch
 
 inline namespace __cpo {
-constexpr inline auto mismatch = __mismatch::__fn{};
+constexpr inline auto mismatch = __mismatch{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_move.h b/libcxx/include/__algorithm/ranges_move.h
index be869f36c973..02bf7fd00619 100644
--- a/libcxx/include/__algorithm/ranges_move.h
+++ b/libcxx/include/__algorithm/ranges_move.h
@@ -35,8 +35,7 @@ namespace ranges {
 template <class _InIter, class _OutIter>
 using move_result = in_out_result<_InIter, _OutIter>;
 
-namespace __move {
-struct __fn {
+struct __move {
   template <class _InIter, class _Sent, class _OutIter>
   _LIBCPP_HIDE_FROM_ABI constexpr static move_result<_InIter, _OutIter>
   __move_impl(_InIter __first, _Sent __last, _OutIter __result) {
@@ -58,10 +57,9 @@ struct __fn {
     return __move_impl(ranges::begin(__range), ranges::end(__range), std::move(__result));
   }
 };
-} // namespace __move
 
 inline namespace __cpo {
-inline constexpr auto move = __move::__fn{};
+inline constexpr auto move = __move{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_move_backward.h b/libcxx/include/__algorithm/ranges_move_backward.h
index 6d4071a33b81..4737e6c9756d 100644
--- a/libcxx/include/__algorithm/ranges_move_backward.h
+++ b/libcxx/include/__algorithm/ranges_move_backward.h
@@ -37,8 +37,7 @@ namespace ranges {
 template <class _InIter, class _OutIter>
 using move_backward_result = in_out_result<_InIter, _OutIter>;
 
-namespace __move_backward {
-struct __fn {
+struct __move_backward {
   template <class _InIter, class _Sent, class _OutIter>
   _LIBCPP_HIDE_FROM_ABI constexpr static move_backward_result<_InIter, _OutIter>
   __move_backward_impl(_InIter __first, _Sent __last, _OutIter __result) {
@@ -60,10 +59,9 @@ struct __fn {
     return __move_backward_impl(ranges::begin(__range), ranges::end(__range), std::move(__result));
   }
 };
-} // namespace __move_backward
 
 inline namespace __cpo {
-inline constexpr auto move_backward = __move_backward::__fn{};
+inline constexpr auto move_backward = __move_backward{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_next_permutation.h b/libcxx/include/__algorithm/ranges_next_permutation.h
index 18535e0a6254..1b485423e892 100644
--- a/libcxx/include/__algorithm/ranges_next_permutation.h
+++ b/libcxx/include/__algorithm/ranges_next_permutation.h
@@ -40,9 +40,7 @@ namespace ranges {
 template <class _InIter>
 using next_permutation_result = in_found_result<_InIter>;
 
-namespace __next_permutation {
-
-struct __fn {
+struct __next_permutation {
   template <bidirectional_iterator _Iter, sentinel_for<_Iter> _Sent, class _Comp = ranges::less, class _Proj = identity>
     requires sortable<_Iter, _Comp, _Proj>
   _LIBCPP_HIDE_FROM_ABI constexpr next_permutation_result<_Iter>
@@ -62,10 +60,8 @@ struct __fn {
   }
 };
 
-} // namespace __next_permutation
-
 inline namespace __cpo {
-constexpr inline auto next_permutation = __next_permutation::__fn{};
+constexpr inline auto next_permutation = __next_permutation{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_none_of.h b/libcxx/include/__algorithm/ranges_none_of.h
index 7df3c1829fcf..a1612826220d 100644
--- a/libcxx/include/__algorithm/ranges_none_of.h
+++ b/libcxx/include/__algorithm/ranges_none_of.h
@@ -30,8 +30,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __none_of {
-struct __fn {
+struct __none_of {
   template <class _Iter, class _Sent, class _Proj, class _Pred>
   _LIBCPP_HIDE_FROM_ABI constexpr static bool
   __none_of_impl(_Iter __first, _Sent __last, _Pred& __pred, _Proj& __proj) {
@@ -59,10 +58,9 @@ struct __fn {
     return __none_of_impl(ranges::begin(__range), ranges::end(__range), __pred, __proj);
   }
 };
-} // namespace __none_of
 
 inline namespace __cpo {
-inline constexpr auto none_of = __none_of::__fn{};
+inline constexpr auto none_of = __none_of{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_nth_element.h b/libcxx/include/__algorithm/ranges_nth_element.h
index 90ade9efe10d..e92c51e713cb 100644
--- a/libcxx/include/__algorithm/ranges_nth_element.h
+++ b/libcxx/include/__algorithm/ranges_nth_element.h
@@ -39,9 +39,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __nth_element {
-
-struct __fn {
+struct __nth_element {
   template <class _Iter, class _Sent, class _Comp, class _Proj>
   _LIBCPP_HIDE_FROM_ABI constexpr static _Iter
   __nth_element_fn_impl(_Iter __first, _Iter __nth, _Sent __last, _Comp& __comp, _Proj& __proj) {
@@ -68,10 +66,8 @@ struct __fn {
   }
 };
 
-} // namespace __nth_element
-
 inline namespace __cpo {
-inline constexpr auto nth_element = __nth_element::__fn{};
+inline constexpr auto nth_element = __nth_element{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_partial_sort.h b/libcxx/include/__algorithm/ranges_partial_sort.h
index c67247d2e0a7..fc8a1f7d9306 100644
--- a/libcxx/include/__algorithm/ranges_partial_sort.h
+++ b/libcxx/include/__algorithm/ranges_partial_sort.h
@@ -41,9 +41,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __partial_sort {
-
-struct __fn {
+struct __partial_sort {
   template <class _Iter, class _Sent, class _Comp, class _Proj>
   _LIBCPP_HIDE_FROM_ABI constexpr static _Iter
   __partial_sort_fn_impl(_Iter __first, _Iter __middle, _Sent __last, _Comp& __comp, _Proj& __proj) {
@@ -66,10 +64,8 @@ struct __fn {
   }
 };
 
-} // namespace __partial_sort
-
 inline namespace __cpo {
-inline constexpr auto partial_sort = __partial_sort::__fn{};
+inline constexpr auto partial_sort = __partial_sort{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_partial_sort_copy.h b/libcxx/include/__algorithm/ranges_partial_sort_copy.h
index b3bdeb78fb6f..f221504a8cae 100644
--- a/libcxx/include/__algorithm/ranges_partial_sort_copy.h
+++ b/libcxx/include/__algorithm/ranges_partial_sort_copy.h
@@ -42,9 +42,7 @@ namespace ranges {
 template <class _InIter, class _OutIter>
 using partial_sort_copy_result = in_out_result<_InIter, _OutIter>;
 
-namespace __partial_sort_copy {
-
-struct __fn {
+struct __partial_sort_copy {
   template <input_iterator _Iter1,
             sentinel_for<_Iter1> _Sent1,
             random_access_iterator _Iter2,
@@ -98,10 +96,8 @@ struct __fn {
   }
 };
 
-} // namespace __partial_sort_copy
-
 inline namespace __cpo {
-inline constexpr auto partial_sort_copy = __partial_sort_copy::__fn{};
+inline constexpr auto partial_sort_copy = __partial_sort_copy{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_partition.h b/libcxx/include/__algorithm/ranges_partition.h
index a67ac4c96757..7058cb0c3969 100644
--- a/libcxx/include/__algorithm/ranges_partition.h
+++ b/libcxx/include/__algorithm/ranges_partition.h
@@ -40,9 +40,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __partition {
-
-struct __fn {
+struct __partition {
   template <class _Iter, class _Sent, class _Proj, class _Pred>
   _LIBCPP_HIDE_FROM_ABI static constexpr subrange<__remove_cvref_t<_Iter>>
   __partition_fn_impl(_Iter&& __first, _Sent&& __last, _Pred&& __pred, _Proj&& __proj) {
@@ -72,10 +70,8 @@ struct __fn {
   }
 };
 
-} // namespace __partition
-
 inline namespace __cpo {
-inline constexpr auto partition = __partition::__fn{};
+inline constexpr auto partition = __partition{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_partition_copy.h b/libcxx/include/__algorithm/ranges_partition_copy.h
index d60c865dd2a8..47878a401723 100644
--- a/libcxx/include/__algorithm/ranges_partition_copy.h
+++ b/libcxx/include/__algorithm/ranges_partition_copy.h
@@ -38,9 +38,7 @@ namespace ranges {
 template <class _InIter, class _OutIter1, class _OutIter2>
 using partition_copy_result = in_out_out_result<_InIter, _OutIter1, _OutIter2>;
 
-namespace __partition_copy {
-
-struct __fn {
+struct __partition_copy {
   // TODO(ranges): delegate to the classic algorithm.
   template <class _InIter, class _Sent, class _OutIter1, class _OutIter2, class _Proj, class _Pred>
   _LIBCPP_HIDE_FROM_ABI constexpr static partition_copy_result<__remove_cvref_t<_InIter>,
@@ -94,10 +92,8 @@ struct __fn {
   }
 };
 
-} // namespace __partition_copy
-
 inline namespace __cpo {
-inline constexpr auto partition_copy = __partition_copy::__fn{};
+inline constexpr auto partition_copy = __partition_copy{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_partition_point.h b/libcxx/include/__algorithm/ranges_partition_point.h
index c5b11b5fed19..324efbb86d64 100644
--- a/libcxx/include/__algorithm/ranges_partition_point.h
+++ b/libcxx/include/__algorithm/ranges_partition_point.h
@@ -35,9 +35,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __partition_point {
-
-struct __fn {
+struct __partition_point {
   // TODO(ranges): delegate to the classic algorithm.
   template <class _Iter, class _Sent, class _Proj, class _Pred>
   _LIBCPP_HIDE_FROM_ABI constexpr static _Iter
@@ -77,10 +75,8 @@ struct __fn {
   }
 };
 
-} // namespace __partition_point
-
 inline namespace __cpo {
-inline constexpr auto partition_point = __partition_point::__fn{};
+inline constexpr auto partition_point = __partition_point{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_pop_heap.h b/libcxx/include/__algorithm/ranges_pop_heap.h
index 01f92c0f2288..eccf54c094e3 100644
--- a/libcxx/include/__algorithm/ranges_pop_heap.h
+++ b/libcxx/include/__algorithm/ranges_pop_heap.h
@@ -40,9 +40,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __pop_heap {
-
-struct __fn {
+struct __pop_heap {
   template <class _Iter, class _Sent, class _Comp, class _Proj>
   _LIBCPP_HIDE_FROM_ABI constexpr static _Iter
   __pop_heap_fn_impl(_Iter __first, _Sent __last, _Comp& __comp, _Proj& __proj) {
@@ -70,10 +68,8 @@ struct __fn {
   }
 };
 
-} // namespace __pop_heap
-
 inline namespace __cpo {
-inline constexpr auto pop_heap = __pop_heap::__fn{};
+inline constexpr auto pop_heap = __pop_heap{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_prev_permutation.h b/libcxx/include/__algorithm/ranges_prev_permutation.h
index 225cee9b75ec..f2294b1cb00b 100644
--- a/libcxx/include/__algorithm/ranges_prev_permutation.h
+++ b/libcxx/include/__algorithm/ranges_prev_permutation.h
@@ -40,9 +40,7 @@ namespace ranges {
 template <class _InIter>
 using prev_permutation_result = in_found_result<_InIter>;
 
-namespace __prev_permutation {
-
-struct __fn {
+struct __prev_permutation {
   template <bidirectional_iterator _Iter, sentinel_for<_Iter> _Sent, class _Comp = ranges::less, class _Proj = identity>
     requires sortable<_Iter, _Comp, _Proj>
   _LIBCPP_HIDE_FROM_ABI constexpr prev_permutation_result<_Iter>
@@ -62,10 +60,8 @@ struct __fn {
   }
 };
 
-} // namespace __prev_permutation
-
 inline namespace __cpo {
-constexpr inline auto prev_permutation = __prev_permutation::__fn{};
+constexpr inline auto prev_permutation = __prev_permutation{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_push_heap.h b/libcxx/include/__algorithm/ranges_push_heap.h
index 9d187af38c53..c5e0465bdcfe 100644
--- a/libcxx/include/__algorithm/ranges_push_heap.h
+++ b/libcxx/include/__algorithm/ranges_push_heap.h
@@ -40,9 +40,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __push_heap {
-
-struct __fn {
+struct __push_heap {
   template <class _Iter, class _Sent, class _Comp, class _Proj>
   _LIBCPP_HIDE_FROM_ABI constexpr static _Iter
   __push_heap_fn_impl(_Iter __first, _Sent __last, _Comp& __comp, _Proj& __proj) {
@@ -69,10 +67,8 @@ struct __fn {
   }
 };
 
-} // namespace __push_heap
-
 inline namespace __cpo {
-inline constexpr auto push_heap = __push_heap::__fn{};
+inline constexpr auto push_heap = __push_heap{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_remove.h b/libcxx/include/__algorithm/ranges_remove.h
index 17c3a2c5cd06..6fbc49eba8a7 100644
--- a/libcxx/include/__algorithm/ranges_remove.h
+++ b/libcxx/include/__algorithm/ranges_remove.h
@@ -33,8 +33,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __remove {
-struct __fn {
+struct __remove {
   template <permutable _Iter, sentinel_for<_Iter> _Sent, class _Type, class _Proj = identity>
     requires indirect_binary_predicate<ranges::equal_to, projected<_Iter, _Proj>, const _Type*>
   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr subrange<_Iter>
@@ -52,10 +51,9 @@ struct __fn {
     return ranges::__remove_if_impl(ranges::begin(__range), ranges::end(__range), __pred, __proj);
   }
 };
-} // namespace __remove
 
 inline namespace __cpo {
-inline constexpr auto remove = __remove::__fn{};
+inline constexpr auto remove = __remove{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_remove_copy.h b/libcxx/include/__algorithm/ranges_remove_copy.h
index 84529eceac68..764c52ee16b2 100644
--- a/libcxx/include/__algorithm/ranges_remove_copy.h
+++ b/libcxx/include/__algorithm/ranges_remove_copy.h
@@ -38,9 +38,7 @@ namespace ranges {
 template <class _InIter, class _OutIter>
 using remove_copy_result = in_out_result<_InIter, _OutIter>;
 
-namespace __remove_copy {
-
-struct __fn {
+struct __remove_copy {
   template <input_iterator _InIter,
             sentinel_for<_InIter> _Sent,
             weakly_incrementable _OutIter,
@@ -65,10 +63,8 @@ struct __fn {
   }
 };
 
-} // namespace __remove_copy
-
 inline namespace __cpo {
-inline constexpr auto remove_copy = __remove_copy::__fn{};
+inline constexpr auto remove_copy = __remove_copy{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_remove_copy_if.h b/libcxx/include/__algorithm/ranges_remove_copy_if.h
index 56fe01753312..87136ae8258d 100644
--- a/libcxx/include/__algorithm/ranges_remove_copy_if.h
+++ b/libcxx/include/__algorithm/ranges_remove_copy_if.h
@@ -53,9 +53,7 @@ __remove_copy_if_impl(_InIter __first, _Sent __last, _OutIter __result, _Pred& _
   return {std::move(__first), std::move(__result)};
 }
 
-namespace __remove_copy_if {
-
-struct __fn {
+struct __remove_copy_if {
   template <input_iterator _InIter,
             sentinel_for<_InIter> _Sent,
             weakly_incrementable _OutIter,
@@ -79,10 +77,8 @@ struct __fn {
   }
 };
 
-} // namespace __remove_copy_if
-
 inline namespace __cpo {
-inline constexpr auto remove_copy_if = __remove_copy_if::__fn{};
+inline constexpr auto remove_copy_if = __remove_copy_if{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_remove_if.h b/libcxx/include/__algorithm/ranges_remove_if.h
index 0ea5d9a01b88..384b3d41d080 100644
--- a/libcxx/include/__algorithm/ranges_remove_if.h
+++ b/libcxx/include/__algorithm/ranges_remove_if.h
@@ -53,8 +53,7 @@ __remove_if_impl(_Iter __first, _Sent __last, _Pred& __pred, _Proj& __proj) {
   return {__new_end, __i};
 }
 
-namespace __remove_if {
-struct __fn {
+struct __remove_if {
   template <permutable _Iter,
             sentinel_for<_Iter> _Sent,
             class _Proj = identity,
@@ -73,10 +72,9 @@ struct __fn {
     return ranges::__remove_if_impl(ranges::begin(__range), ranges::end(__range), __pred, __proj);
   }
 };
-} // namespace __remove_if
 
 inline namespace __cpo {
-inline constexpr auto remove_if = __remove_if::__fn{};
+inline constexpr auto remove_if = __remove_if{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_replace.h b/libcxx/include/__algorithm/ranges_replace.h
index 2b88dc032972..15b1f38554a8 100644
--- a/libcxx/include/__algorithm/ranges_replace.h
+++ b/libcxx/include/__algorithm/ranges_replace.h
@@ -32,8 +32,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __replace {
-struct __fn {
+struct __replace {
   template <input_iterator _Iter, sentinel_for<_Iter> _Sent, class _Type1, class _Type2, class _Proj = identity>
     requires indirectly_writable<_Iter, const _Type2&> &&
              indirect_binary_predicate<ranges::equal_to, projected<_Iter, _Proj>, const _Type1*>
@@ -52,10 +51,9 @@ struct __fn {
     return ranges::__replace_if_impl(ranges::begin(__range), ranges::end(__range), __pred, __new_value, __proj);
   }
 };
-} // namespace __replace
 
 inline namespace __cpo {
-inline constexpr auto replace = __replace::__fn{};
+inline constexpr auto replace = __replace{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_replace_copy.h b/libcxx/include/__algorithm/ranges_replace_copy.h
index 633f993e5c94..7ab1c71543e2 100644
--- a/libcxx/include/__algorithm/ranges_replace_copy.h
+++ b/libcxx/include/__algorithm/ranges_replace_copy.h
@@ -38,9 +38,7 @@ namespace ranges {
 template <class _InIter, class _OutIter>
 using replace_copy_result = in_out_result<_InIter, _OutIter>;
 
-namespace __replace_copy {
-
-struct __fn {
+struct __replace_copy {
   template <input_iterator _InIter,
             sentinel_for<_InIter> _Sent,
             class _OldType,
@@ -77,10 +75,8 @@ struct __fn {
   }
 };
 
-} // namespace __replace_copy
-
 inline namespace __cpo {
-inline constexpr auto replace_copy = __replace_copy::__fn{};
+inline constexpr auto replace_copy = __replace_copy{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_replace_copy_if.h b/libcxx/include/__algorithm/ranges_replace_copy_if.h
index e065c3ac0acc..852ec45edaef 100644
--- a/libcxx/include/__algorithm/ranges_replace_copy_if.h
+++ b/libcxx/include/__algorithm/ranges_replace_copy_if.h
@@ -52,9 +52,7 @@ _LIBCPP_HIDE_FROM_ABI constexpr replace_copy_if_result<_InIter, _OutIter> __repl
   return {std::move(__first), std::move(__result)};
 }
 
-namespace __replace_copy_if {
-
-struct __fn {
+struct __replace_copy_if {
   template <input_iterator _InIter,
             sentinel_for<_InIter> _Sent,
             class _Type,
@@ -82,10 +80,8 @@ struct __fn {
   }
 };
 
-} // namespace __replace_copy_if
-
 inline namespace __cpo {
-inline constexpr auto replace_copy_if = __replace_copy_if::__fn{};
+inline constexpr auto replace_copy_if = __replace_copy_if{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_replace_if.h b/libcxx/include/__algorithm/ranges_replace_if.h
index 6445f42aea19..baa566810b5d 100644
--- a/libcxx/include/__algorithm/ranges_replace_if.h
+++ b/libcxx/include/__algorithm/ranges_replace_if.h
@@ -42,8 +42,7 @@ __replace_if_impl(_Iter __first, _Sent __last, _Pred& __pred, const _Type& __new
   return __first;
 }
 
-namespace __replace_if {
-struct __fn {
+struct __replace_if {
   template <input_iterator _Iter,
             sentinel_for<_Iter> _Sent,
             class _Type,
@@ -65,10 +64,9 @@ struct __fn {
     return ranges::__replace_if_impl(ranges::begin(__range), ranges::end(__range), __pred, __new_value, __proj);
   }
 };
-} // namespace __replace_if
 
 inline namespace __cpo {
-inline constexpr auto replace_if = __replace_if::__fn{};
+inline constexpr auto replace_if = __replace_if{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_reverse.h b/libcxx/include/__algorithm/ranges_reverse.h
index 9ec865995b4a..4e8211871977 100644
--- a/libcxx/include/__algorithm/ranges_reverse.h
+++ b/libcxx/include/__algorithm/ranges_reverse.h
@@ -27,8 +27,7 @@
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __reverse {
-struct __fn {
+struct __reverse {
   template <bidirectional_iterator _Iter, sentinel_for<_Iter> _Sent>
     requires permutable<_Iter>
   _LIBCPP_HIDE_FROM_ABI constexpr _Iter operator()(_Iter __first, _Sent __last) const {
@@ -65,10 +64,9 @@ struct __fn {
     return (*this)(ranges::begin(__range), ranges::end(__range));
   }
 };
-} // namespace __reverse
 
 inline namespace __cpo {
-inline constexpr auto reverse = __reverse::__fn{};
+inline constexpr auto reverse = __reverse{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_reverse_copy.h b/libcxx/include/__algorithm/ranges_reverse_copy.h
index 60043787a717..e5ca5cf652dc 100644
--- a/libcxx/include/__algorithm/ranges_reverse_copy.h
+++ b/libcxx/include/__algorithm/ranges_reverse_copy.h
@@ -37,8 +37,7 @@ namespace ranges {
 template <class _InIter, class _OutIter>
 using reverse_copy_result = in_out_result<_InIter, _OutIter>;
 
-namespace __reverse_copy {
-struct __fn {
+struct __reverse_copy {
   template <bidirectional_iterator _InIter, sentinel_for<_InIter> _Sent, weakly_incrementable _OutIter>
     requires indirectly_copyable<_InIter, _OutIter>
   _LIBCPP_HIDE_FROM_ABI constexpr reverse_copy_result<_InIter, _OutIter>
@@ -54,10 +53,9 @@ struct __fn {
     return {ranges::next(ranges::begin(__range), ranges::end(__range)), std::move(__ret.out)};
   }
 };
-} // namespace __reverse_copy
 
 inline namespace __cpo {
-inline constexpr auto reverse_copy = __reverse_copy::__fn{};
+inline constexpr auto reverse_copy = __reverse_copy{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_rotate.h b/libcxx/include/__algorithm/ranges_rotate.h
index 8d33a6f0799b..c1affc684ae4 100644
--- a/libcxx/include/__algorithm/ranges_rotate.h
+++ b/libcxx/include/__algorithm/ranges_rotate.h
@@ -33,9 +33,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __rotate {
-
-struct __fn {
+struct __rotate {
   template <class _Iter, class _Sent>
   _LIBCPP_HIDE_FROM_ABI constexpr static subrange<_Iter> __rotate_fn_impl(_Iter __first, _Iter __middle, _Sent __last) {
     auto __ret = std::__rotate<_RangeAlgPolicy>(std::move(__first), std::move(__middle), std::move(__last));
@@ -55,10 +53,8 @@ struct __fn {
   }
 };
 
-} // namespace __rotate
-
 inline namespace __cpo {
-inline constexpr auto rotate = __rotate::__fn{};
+inline constexpr auto rotate = __rotate{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_rotate_copy.h b/libcxx/include/__algorithm/ranges_rotate_copy.h
index 26fe110b5389..c0b4264a1b25 100644
--- a/libcxx/include/__algorithm/ranges_rotate_copy.h
+++ b/libcxx/include/__algorithm/ranges_rotate_copy.h
@@ -34,8 +34,7 @@ namespace ranges {
 template <class _InIter, class _OutIter>
 using rotate_copy_result = in_out_result<_InIter, _OutIter>;
 
-namespace __rotate_copy {
-struct __fn {
+struct __rotate_copy {
   template <forward_iterator _InIter, sentinel_for<_InIter> _Sent, weakly_incrementable _OutIter>
     requires indirectly_copyable<_InIter, _OutIter>
   _LIBCPP_HIDE_FROM_ABI constexpr rotate_copy_result<_InIter, _OutIter>
@@ -52,10 +51,9 @@ struct __fn {
     return (*this)(ranges::begin(__range), std::move(__middle), ranges::end(__range), std::move(__result));
   }
 };
-} // namespace __rotate_copy
 
 inline namespace __cpo {
-inline constexpr auto rotate_copy = __rotate_copy::__fn{};
+inline constexpr auto rotate_copy = __rotate_copy{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_sample.h b/libcxx/include/__algorithm/ranges_sample.h
index e4f60a7b66be..a3b29608150d 100644
--- a/libcxx/include/__algorithm/ranges_sample.h
+++ b/libcxx/include/__algorithm/ranges_sample.h
@@ -35,9 +35,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __sample {
-
-struct __fn {
+struct __sample {
   template <input_iterator _Iter, sentinel_for<_Iter> _Sent, weakly_incrementable _OutIter, class _Gen>
     requires(forward_iterator<_Iter> || random_access_iterator<_OutIter>) && indirectly_copyable<_Iter, _OutIter> &&
             uniform_random_bit_generator<remove_reference_t<_Gen>>
@@ -58,10 +56,8 @@ struct __fn {
   }
 };
 
-} // namespace __sample
-
 inline namespace __cpo {
-inline constexpr auto sample = __sample::__fn{};
+inline constexpr auto sample = __sample{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_search.h b/libcxx/include/__algorithm/ranges_search.h
index 55294c60631b..b71151203963 100644
--- a/libcxx/include/__algorithm/ranges_search.h
+++ b/libcxx/include/__algorithm/ranges_search.h
@@ -33,8 +33,7 @@
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __search {
-struct __fn {
+struct __search {
   template <class _Iter1, class _Sent1, class _Iter2, class _Sent2, class _Pred, class _Proj1, class _Proj2>
   _LIBCPP_HIDE_FROM_ABI static constexpr subrange<_Iter1> __ranges_search_impl(
       _Iter1 __first1,
@@ -120,10 +119,9 @@ struct __fn {
         __proj2);
   }
 };
-} // namespace __search
 
 inline namespace __cpo {
-inline constexpr auto search = __search::__fn{};
+inline constexpr auto search = __search{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_search_n.h b/libcxx/include/__algorithm/ranges_search_n.h
index 56e12755b9bf..81b568c0965f 100644
--- a/libcxx/include/__algorithm/ranges_search_n.h
+++ b/libcxx/include/__algorithm/ranges_search_n.h
@@ -39,8 +39,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __search_n {
-struct __fn {
+struct __search_n {
   template <class _Iter1, class _Sent1, class _SizeT, class _Type, class _Pred, class _Proj>
   _LIBCPP_HIDE_FROM_ABI static constexpr subrange<_Iter1> __ranges_search_n_impl(
       _Iter1 __first, _Sent1 __last, _SizeT __count, const _Type& __value, _Pred& __pred, _Proj& __proj) {
@@ -100,10 +99,9 @@ struct __fn {
     return __ranges_search_n_impl(ranges::begin(__range), ranges::end(__range), __count, __value, __pred, __proj);
   }
 };
-} // namespace __search_n
 
 inline namespace __cpo {
-inline constexpr auto search_n = __search_n::__fn{};
+inline constexpr auto search_n = __search_n{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_set_difference.h b/libcxx/include/__algorithm/ranges_set_difference.h
index 0841fb4ffd0c..aa36e358ef6f 100644
--- a/libcxx/include/__algorithm/ranges_set_difference.h
+++ b/libcxx/include/__algorithm/ranges_set_difference.h
@@ -42,9 +42,7 @@ namespace ranges {
 template <class _InIter, class _OutIter>
 using set_difference_result = in_out_result<_InIter, _OutIter>;
 
-namespace __set_difference {
-
-struct __fn {
+struct __set_difference {
   template <input_iterator _InIter1,
             sentinel_for<_InIter1> _Sent1,
             input_iterator _InIter2,
@@ -93,10 +91,8 @@ struct __fn {
   }
 };
 
-} // namespace __set_difference
-
 inline namespace __cpo {
-inline constexpr auto set_difference = __set_difference::__fn{};
+inline constexpr auto set_difference = __set_difference{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_set_intersection.h b/libcxx/include/__algorithm/ranges_set_intersection.h
index 9427379745b6..068794cf1b14 100644
--- a/libcxx/include/__algorithm/ranges_set_intersection.h
+++ b/libcxx/include/__algorithm/ranges_set_intersection.h
@@ -40,9 +40,7 @@ namespace ranges {
 template <class _InIter1, class _InIter2, class _OutIter>
 using set_intersection_result = in_in_out_result<_InIter1, _InIter2, _OutIter>;
 
-namespace __set_intersection {
-
-struct __fn {
+struct __set_intersection {
   template <input_iterator _InIter1,
             sentinel_for<_InIter1> _Sent1,
             input_iterator _InIter2,
@@ -98,10 +96,8 @@ struct __fn {
   }
 };
 
-} // namespace __set_intersection
-
 inline namespace __cpo {
-inline constexpr auto set_intersection = __set_intersection::__fn{};
+inline constexpr auto set_intersection = __set_intersection{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_set_symmetric_difference.h b/libcxx/include/__algorithm/ranges_set_symmetric_difference.h
index 995eb0999d94..e3b73c3eb1cf 100644
--- a/libcxx/include/__algorithm/ranges_set_symmetric_difference.h
+++ b/libcxx/include/__algorithm/ranges_set_symmetric_difference.h
@@ -40,9 +40,7 @@ namespace ranges {
 template <class _InIter1, class _InIter2, class _OutIter>
 using set_symmetric_difference_result = in_in_out_result<_InIter1, _InIter2, _OutIter>;
 
-namespace __set_symmetric_difference {
-
-struct __fn {
+struct __set_symmetric_difference {
   template <input_iterator _InIter1,
             sentinel_for<_InIter1> _Sent1,
             input_iterator _InIter2,
@@ -98,10 +96,8 @@ struct __fn {
   }
 };
 
-} // namespace __set_symmetric_difference
-
 inline namespace __cpo {
-inline constexpr auto set_symmetric_difference = __set_symmetric_difference::__fn{};
+inline constexpr auto set_symmetric_difference = __set_symmetric_difference{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_set_union.h b/libcxx/include/__algorithm/ranges_set_union.h
index e870e390cc66..f2e3ddb89d7b 100644
--- a/libcxx/include/__algorithm/ranges_set_union.h
+++ b/libcxx/include/__algorithm/ranges_set_union.h
@@ -43,9 +43,7 @@ namespace ranges {
 template <class _InIter1, class _InIter2, class _OutIter>
 using set_union_result = in_in_out_result<_InIter1, _InIter2, _OutIter>;
 
-namespace __set_union {
-
-struct __fn {
+struct __set_union {
   template <input_iterator _InIter1,
             sentinel_for<_InIter1> _Sent1,
             input_iterator _InIter2,
@@ -99,10 +97,8 @@ struct __fn {
   }
 };
 
-} // namespace __set_union
-
 inline namespace __cpo {
-inline constexpr auto set_union = __set_union::__fn{};
+inline constexpr auto set_union = __set_union{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_shuffle.h b/libcxx/include/__algorithm/ranges_shuffle.h
index ab98ea22caab..87cb3685bb95 100644
--- a/libcxx/include/__algorithm/ranges_shuffle.h
+++ b/libcxx/include/__algorithm/ranges_shuffle.h
@@ -39,9 +39,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __shuffle {
-
-struct __fn {
+struct __shuffle {
   template <random_access_iterator _Iter, sentinel_for<_Iter> _Sent, class _Gen>
     requires permutable<_Iter> && uniform_random_bit_generator<remove_reference_t<_Gen>>
   _LIBCPP_HIDE_FROM_ABI _Iter operator()(_Iter __first, _Sent __last, _Gen&& __gen) const {
@@ -56,10 +54,8 @@ struct __fn {
   }
 };
 
-} // namespace __shuffle
-
 inline namespace __cpo {
-inline constexpr auto shuffle = __shuffle::__fn{};
+inline constexpr auto shuffle = __shuffle{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_sort.h b/libcxx/include/__algorithm/ranges_sort.h
index 0296c146b3ed..2afad4c41301 100644
--- a/libcxx/include/__algorithm/ranges_sort.h
+++ b/libcxx/include/__algorithm/ranges_sort.h
@@ -39,9 +39,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __sort {
-
-struct __fn {
+struct __sort {
   template <class _Iter, class _Sent, class _Comp, class _Proj>
   _LIBCPP_HIDE_FROM_ABI constexpr static _Iter
   __sort_fn_impl(_Iter __first, _Sent __last, _Comp& __comp, _Proj& __proj) {
@@ -68,10 +66,8 @@ struct __fn {
   }
 };
 
-} // namespace __sort
-
 inline namespace __cpo {
-inline constexpr auto sort = __sort::__fn{};
+inline constexpr auto sort = __sort{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_sort_heap.h b/libcxx/include/__algorithm/ranges_sort_heap.h
index bab30df1708c..d3e20874fac5 100644
--- a/libcxx/include/__algorithm/ranges_sort_heap.h
+++ b/libcxx/include/__algorithm/ranges_sort_heap.h
@@ -40,9 +40,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __sort_heap {
-
-struct __fn {
+struct __sort_heap {
   template <class _Iter, class _Sent, class _Comp, class _Proj>
   _LIBCPP_HIDE_FROM_ABI constexpr static _Iter
   __sort_heap_fn_impl(_Iter __first, _Sent __last, _Comp& __comp, _Proj& __proj) {
@@ -69,10 +67,8 @@ struct __fn {
   }
 };
 
-} // namespace __sort_heap
-
 inline namespace __cpo {
-inline constexpr auto sort_heap = __sort_heap::__fn{};
+inline constexpr auto sort_heap = __sort_heap{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_stable_partition.h b/libcxx/include/__algorithm/ranges_stable_partition.h
index f34027ff772c..cfc02e1e97b3 100644
--- a/libcxx/include/__algorithm/ranges_stable_partition.h
+++ b/libcxx/include/__algorithm/ranges_stable_partition.h
@@ -42,9 +42,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __stable_partition {
-
-struct __fn {
+struct __stable_partition {
   template <class _Iter, class _Sent, class _Proj, class _Pred>
   _LIBCPP_HIDE_FROM_ABI static subrange<__remove_cvref_t<_Iter>>
   __stable_partition_fn_impl(_Iter&& __first, _Sent&& __last, _Pred&& __pred, _Proj&& __proj) {
@@ -76,10 +74,8 @@ struct __fn {
   }
 };
 
-} // namespace __stable_partition
-
 inline namespace __cpo {
-inline constexpr auto stable_partition = __stable_partition::__fn{};
+inline constexpr auto stable_partition = __stable_partition{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_stable_sort.h b/libcxx/include/__algorithm/ranges_stable_sort.h
index 93909e253cc0..9c7df80ae987 100644
--- a/libcxx/include/__algorithm/ranges_stable_sort.h
+++ b/libcxx/include/__algorithm/ranges_stable_sort.h
@@ -39,9 +39,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __stable_sort {
-
-struct __fn {
+struct __stable_sort {
   template <class _Iter, class _Sent, class _Comp, class _Proj>
   _LIBCPP_HIDE_FROM_ABI static _Iter __stable_sort_fn_impl(_Iter __first, _Sent __last, _Comp& __comp, _Proj& __proj) {
     auto __last_iter = ranges::next(__first, __last);
@@ -66,10 +64,8 @@ struct __fn {
   }
 };
 
-} // namespace __stable_sort
-
 inline namespace __cpo {
-inline constexpr auto stable_sort = __stable_sort::__fn{};
+inline constexpr auto stable_sort = __stable_sort{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_starts_with.h b/libcxx/include/__algorithm/ranges_starts_with.h
index 17084e4f2433..ae145d59010a 100644
--- a/libcxx/include/__algorithm/ranges_starts_with.h
+++ b/libcxx/include/__algorithm/ranges_starts_with.h
@@ -32,8 +32,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __starts_with {
-struct __fn {
+struct __starts_with {
   template <input_iterator _Iter1,
             sentinel_for<_Iter1> _Sent1,
             input_iterator _Iter2,
@@ -50,7 +49,7 @@ struct __fn {
       _Pred __pred   = {},
       _Proj1 __proj1 = {},
       _Proj2 __proj2 = {}) {
-    return __mismatch::__fn::__go(
+    return __mismatch::__go(
                std::move(__first1),
                std::move(__last1),
                std::move(__first2),
@@ -69,7 +68,7 @@ struct __fn {
     requires indirectly_comparable<iterator_t<_Range1>, iterator_t<_Range2>, _Pred, _Proj1, _Proj2>
   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI static constexpr bool
   operator()(_Range1&& __range1, _Range2&& __range2, _Pred __pred = {}, _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) {
-    return __mismatch::__fn::__go(
+    return __mismatch::__go(
                ranges::begin(__range1),
                ranges::end(__range1),
                ranges::begin(__range2),
@@ -80,9 +79,8 @@ struct __fn {
                .in2 == ranges::end(__range2);
   }
 };
-} // namespace __starts_with
 inline namespace __cpo {
-inline constexpr auto starts_with = __starts_with::__fn{};
+inline constexpr auto starts_with = __starts_with{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_swap_ranges.h b/libcxx/include/__algorithm/ranges_swap_ranges.h
index b6d9f618395a..ab6db50d8a13 100644
--- a/libcxx/include/__algorithm/ranges_swap_ranges.h
+++ b/libcxx/include/__algorithm/ranges_swap_ranges.h
@@ -36,8 +36,7 @@ namespace ranges {
 template <class _I1, class _I2>
 using swap_ranges_result = in_in_result<_I1, _I2>;
 
-namespace __swap_ranges {
-struct __fn {
+struct __swap_ranges {
   template <input_iterator _I1, sentinel_for<_I1> _S1, input_iterator _I2, sentinel_for<_I2> _S2>
     requires indirectly_swappable<_I1, _I2>
   _LIBCPP_HIDE_FROM_ABI constexpr swap_ranges_result<_I1, _I2>
@@ -54,10 +53,9 @@ struct __fn {
     return operator()(ranges::begin(__r1), ranges::end(__r1), ranges::begin(__r2), ranges::end(__r2));
   }
 };
-} // namespace __swap_ranges
 
 inline namespace __cpo {
-inline constexpr auto swap_ranges = __swap_ranges::__fn{};
+inline constexpr auto swap_ranges = __swap_ranges{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_transform.h b/libcxx/include/__algorithm/ranges_transform.h
index 7850ec4f8465..091311821968 100644
--- a/libcxx/include/__algorithm/ranges_transform.h
+++ b/libcxx/include/__algorithm/ranges_transform.h
@@ -41,8 +41,7 @@ using unary_transform_result = in_out_result<_Ip, _Op>;
 template <class _I1, class _I2, class _O1>
 using binary_transform_result = in_in_out_result<_I1, _I2, _O1>;
 
-namespace __transform {
-struct __fn {
+struct __transform {
 private:
   template <class _InIter, class _Sent, class _OutIter, class _Func, class _Proj>
   _LIBCPP_HIDE_FROM_ABI static constexpr unary_transform_result<_InIter, _OutIter>
@@ -161,10 +160,9 @@ public:
         __projection2);
   }
 };
-} // namespace __transform
 
 inline namespace __cpo {
-inline constexpr auto transform = __transform::__fn{};
+inline constexpr auto transform = __transform{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_unique.h b/libcxx/include/__algorithm/ranges_unique.h
index 7a9b78432187..a817359abd88 100644
--- a/libcxx/include/__algorithm/ranges_unique.h
+++ b/libcxx/include/__algorithm/ranges_unique.h
@@ -40,9 +40,7 @@ _LIBCPP_PUSH_MACROS
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __unique {
-
-struct __fn {
+struct __unique {
   template <permutable _Iter,
             sentinel_for<_Iter> _Sent,
             class _Proj                                                  = identity,
@@ -66,10 +64,8 @@ struct __fn {
   }
 };
 
-} // namespace __unique
-
 inline namespace __cpo {
-inline constexpr auto unique = __unique::__fn{};
+inline constexpr auto unique = __unique{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_unique_copy.h b/libcxx/include/__algorithm/ranges_unique_copy.h
index 61133885ae80..3b4a64e94ca1 100644
--- a/libcxx/include/__algorithm/ranges_unique_copy.h
+++ b/libcxx/include/__algorithm/ranges_unique_copy.h
@@ -44,12 +44,10 @@ namespace ranges {
 template <class _InIter, class _OutIter>
 using unique_copy_result = in_out_result<_InIter, _OutIter>;
 
-namespace __unique_copy {
-
 template <class _InIter, class _OutIter>
 concept __can_reread_from_output = (input_iterator<_OutIter> && same_as<iter_value_t<_InIter>, iter_value_t<_OutIter>>);
 
-struct __fn {
+struct __unique_copy {
   template <class _InIter, class _OutIter>
   static consteval auto __get_algo_tag() {
     if constexpr (forward_iterator<_InIter>) {
@@ -104,10 +102,8 @@ struct __fn {
   }
 };
 
-} // namespace __unique_copy
-
 inline namespace __cpo {
-inline constexpr auto unique_copy = __unique_copy::__fn{};
+inline constexpr auto unique_copy = __unique_copy{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__algorithm/ranges_upper_bound.h b/libcxx/include/__algorithm/ranges_upper_bound.h
index fa6fa7f70ed5..4b2835d4d58d 100644
--- a/libcxx/include/__algorithm/ranges_upper_bound.h
+++ b/libcxx/include/__algorithm/ranges_upper_bound.h
@@ -30,8 +30,7 @@
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
-namespace __upper_bound {
-struct __fn {
+struct __upper_bound {
   template <forward_iterator _Iter,
             sentinel_for<_Iter> _Sent,
             class _Type,
@@ -60,10 +59,9 @@ struct __fn {
         ranges::begin(__r), ranges::end(__r), __value, __comp_lhs_rhs_swapped, __proj);
   }
 };
-} // namespace __upper_bound
 
 inline namespace __cpo {
-inline constexpr auto upper_bound = __upper_bound::__fn{};
+inline constexpr auto upper_bound = __upper_bound{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__iterator/advance.h b/libcxx/include/__iterator/advance.h
index 296db1aaab65..57b1b845f1af 100644
--- a/libcxx/include/__iterator/advance.h
+++ b/libcxx/include/__iterator/advance.h
@@ -76,9 +76,7 @@ _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 void advance(_InputIter& __i
 // [range.iter.op.advance]
 
 namespace ranges {
-namespace __advance {
-
-struct __fn {
+struct __advance {
 private:
   template <class _Ip>
   _LIBCPP_HIDE_FROM_ABI static constexpr void __advance_forward(_Ip& __i, iter_difference_t<_Ip> __n) {
@@ -189,10 +187,8 @@ public:
   }
 };
 
-} // namespace __advance
-
 inline namespace __cpo {
-inline constexpr auto advance = __advance::__fn{};
+inline constexpr auto advance = __advance{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__iterator/distance.h b/libcxx/include/__iterator/distance.h
index 75bd49c9ae73..1732aa527f64 100644
--- a/libcxx/include/__iterator/distance.h
+++ b/libcxx/include/__iterator/distance.h
@@ -52,9 +52,7 @@ distance(_InputIter __first, _InputIter __last) {
 // [range.iter.op.distance]
 
 namespace ranges {
-namespace __distance {
-
-struct __fn {
+struct __distance {
   template <class _Ip, sentinel_for<_Ip> _Sp>
     requires(!sized_sentinel_for<_Sp, _Ip>)
   _LIBCPP_HIDE_FROM_ABI constexpr iter_difference_t<_Ip> operator()(_Ip __first, _Sp __last) const {
@@ -85,10 +83,8 @@ struct __fn {
   }
 };
 
-} // namespace __distance
-
 inline namespace __cpo {
-inline constexpr auto distance = __distance::__fn{};
+inline constexpr auto distance = __distance{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__iterator/next.h b/libcxx/include/__iterator/next.h
index 21d3688ad9eb..fb6c8ea6d755 100644
--- a/libcxx/include/__iterator/next.h
+++ b/libcxx/include/__iterator/next.h
@@ -41,9 +41,7 @@ next(_InputIter __x, typename iterator_traits<_InputIter>::difference_type __n =
 // [range.iter.op.next]
 
 namespace ranges {
-namespace __next {
-
-struct __fn {
+struct __next {
   template <input_or_output_iterator _Ip>
   _LIBCPP_HIDE_FROM_ABI constexpr _Ip operator()(_Ip __x) const {
     ++__x;
@@ -69,10 +67,8 @@ struct __fn {
   }
 };
 
-} // namespace __next
-
 inline namespace __cpo {
-inline constexpr auto next = __next::__fn{};
+inline constexpr auto next = __next{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__iterator/prev.h b/libcxx/include/__iterator/prev.h
index 2f0e6a088edb..e950d8dc4147 100644
--- a/libcxx/include/__iterator/prev.h
+++ b/libcxx/include/__iterator/prev.h
@@ -40,9 +40,7 @@ prev(_InputIter __x, typename iterator_traits<_InputIter>::difference_type __n =
 // [range.iter.op.prev]
 
 namespace ranges {
-namespace __prev {
-
-struct __fn {
+struct __prev {
   template <bidirectional_iterator _Ip>
   _LIBCPP_HIDE_FROM_ABI constexpr _Ip operator()(_Ip __x) const {
     --__x;
@@ -62,10 +60,8 @@ struct __fn {
   }
 };
 
-} // namespace __prev
-
 inline namespace __cpo {
-inline constexpr auto prev = __prev::__fn{};
+inline constexpr auto prev = __prev{};
 } // namespace __cpo
 } // namespace ranges
 
diff --git a/libcxx/include/__memory/ranges_construct_at.h b/libcxx/include/__memory/ranges_construct_at.h
index f731e75e7bdc..b7523d4ba4b8 100644
--- a/libcxx/include/__memory/ranges_construct_at.h
+++ b/libcxx/include/__memory/ranges_construct_at.h
@@ -38,43 +38,33 @@ namespace ranges {
 
 // construct_at
 
-namespace __construct_at {
-
-struct __fn {
+struct __construct_at {
   template <class _Tp, class... _Args, class = decltype(::new(std::declval<void*>()) _Tp(std::declval<_Args>()...))>
   _LIBCPP_HIDE_FROM_ABI constexpr _Tp* operator()(_Tp* __location, _Args&&... __args) const {
     return std::construct_at(__location, std::forward<_Args>(__args)...);
   }
 };
 
-} // namespace __construct_at
-
 inline namespace __cpo {
-inline constexpr auto construct_at = __construct_at::__fn{};
+inline constexpr auto construct_at = __construct_at{};
 } // namespace __cpo
 
 // destroy_at
 
-namespace __destroy_at {
-
-struct __fn {
+struct __destroy_at {
   template <destructible _Tp>
   _LIBCPP_HIDE_FROM_ABI constexpr void operator()(_Tp* __location) const noexcept {
     std::destroy_at(__location);
   }
 };
 
-} // namespace __destroy_at
-
 inline namespace __cpo {
-inline constexpr auto destroy_at = __destroy_at::__fn{};
+inline constexpr auto destroy_at = __destroy_at{};
 } // namespace __cpo
 
 // destroy
 
-namespace __destroy {
-
-struct __fn {
+struct __destroy {
   template <__nothrow_input_iterator _InputIterator, __nothrow_sentinel_for<_InputIterator> _Sentinel>
     requires destructible<iter_value_t<_InputIterator>>
   _LIBCPP_HIDE_FROM_ABI constexpr _InputIterator operator()(_InputIterator __first, _Sentinel __last) const noexcept {
@@ -88,17 +78,13 @@ struct __fn {
   }
 };
 
-} // namespace __destroy
-
 inline namespace __cpo {
-inline constexpr auto destroy = __destroy::__fn{};
+inline constexpr auto destroy = __destroy{};
 } // namespace __cpo
 
 // destroy_n
 
-namespace __destroy_n {
-
-struct __fn {
+struct __destroy_n {
   template <__nothrow_input_iterator _InputIterator>
     requires destructible<iter_value_t<_InputIterator>>
   _LIBCPP_HIDE_FROM_ABI constexpr _InputIterator
@@ -107,10 +93,8 @@ struct __fn {
   }
 };
 
-} // namespace __destroy_n
-
 inline namespace __cpo {
-inline constexpr auto destroy_n = __destroy_n::__fn{};
+inline constexpr auto destroy_n = __destroy_n{};
 } // namespace __cpo
 
 } // namespace ranges
diff --git a/libcxx/include/__memory/ranges_uninitialized_algorithms.h b/libcxx/include/__memory/ranges_uninitialized_algorithms.h
index 90090055bbbb..4815ac6e5de9 100644
--- a/libcxx/include/__memory/ranges_uninitialized_algorithms.h
+++ b/libcxx/include/__memory/ranges_uninitialized_algorithms.h
@@ -42,9 +42,7 @@ namespace ranges {
 
 // uninitialized_default_construct
 
-namespace __uninitialized_default_construct {
-
-struct __fn {
+struct __uninitialized_default_construct {
   template <__nothrow_forward_iterator _ForwardIterator, __nothrow_sentinel_for<_ForwardIterator> _Sentinel>
     requires default_initializable<iter_value_t<_ForwardIterator>>
   _LIBCPP_HIDE_FROM_ABI _ForwardIterator operator()(_ForwardIterator __first, _Sentinel __last) const {
@@ -59,17 +57,13 @@ struct __fn {
   }
 };
 
-} // namespace __uninitialized_default_construct
-
 inline namespace __cpo {
-inline constexpr auto uninitialized_default_construct = __uninitialized_default_construct::__fn{};
+inline constexpr auto uninitialized_default_construct = __uninitialized_default_construct{};
 } // namespace __cpo
 
 // uninitialized_default_construct_n
 
-namespace __uninitialized_default_construct_n {
-
-struct __fn {
+struct __uninitialized_default_construct_n {
   template <__nothrow_forward_iterator _ForwardIterator>
     requires default_initializable<iter_value_t<_ForwardIterator>>
   _LIBCPP_HIDE_FROM_ABI _ForwardIterator
@@ -79,17 +73,13 @@ struct __fn {
   }
 };
 
-} // namespace __uninitialized_default_construct_n
-
 inline namespace __cpo {
-inline constexpr auto uninitialized_default_construct_n = __uninitialized_default_construct_n::__fn{};
+inline constexpr auto uninitialized_default_construct_n = __uninitialized_default_construct_n{};
 } // namespace __cpo
 
 // uninitialized_value_construct
 
-namespace __uninitialized_value_construct {
-
-struct __fn {
+struct __uninitialized_value_construct {
   template <__nothrow_forward_iterator _ForwardIterator, __nothrow_sentinel_for<_ForwardIterator> _Sentinel>
     requires default_initializable<iter_value_t<_ForwardIterator>>
   _LIBCPP_HIDE_FROM_ABI _ForwardIterator operator()(_ForwardIterator __first, _Sentinel __last) const {
@@ -104,17 +94,13 @@ struct __fn {
   }
 };
 
-} // namespace __uninitialized_value_construct
-
 inline namespace __cpo {
-inline constexpr auto uninitialized_value_construct = __uninitialized_value_construct::__fn{};
+inline constexpr auto uninitialized_value_construct = __uninitialized_value_construct{};
 } // namespace __cpo
 
 // uninitialized_value_construct_n
 
-namespace __uninitialized_value_construct_n {
-
-struct __fn {
+struct __uninitialized_value_construct_n {
   template <__nothrow_forward_iterator _ForwardIterator>
     requires default_initializable<iter_value_t<_ForwardIterator>>
   _LIBCPP_HIDE_FROM_ABI _ForwardIterator
@@ -124,17 +110,13 @@ struct __fn {
   }
 };
 
-} // namespace __uninitialized_value_construct_n
-
 inline namespace __cpo {
-inline constexpr auto uninitialized_value_construct_n = __uninitialized_value_construct_n::__fn{};
+inline constexpr auto uninitialized_value_construct_n = __uninitialized_value_construct_n{};
 } // namespace __cpo
 
 // uninitialized_fill
 
-namespace __uninitialized_fill {
-
-struct __fn {
+struct __uninitialized_fill {
   template <__nothrow_forward_iterator _ForwardIterator, __nothrow_sentinel_for<_ForwardIterator> _Sentinel, class _Tp>
     requires constructible_from<iter_value_t<_ForwardIterator>, const _Tp&>
   _LIBCPP_HIDE_FROM_ABI _ForwardIterator operator()(_ForwardIterator __first, _Sentinel __last, const _Tp& __x) const {
@@ -149,17 +131,13 @@ struct __fn {
   }
 };
 
-} // namespace __uninitialized_fill
-
 inline namespace __cpo {
-inline constexpr auto uninitialized_fill = __uninitialized_fill::__fn{};
+inline constexpr auto uninitialized_fill = __uninitialized_fill{};
 } // namespace __cpo
 
 // uninitialized_fill_n
 
-namespace __uninitialized_fill_n {
-
-struct __fn {
+struct __uninitialized_fill_n {
   template <__nothrow_forward_iterator _ForwardIterator, class _Tp>
     requires constructible_from<iter_value_t<_ForwardIterator>, const _Tp&>
   _LIBCPP_HIDE_FROM_ABI _ForwardIterator
@@ -169,10 +147,8 @@ struct __fn {
   }
 };
 
-} // namespace __uninitialized_fill_n
-
 inline namespace __cpo {
-inline constexpr auto uninitialized_fill_n = __uninitialized_fill_n::__fn{};
+inline constexpr auto uninitialized_fill_n = __uninitialized_fill_n{};
 } // namespace __cpo
 
 // uninitialized_copy
@@ -180,9 +156,7 @@ inline constexpr auto uninitialized_fill_n = __uninitialized_fill_n::__fn{};
 template <class _InputIterator, class _OutputIterator>
 using uninitialized_copy_result = in_out_result<_InputIterator, _OutputIterator>;
 
-namespace __uninitialized_copy {
-
-struct __fn {
+struct __uninitialized_copy {
   template <input_iterator _InputIterator,
             sentinel_for<_InputIterator> _Sentinel1,
             __nothrow_forward_iterator _OutputIterator,
@@ -207,10 +181,8 @@ struct __fn {
   }
 };
 
-} // namespace __uninitialized_copy
-
 inline namespace __cpo {
-inline constexpr auto uninitialized_copy = __uninitialized_copy::__fn{};
+inline constexpr auto uninitialized_copy = __uninitialized_copy{};
 } // namespace __cpo
 
 // uninitialized_copy_n
@@ -218,9 +190,7 @@ inline constexpr auto uninitialized_copy = __uninitialized_copy::__fn{};
 template <class _InputIterator, class _OutputIterator>
 using uninitialized_copy_n_result = in_out_result<_InputIterator, _OutputIterator>;
 
-namespace __uninitialized_copy_n {
-
-struct __fn {
+struct __uninitialized_copy_n {
   template <input_iterator _InputIterator,
             __nothrow_forward_iterator _OutputIterator,
             __nothrow_sentinel_for<_OutputIterator> _Sentinel>
@@ -238,10 +208,8 @@ struct __fn {
   }
 };
 
-} // namespace __uninitialized_copy_n
-
 inline namespace __cpo {
-inline constexpr auto uninitialized_copy_n = __uninitialized_copy_n::__fn{};
+inline constexpr auto uninitialized_copy_n = __uninitialized_copy_n{};
 } // namespace __cpo
 
 // uninitialized_move
@@ -249,9 +217,7 @@ inline constexpr auto uninitialized_copy_n = __uninitialized_copy_n::__fn{};
 template <class _InputIterator, class _OutputIterator>
 using uninitialized_move_result = in_out_result<_InputIterator, _OutputIterator>;
 
-namespace __uninitialized_move {
-
-struct __fn {
+struct __uninitialized_move {
   template <input_iterator _InputIterator,
             sentinel_for<_InputIterator> _Sentinel1,
             __nothrow_forward_iterator _OutputIterator,
@@ -276,10 +242,8 @@ struct __fn {
   }
 };
 
-} // namespace __uninitialized_move
-
 inline namespace __cpo {
-inline constexpr auto uninitialized_move = __uninitialized_move::__fn{};
+inline constexpr auto uninitialized_move = __uninitialized_move{};
 } // namespace __cpo
 
 // uninitialized_move_n
@@ -287,9 +251,7 @@ inline constexpr auto uninitialized_move = __uninitialized_move::__fn{};
 template <class _InputIterator, class _OutputIterator>
 using uninitialized_move_n_result = in_out_result<_InputIterator, _OutputIterator>;
 
-namespace __uninitialized_move_n {
-
-struct __fn {
+struct __uninitialized_move_n {
   template <input_iterator _InputIterator,
             __nothrow_forward_iterator _OutputIterator,
             __nothrow_sentinel_for<_OutputIterator> _Sentinel>
@@ -308,10 +270,8 @@ struct __fn {
   }
 };
 
-} // namespace __uninitialized_move_n
-
 inline namespace __cpo {
-inline constexpr auto uninitialized_move_n = __uninitialized_move_n::__fn{};
+inline constexpr auto uninitialized_move_n = __uninitialized_move_n{};
 } // namespace __cpo
 
 } // namespace ranges