Protocol Buffers 22.0

What's new in this version:

Announcements:
- This version includes breaking changes to: Cpp
- [Cpp] Migrate to Abseil's logging library
- [Cpp] proto2::Map::value_type changes to std::pair<const K, V>
- [Cpp] Mark final ZeroCopyInputStream, ZeroCopyOutputStream, and DefaultFieldComparator classes
- [Cpp] Add a dependency on Abseil
- [Cpp] Remove all autotools usage
- [Cpp] Add C++20 reserved keywords
- [Cpp] Delete Arena::Init
- [Cpp] Replace JSON parser with new implementation
- [Cpp] Make RepeatedField::GetArena non-const in order to support split RepeatedFields.
- You can refer to our migration guide for details on what C++ code changes will be necessary to be compatible with 22.0
- Protobuf News may include additional announcements or pre-announcements for upcoming changes

Compiler:
- Breaking change: Migrate to Abseil's logging library
- Add debug_redact field option to protobuf
- Protoc: accept capital X to indicate hex escape in string literals
- Gracefully handle weird placement of linebreaks around comments
- Open up visibility for some compiler internals
- Protoc: validate reserved names are identifiers
- Protoc: validate custom json_name configuration
- Protoc: fix consistency with parsing very large decimal numbers
- Use protoc version for --version
- Fix for grpc.tools #17995 & protobuf #7474 (handle UTF-8 paths in argumentfile)
- Print full path name of source .proto file on error
- Include proto message type in the annotation comments.
- Maven artifact suffix format has changed to -RCN instead of -rc-N

C++:
- Document known quirks of EnumDescriptor::is_closed() when importing across files with different syntaxes
- Add C++ support for retention attribute
- Breaking change: Migrate to Abseil's logging library
- No longer define no_threadlocal on OpenBSD
- CMake: Enable projects to set the C++ version
- Breaking Change: Add a dependency on Abseil
- Upgrade third_party/googletest submodule to current main branch
- Breaking Change: Remove all autotools usage
- CMake: use add_compile_options instead of add_definitions for compile options
- Fix #9947: make the ABI identical between debug and non-debug builds
- Allow for CMAKE_INSTALL_LIBDIR to be absolute
- Add header search paths to protobuf-c++ spec
- Cpp_generated_lib_linked support is removed in protoc
- Reduced .pb.o object file size slightly by explicitly instantiating
- Breaking Change: Add C++20 reserved keywords
- Fixed crash in ThreadLocalStorage for pre-C++17 compilers on 32-bit ARM
- Clarified that JSON API non-OK statuses are not a stable API
- Added a default implementation of MessageDifferencer::Reporter methods
- Proto2::MapPair is now an alias to std::pair
- Hide C++ RepeatedField::UnsafeArenaSwap
- Use table-driven parser for reflection based objects
- Add ARM-optimized Varint decoding functions
- Minor optimization for parsing groups
- Declare ReflectiveProtoHook class
- Reduce size of VarintParse code in protocol buffers, by calling the shared
- Avoid inlining some large heavily duplicated routines in repeated_ptr_field.h
- Add ReflectiveProtoHook to Reflection.
- Turns on table-driven parser for reflection based objects.
- Save code space by avoiding inlining of large-in-aggregate code-space MessageLite::~MessageLite destructor.
- Undefine the macro linux when compiling protobuf
- Reduce memory consumption of MessageSet parsing.
- Save code space by avoiding inlining of large-in-aggregate code-space MessageLite::~MessageLite destructor.
- Breaking Change: Delete Arena::Init
- Make a PROTOBUF_POISON/UNPOISON to reduce noise in the source
- Put alignment functions in "arena_align.h"
- Split off cleanup arena functions into "arena_cleanup.h"
- Fix signed / unsigned match in CHECK_EQ
- Kill Atomic<>. it's not pulling it's weight
- Move AllocationPolicy out of arena_impl, and unify arena_config for bazel
- Fix failure case in table-driven parser.
- Breaking Change: Replace JSON parser with new implementation
- Introduce the Printer::{SetRedactDebugString,SetRandomizeDebugString} private flags
- Introduce global flags to control Printer::{SetRedactDebugString, SetRandomizeDebugString}
- Proto3 string fields no longer trigger clang-tidy warning bugprone-branch-clone
- Fix the API of DescriptorUpgrader::set_allow_unknown_dependencies to set to True always, and to populate into the DescriptorPool as well
- Report line numbers consistently in text-format deprecated-field warnings
- Fixed C++ code generation for protos that use int32_t, uint32_t, int64_t, uint64_t, size_t as field names
- Annotate generated C++ public aliases for enum types
- Change default arena max block size from 8K to 32K
- Begin emitting semantic metadata for some C++ proto features

Java:
- Document known quirks of EnumDescriptor::is_closed() when importing across files with different syntaxes
- Use LazyStringArrayList directly in gencode
- Add Java support for retention attribute
- Expect fail when serialize inf and nan for Value.number_value in json format
- Create a helper function that can make a mutable copy of any ProtobufList
- Add debug_redact field option to protobuf
- Remove unused package private class ProtobufLists
- Mark UnmodifiableLazyStringList deprecated. UnmodifiableLazyStringList is unnecessary and will be removed in a future release
- Make emptyList public and mark the public EMPTY field as deprecated
- Enable Text format parser to skip unknown short-formed repeated fields
- Expose internal setExtension method for Kotlin
- Mark default instance as immutable first to avoid race during static initialization of default instances
- Add serialVersionUID to ByteString and subclasses
- Fix serialization warnings in generated code when compiling with Java 18 and above
- Fix Timestamps fromDate for negative 'exact second' java.sql.Timestamps
- Fix Timestamps.fromDate to correctly handle java.sql.Timestamps before unix epoch
- Performance improvement for repeated use of FieldMaskUtil#merge by caching
- Optimized Java proto serialization gencode for protos having many extension ranges with few fields in between
- More thoroughly annotate public generated code in Java lite protocol buffers
- Fixed Bug in proto3 java lite repeated enum fields. Failed to call copyOnWrite before modifying previously built message. Causes modification to already "built" messages that should be immutable
- Fix Java reflection serialization of empty packed fields
- Refactoring java full runtime to reuse sub-message builders and prepare to migrate parsing logic from parse constructor to builder
- Move proto wireformat parsing functionality from the private "parsing constructor" to the Builder class
- Change the Lite runtime to prefer merging from the wireformat into mutable messages rather than building up a new immutable object before merging. This way results in fewer allocations and copy operations.
- Make message-type extensions merge from wire-format instead of building up instances and merging afterwards. This has much better performance.
- Fix TextFormat parser to build up recurring (but supposedly not repeated) sub-messages directly from text rather than building a new sub-message and merging the fully formed message into the existing field
- Fix bug in nested builder caching logic where cleared sub-field builders would remain dirty after a clear and build in a parent layer
- Add exemplar variants of the Java Any.is() and Any.unpack() methods
- Use bit-field int values in buildPartial to skip work on unset groups