C++
* Fix compiler warnings issue found in conformance_test_runner 8189 (8190)
* Fix MinGW-w64 build issues. (8286)
* [Protoc] C++ Resolved an issue where NO_DESTROY and CONSTINIT are in incorrect order (8296)
* Fix PROTOBUF_CONSTINIT macro redefinition (8323)
* Delete StringPiecePod (8353)
* Fix gcc error: comparison of unsigned expression in '>= 0' is always … (8309)
* Fix cmake install on iOS (8301)
* Create a CMake option to control whether or not RTTI is enabled (8347)
* Fix endian.h location on FreeBSD (8351)
* Refactor util::Status (8354)
* Make util::Status more similar to absl::Status (8405)
* Fix -Wsuggest-destructor-override for generated C++ proto classes. (8408)
* Refactor StatusOr and StringPiece (8406)
* Refactor uint128 (8416)
* The ::pb namespace is no longer exposed due to conflicts.
* Allow MessageDifferencer::TreatAsSet() (and friends) to override previous
calls instead of crashing.
* Reduce the size of generated proto headers for protos with `string` or
`bytes` fields.
* Move arena() operation on uncommon path to out-of-line routine
* For iterator-pair function parameter types, take both iterators by value.
* Code-space savings and perhaps some modest performance improvements in
RepeatedPtrField.
* Eliminate nullptr check from every tag parse.
* Remove unused _$name$_cached_byte_size_ fields.
* Serialize extension ranges together when not broken by a proto field in the
middle.
* Do out-of-line allocation and deallocation of string object in ArenaString.
* Streamline ParseContext::ParseMessage<T> to avoid code bloat and improve
performance.
* New member functions RepeatedField::Assign, RepeatedPtrField::{Add, Assign}.
* Fix undefined behavior warning due to innocuous uninitialization of value
on an error path.
* Avoid expensive inlined code space for encoding message length for messages
>= 128 bytes and instead do a procedure call to a shared out-of-line routine.
* util::DefaultFieldComparator will be final in a future version of protobuf.
Subclasses should inherit from SimpleFieldComparator instead.
C
* Add .NET 5 target and improve WriteString performance with SIMD (8147)
Java
* deps: update JUnit and Truth (8319)
* Detect invalid overflow of byteLimit and return InvalidProtocolBufferException as documented.
* Exceptions thrown while reading from an InputStream in parseFrom are now
included as causes.
* Support potentially more efficient proto parsing from RopeByteStrings.
* Clarify runtime of ByteString.Output.toStringBuffer().
* Added UnsafeByteOperations to protobuf-lite (8426)
JavaScript
* Make Any.pack() chainable.
Python
* Fix some constness / char literal issues being found by MSVC standard conforming mode (8344)
* Switch on "new" buffer API (8339)
* Enable crosscompiling aarch64 python wheels under dockcross manylinux docker image (8280)
* Fixed a bug in text format where a trailing colon was printed for repeated field.
* When TextFormat encounters a duplicate message map key, replace the current
one instead of merging.
Objective-C
* Move the class map to a CFDictionary. (8328)
PHP
* read_property() handler is not supposed to return NULL (8362)
* Changed parameter type from long to integer (7613)
* fix: README supported PHP version for C extension (8236)
Ruby
* Fixed quadratic memory usage when appending to arrays. (8364)
* Fixed memory leak of Ruby arena objects. (8461)
* Add support for proto3 json_name in compiler and field definitions. (8356)
Other
* Some doc on AOT compilation and protobuf (8294)
* [CMake] Ability to pass options to protoc executable from cmake (8374)
* Add --fatal_warnings flag to treat warnings as errors (8131)
* [bazel] Remove deprecated way to depend on googletest (8396)
* add error returns missing from protoc to prevent it from exiting with… (8409)