chore: bump C++ standard to 23

Author: zhjwpku

CMakeLists.txt

@@ -28,7 +28,7 @@ project(Iceberg
         DESCRIPTION "Iceberg C++ Project"
         LANGUAGES CXX)
 
-set(CMAKE_CXX_STANDARD 20)
+set(CMAKE_CXX_STANDARD 23)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_CXX_EXTENSIONS OFF)
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)

LICENSE

@@ -202,34 +202,6 @@
 
 --------------------------------------------------------------------------------
 
-The file src/iceberg/expected.h contains code adapted from
-
-https://github.com/zeus-cpp/expected
-
-with the following license (MIT)
-
-Copyright (c) 2024 zeus-cpp
-
-Permission is hereby granted, free of charge, to any person obtaining a copy
-of this software and associated documentation files (the "Software"), to deal
-in the Software without restriction, including without limitation the rights
-to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-copies of the Software, and to permit persons to whom the Software is
-furnished to do so, subject to the following conditions:
-
-The above copyright notice and this permission notice shall be included in all
-copies or substantial portions of the Software.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-SOFTWARE.
-
---------------------------------------------------------------------------------
-
 3rdparty dependency nlohmann-json is statically linked in certain binary
 distributions. nlohmann-json has the following license:
 

NOTICE

@@ -4,10 +4,6 @@ Copyright 2024-2025 The Apache Software Foundation
 This product includes software developed at
 The Apache Software Foundation (http://www.apache.org/).
 
-This product includes code from zeus-cpp
- * Copyright (c) 2024 zeus-cpp
- * https://github.com/zeus-cpp/expected
-
 This product includes code from smhasher
  * MurmurHash3 was written by Austin Appleby, and is placed in the public
  * domain. The author hereby disclaims copyright to this source code.

src/iceberg/arrow/arrow_error_transform_internal.h

@@ -38,8 +38,8 @@ inline ErrorKind ToErrorKind(const ::arrow::Status& status) {
 #define ICEBERG_ARROW_ASSIGN_OR_RETURN_IMPL(result_name, lhs, rexpr, error_transform) \
   auto&& result_name = (rexpr);                                                       \
   if (!result_name.ok()) {                                                            \
-    return unexpected<Error>{{.kind = error_transform(result_name.status()),          \
-                              .message = result_name.status().ToString()}};           \
+    return std::unexpected<Error>{{.kind = error_transform(result_name.status()),     \
+                                   .message = result_name.status().ToString()}};      \
   }                                                                                   \
   lhs = std::move(result_name).ValueOrDie();
 
@@ -51,7 +51,7 @@ inline ErrorKind ToErrorKind(const ::arrow::Status& status) {
   do {                                                                    \
     auto&& _status = (expr);                                              \
     if (!_status.ok()) {                                                  \
-      return unexpected<Error>{                                           \
+      return std::unexpected<Error>{                                      \
           {.kind = ToErrorKind(_status), .message = _status.ToString()}}; \
     }                                                                     \
   } while (0)

src/iceberg/avro/avro_reader.cc

@@ -210,6 +210,8 @@ class AvroBatchReader::Impl {
   std::unique_ptr<ReadContext> context_;
 };
 
+AvroBatchReader::~AvroBatchReader() = default;
+
 Result<Reader::Data> AvroBatchReader::Next() { return impl_->Next(); }
 
 Status AvroBatchReader::Open(const ReaderOptions& options) {

src/iceberg/avro/avro_reader.h

@@ -29,7 +29,7 @@ class ICEBERG_BUNDLE_EXPORT AvroBatchReader : public Reader {
  public:
   AvroBatchReader() = default;
 
-  ~AvroBatchReader() override = default;
+  ~AvroBatchReader() override;
 
   Status Open(const ReaderOptions& options) final;
 

src/iceberg/catalog/in_memory_catalog.cc

@@ -22,7 +22,6 @@
 #include <algorithm>
 #include <iterator>  // IWYU pragma: keep
 #include <mutex>
-#include <optional>
 #include <unordered_map>
 
 #include "iceberg/exception.h"
@@ -174,7 +173,7 @@ Result<bool> InMemoryNamespace::NamespaceExists(const Namespace& namespace_ident
   if (ns.error().kind == ErrorKind::kNoSuchNamespace) {
     return false;
   }
-  return unexpected<Error>(ns.error());
+  return std::unexpected<Error>(ns.error());
 }
 
 Result<std::vector<Namespace>> InMemoryNamespace::ListNamespaces(