Merge branch 'llvm18'

Upgrades the LLVM, Clang, and LLD dependencies to LLVM 18.x

Related to #16270

1 files changed, 113 insertions, 0 deletions

diff --git a/lib/libcxx/src/tzdb_list.cpp b/lib/libcxx/src/tzdb_list.cpp
new file mode 100644
index 0000000000..7eaaedc6ed
--- /dev/null
+++ b/lib/libcxx/src/tzdb_list.cpp
@@ -0,0 +1,113 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// For information see https://libcxx.llvm.org/DesignDocs/TimeZone.html
+
+#include <chrono>
+
+#include <__mutex/unique_lock.h>
+#include <forward_list>
+
+// When threads are not available the locking is not required.
+#ifndef _LIBCPP_HAS_NO_THREADS
+#  include <shared_mutex>
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace chrono {
+
+//===----------------------------------------------------------------------===//
+//                          Private API
+//===----------------------------------------------------------------------===//
+
+class tzdb_list::__impl {
+public:
+  explicit __impl(tzdb&& __tzdb) { __tzdb_.push_front(std::move(__tzdb)); }
+
+  using const_iterator = tzdb_list::const_iterator;
+
+  const tzdb& front() const noexcept {
+#ifndef _LIBCPP_HAS_NO_THREADS
+    shared_lock __lock{__mutex_};
+#endif
+    return __tzdb_.front();
+  }
+
+  const_iterator erase_after(const_iterator __p) {
+#ifndef _LIBCPP_HAS_NO_THREADS
+    unique_lock __lock{__mutex_};
+#endif
+    return __tzdb_.erase_after(__p);
+  }
+
+  tzdb& __emplace_front(tzdb&& __tzdb) {
+#ifndef _LIBCPP_HAS_NO_THREADS
+    unique_lock __lock{__mutex_};
+#endif
+    return __tzdb_.emplace_front(std::move(__tzdb));
+  }
+
+  const_iterator begin() const noexcept {
+#ifndef _LIBCPP_HAS_NO_THREADS
+    shared_lock __lock{__mutex_};
+#endif
+    return __tzdb_.begin();
+  }
+  const_iterator end() const noexcept {
+    //  forward_list<T>::end does not access the list, so no need to take a lock.
+    return __tzdb_.end();
+  }
+
+  const_iterator cbegin() const noexcept { return begin(); }
+  const_iterator cend() const noexcept { return end(); }
+
+private:
+#ifndef _LIBCPP_HAS_NO_THREADS
+  mutable shared_mutex __mutex_;
+#endif
+  forward_list<tzdb> __tzdb_;
+};
+
+//===----------------------------------------------------------------------===//
+//                           Public API
+//===----------------------------------------------------------------------===//
+
+_LIBCPP_EXPORTED_FROM_ABI tzdb_list::tzdb_list(tzdb&& __tzdb) : __impl_{new __impl(std::move(__tzdb))} {}
+
+_LIBCPP_EXPORTED_FROM_ABI tzdb_list::~tzdb_list() { delete __impl_; }
+
+_LIBCPP_NODISCARD_EXT _LIBCPP_EXPORTED_FROM_ABI const tzdb& tzdb_list::front() const noexcept {
+  return __impl_->front();
+}
+
+_LIBCPP_EXPORTED_FROM_ABI tzdb_list::const_iterator tzdb_list::erase_after(const_iterator __p) {
+  return __impl_->erase_after(__p);
+}
+
+_LIBCPP_EXPORTED_FROM_ABI tzdb& tzdb_list::__emplace_front(tzdb&& __tzdb) {
+  return __impl_->__emplace_front(std::move(__tzdb));
+}
+
+_LIBCPP_NODISCARD_EXT _LIBCPP_EXPORTED_FROM_ABI tzdb_list::const_iterator tzdb_list::begin() const noexcept {
+  return __impl_->begin();
+}
+_LIBCPP_NODISCARD_EXT _LIBCPP_EXPORTED_FROM_ABI tzdb_list::const_iterator tzdb_list::end() const noexcept {
+  return __impl_->end();
+}
+
+_LIBCPP_NODISCARD_EXT _LIBCPP_EXPORTED_FROM_ABI tzdb_list::const_iterator tzdb_list::cbegin() const noexcept {
+  return __impl_->cbegin();
+}
+_LIBCPP_NODISCARD_EXT _LIBCPP_EXPORTED_FROM_ABI tzdb_list::const_iterator tzdb_list::cend() const noexcept {
+  return __impl_->cend();
+}
+
+} // namespace chrono
+
+_LIBCPP_END_NAMESPACE_STD