Update libc++ to b6d87773 (14 Jan 2022).

Notable changes:
* implement operator << for filesystem::directory_entry
* add std::ranges::in_in_result
* add std::ranges::owning_view
* add std::ranges::cdata
* add std::ranges::construct_at and destroy{,_n,_at}
* small fixes in std::ranges::data
* SFINAE away std::ranges::cbegin(const T&&) for non-borrowed T
* use arc4random to implement std::random_device on Apple
* introduce __fits_in_sso to put constexpr check into a central place
* introduce __debug_db_insert_c to put #if and constexpr check into a central place

ref:b3dd06bd52f06e8939227ca0f0a5873d0c211e48

1 files changed, 17 insertions, 6 deletions

diff --git a/contrib/libs/cxxsupp/libcxx/include/__ranges/concepts.h b/contrib/libs/cxxsupp/libcxx/include/__ranges/concepts.h
index bad23c8c4b..fa31074ab6 100644
--- a/contrib/libs/cxxsupp/libcxx/include/__ranges/concepts.h
+++ b/contrib/libs/cxxsupp/libcxx/include/__ranges/concepts.h
@@ -9,6 +9,9 @@
 #ifndef _LIBCPP___RANGES_CONCEPTS_H
 #define _LIBCPP___RANGES_CONCEPTS_H
 
+#include <__concepts/constructible.h>
+#include <__concepts/movable.h>
+#include <__concepts/same_as.h>
 #include <__config>
 #include <__iterator/concepts.h>
 #include <__iterator/incrementable_traits.h>
@@ -20,7 +23,7 @@
 #include <__ranges/enable_borrowed_range.h>
 #include <__ranges/enable_view.h>
 #include <__ranges/size.h>
-#include <concepts>
+#include <initializer_list>
 #include <type_traits>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
@@ -114,12 +117,20 @@ namespace ranges {
   template <class _Tp>
   concept common_range = range<_Tp> && same_as<iterator_t<_Tp>, sentinel_t<_Tp>>;
 
-  template<class _Tp>
+  template <class _Tp>
+  inline constexpr bool __is_std_initializer_list = false;
+
+  template <class _Ep>
+  inline constexpr bool __is_std_initializer_list<initializer_list<_Ep>> = true;
+
+  template <class _Tp>
   concept viewable_range =
-    range<_Tp> && (
-      (view<remove_cvref_t<_Tp>> && constructible_from<remove_cvref_t<_Tp>, _Tp>) ||
-      (!view<remove_cvref_t<_Tp>> && borrowed_range<_Tp>)
-    );
+    range<_Tp> &&
+    ((view<remove_cvref_t<_Tp>> && constructible_from<remove_cvref_t<_Tp>, _Tp>) ||
+     (!view<remove_cvref_t<_Tp>> &&
+      (is_lvalue_reference_v<_Tp> ||
+       (movable<remove_reference_t<_Tp>> && !__is_std_initializer_list<remove_cvref_t<_Tp>>))));
+
 } // namespace ranges
 
 #endif // !defined(_LIBCPP_HAS_NO_RANGES)