Fix compile errors in C++23 (#12106)

Summary:
This PR fixes compile errors in C++23.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/12106

Reviewed By: cbi42

Differential Revision: D57826279

Pulled By: ajkr

fbshipit-source-id: 594abfd8eceaf51eaf3bbabf7696c0bb5e0e9a68

db/range_tombstone_fragmenter.h

@@ -17,16 +17,6 @@
 #include "table/internal_iterator.h"
 
 namespace ROCKSDB_NAMESPACE {
-struct FragmentedRangeTombstoneList;
-
-struct FragmentedRangeTombstoneListCache {
-  // ensure only the first reader needs to initialize l
-  std::mutex reader_mutex;
-  std::unique_ptr<FragmentedRangeTombstoneList> tombstones = nullptr;
-  // readers will first check this bool to avoid
-  std::atomic<bool> initialized = false;
-};
-
 struct FragmentedRangeTombstoneList {
  public:
   // A compact representation of a "stack" of range tombstone fragments, which
@@ -124,6 +114,14 @@ struct FragmentedRangeTombstoneList {
   uint64_t total_tombstone_payload_bytes_;
 };
 
+struct FragmentedRangeTombstoneListCache {
+  // ensure only the first reader needs to initialize l
+  std::mutex reader_mutex;
+  std::unique_ptr<FragmentedRangeTombstoneList> tombstones = nullptr;
+  // readers will first check this bool to avoid
+  std::atomic<bool> initialized = false;
+};
+
 // FragmentedRangeTombstoneIterator converts an InternalIterator of a range-del
 // meta block into an iterator over non-overlapping tombstone fragments. The
 // tombstone fragmentation process should be more efficient than the range

db/write_batch.cc

@@ -65,6 +65,7 @@
 #include "port/lang.h"
 #include "rocksdb/merge_operator.h"
 #include "rocksdb/system_clock.h"
+#include "util/aligned_storage.h"
 #include "util/autovector.h"
 #include "util/cast_util.h"
 #include "util/coding.h"
@@ -1900,7 +1901,7 @@ class MemTableInserter : public WriteBatch::Handler {
   // Make creation optional but do not incur
   // std::unique_ptr additional allocation
   using MemPostInfoMap = std::map<MemTable*, MemTablePostProcessInfo>;
-  using PostMapType = std::aligned_storage<sizeof(MemPostInfoMap)>::type;
+  using PostMapType = aligned_storage<MemPostInfoMap>::type;
   PostMapType mem_post_info_map_;
   // current recovered transaction we are rebuilding (recovery)
   WriteBatch* rebuilding_trx_;
@@ -1914,7 +1915,7 @@ class MemTableInserter : public WriteBatch::Handler {
   bool write_before_prepare_;
   // Whether this batch was unprepared or not
   bool unprepared_batch_;
-  using DupDetector = std::aligned_storage<sizeof(DuplicateDetector)>::type;
+  using DupDetector = aligned_storage<DuplicateDetector>::type;
   DupDetector duplicate_detector_;
   bool dup_dectector_on_;
 
@@ -1922,7 +1923,7 @@ class MemTableInserter : public WriteBatch::Handler {
   bool hint_created_;
   // Hints for this batch
   using HintMap = std::unordered_map<MemTable*, void*>;
-  using HintMapType = std::aligned_storage<sizeof(HintMap)>::type;
+  using HintMapType = aligned_storage<HintMap>::type;
   HintMapType hint_;
 
   HintMap& GetHintMap() {

db/write_thread.h

@@ -23,6 +23,7 @@
 #include "rocksdb/status.h"
 #include "rocksdb/types.h"
 #include "rocksdb/write_batch.h"
+#include "util/aligned_storage.h"
 #include "util/autovector.h"
 
 namespace ROCKSDB_NAMESPACE {
@@ -134,8 +135,8 @@ class WriteThread {
     Status status;
     Status callback_status;  // status returned by callback->Callback()
 
-    std::aligned_storage<sizeof(std::mutex)>::type state_mutex_bytes;
-    std::aligned_storage<sizeof(std::condition_variable)>::type state_cv_bytes;
+    aligned_storage<std::mutex>::type state_mutex_bytes;
+    aligned_storage<std::condition_variable>::type state_cv_bytes;
     Writer* link_older;  // read/write only before linking, or as leader
     Writer* link_newer;  // lazy, read/write only before linking, or as leader
 

util/aligned_storage.h

@@ -0,0 +1,24 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+#pragma once
+
+#include <cstddef>
+
+#include "rocksdb/rocksdb_namespace.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+template <typename T, std::size_t Align = alignof(T)>
+struct aligned_storage {
+  struct type {
+    alignas(Align) unsigned char data[sizeof(T)];
+  };
+};
+
+}  // namespace ROCKSDB_NAMESPACE

util/random.cc

@@ -13,6 +13,7 @@
 #include <utility>
 
 #include "port/likely.h"
+#include "util/aligned_storage.h"
 #include "util/thread_local.h"
 
 #define STORAGE_DECL static thread_local
@@ -21,7 +22,7 @@ namespace ROCKSDB_NAMESPACE {
 
 Random* Random::GetTLSInstance() {
   STORAGE_DECL Random* tls_instance;
-  STORAGE_DECL std::aligned_storage<sizeof(Random)>::type tls_instance_bytes;
+  STORAGE_DECL aligned_storage<Random>::type tls_instance_bytes;
 
   auto rv = tls_instance;
   if (UNLIKELY(rv == nullptr)) {

util/xxhash.h

@@ -11,6 +11,15 @@
 #ifndef XXH_NAMESPACE
 #define XXH_NAMESPACE ROCKSDB_
 #endif  // !defined(XXH_NAMESPACE)
+
+#if (defined(XXH_INLINE_ALL) || defined(XXH_PRIVATE_API) || \
+     defined(XXH_IMPLEMENTATION)) &&                        \
+    !defined(XXH_IMPLEM_13a8737387)
+#if defined(__cplusplus) && (__cplusplus > 202002L)
+/* C++23 and future versions have std::unreachable() */
+#include <utility> /* std::unreachable() */
+#endif
+#endif
 /* END RocksDB customizations */
 
 // clang-format off
@@ -2064,8 +2073,6 @@ static int XXH_isLittleEndian(void)
 #  define XXH_UNREACHABLE() unreachable()
 
 #elif defined(__cplusplus) && (__cplusplus > 202002L)
-/* C++23 and future versions have std::unreachable() */
-#  include <utility> /* std::unreachable() */
 #  define XXH_UNREACHABLE() std::unreachable()
 
 #elif XXH_HAS_BUILTIN(__builtin_unreachable)

utilities/write_batch_with_index/write_batch_with_index_internal.cc

@@ -36,6 +36,8 @@ BaseDeltaIterator::BaseDeltaIterator(ColumnFamilyHandle* column_family,
   assert(comparator_);
 }
 
+BaseDeltaIterator::~BaseDeltaIterator() = default;
+
 bool BaseDeltaIterator::Valid() const {
   return status_.ok() ? (current_at_base_ ? BaseValid() : DeltaValid()) : false;
 }

utilities/write_batch_with_index/write_batch_with_index_internal.h

@@ -38,7 +38,7 @@ class BaseDeltaIterator : public Iterator {
                     WBWIIteratorImpl* delta_iterator,
                     const Comparator* comparator);
 
-  ~BaseDeltaIterator() override {}
+  ~BaseDeltaIterator() override;
 
   bool Valid() const override;
   void SeekToFirst() override;