Update libc++ to 34313583 (20 Feb 2022).

Notable changes:
* replace _LIBCPP_INLINE_VISIBILITY with _LIBCPP_HIDE_FROM_ABI in __filesystem/operations.h
* implement sortable and mergeable concepts
* replace __uncvref with __uncvref_t
* implement consistent stateful allocator behavior in std::basic_string::operator+
* remove some _LIBCPP_CXX03_LANG ifdef's
* move _LIBCPP_ASSERT related code to a separate file
* enable std::hash<Enum> in C++11 mode
* make algorithm includes more granular
* implement range functionality for std::istream_iterator
* add debug check in basic_string::insert
* replace "" with <> in includes in src/ files for consistency with include/
* add push/pop macros defines in src/ files for consistency with include/
* add availability annotations to optional operations
* remove conditional noexcept from view_interface --- this is allowed by the standard
* replace _LIBCPP_SAFE_STATIC with _LIBCPP_CONSTINIT
* guard most of std::ranges under _LIBCPP_HAS_NO_INCOMPLETE_RANGES
* remove priority pragma for AIX from locale.cpp because it is ignored anyway

1 files changed, 38 insertions, 0 deletions

diff --git a/contrib/libs/cxxsupp/libcxx/src/assert.cpp b/contrib/libs/cxxsupp/libcxx/src/assert.cpp
new file mode 100644
index 00000000000..21a3863cd05
--- /dev/null
+++ b/contrib/libs/cxxsupp/libcxx/src/assert.cpp
@@ -0,0 +1,38 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__assert>
+#include <__config>
+#include <cstdio>
+#include <cstdlib>
+#include <string>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+std::string __libcpp_debug_info::what() const {
+  string msg = __file_;
+  msg += ":" + std::to_string(__line_) + ": _LIBCPP_ASSERT '";
+  msg += __pred_;
+  msg += "' failed. ";
+  msg += __msg_;
+  return msg;
+}
+
+_LIBCPP_NORETURN void __libcpp_abort_debug_function(__libcpp_debug_info const& info) {
+    std::fprintf(stderr, "%s\n", info.what().c_str());
+    std::abort();
+}
+
+_LIBCPP_CONSTINIT __libcpp_debug_function_type __libcpp_debug_function = __libcpp_abort_debug_function;
+
+bool __libcpp_set_debug_function(__libcpp_debug_function_type __func) {
+  __libcpp_debug_function = __func;
+  return true;
+}
+
+_LIBCPP_END_NAMESPACE_STD