diff --git a/libcxx/include/__ranges/all.h b/libcxx/include/__ranges/all.h
--- a/libcxx/include/__ranges/all.h
+++ b/libcxx/include/__ranges/all.h
@@ -34,43 +34,39 @@
 
 namespace views {
 
-namespace __all {
-  struct __fn {
-    template<class _Tp>
-      requires ranges::view<decay_t<_Tp>>
-    _LIBCPP_HIDE_FROM_ABI
-    constexpr auto operator()(_Tp&& __t) const
-      noexcept(noexcept(_VSTD::__decay_copy(_VSTD::forward<_Tp>(__t))))
-    {
-      return _VSTD::forward<_Tp>(__t);
-    }
-
-    template<class _Tp>
-      requires (!ranges::view<decay_t<_Tp>>) &&
-               requires (_Tp&& __t) { ranges::ref_view{_VSTD::forward<_Tp>(__t)}; }
-    _LIBCPP_HIDE_FROM_ABI
-    constexpr auto operator()(_Tp&& __t) const
-      noexcept(noexcept(ranges::ref_view{_VSTD::forward<_Tp>(__t)}))
-    {
-      return ranges::ref_view{_VSTD::forward<_Tp>(__t)};
-    }
-
-    template<class _Tp>
-      requires (!ranges::view<decay_t<_Tp>> &&
-                !requires (_Tp&& __t) { ranges::ref_view{_VSTD::forward<_Tp>(__t)}; } &&
-                 requires (_Tp&& __t) { ranges::subrange{_VSTD::forward<_Tp>(__t)}; })
-    _LIBCPP_HIDE_FROM_ABI
-    constexpr auto operator()(_Tp&& __t) const
-      noexcept(noexcept(ranges::subrange{_VSTD::forward<_Tp>(__t)}))
-    {
-      return ranges::subrange{_VSTD::forward<_Tp>(__t)};
-    }
-  };
-}
-
-inline namespace __cpo {
-  inline constexpr auto all = __all::__fn{};
-} // namespace __cpo
+struct __all_adaptor {
+  template<class _Tp>
+    requires ranges::view<decay_t<_Tp>>
+  _LIBCPP_HIDE_FROM_ABI
+  constexpr auto operator()(_Tp&& __t) const
+    noexcept(noexcept(_VSTD::__decay_copy(_VSTD::forward<_Tp>(__t))))
+  {
+    return _VSTD::forward<_Tp>(__t);
+  }
+
+  template<class _Tp>
+    requires (!ranges::view<decay_t<_Tp>>) &&
+              requires (_Tp&& __t) { ranges::ref_view{_VSTD::forward<_Tp>(__t)}; }
+  _LIBCPP_HIDE_FROM_ABI
+  constexpr auto operator()(_Tp&& __t) const
+    noexcept(noexcept(ranges::ref_view{_VSTD::forward<_Tp>(__t)}))
+  {
+    return ranges::ref_view{_VSTD::forward<_Tp>(__t)};
+  }
+
+  template<class _Tp>
+    requires (!ranges::view<decay_t<_Tp>> &&
+              !requires (_Tp&& __t) { ranges::ref_view{_VSTD::forward<_Tp>(__t)}; } &&
+                requires (_Tp&& __t) { ranges::subrange{_VSTD::forward<_Tp>(__t)}; })
+  _LIBCPP_HIDE_FROM_ABI
+  constexpr auto operator()(_Tp&& __t) const
+    noexcept(noexcept(ranges::subrange{_VSTD::forward<_Tp>(__t)}))
+  {
+    return ranges::subrange{_VSTD::forward<_Tp>(__t)};
+  }
+};
+
+inline constexpr auto all = __all_adaptor{};
 
 template<ranges::viewable_range _Range>
 using all_t = decltype(views::all(declval<_Range>()));