Protocol Compiler
* [experimental] Singular, non-message typed fields in proto3 now support
presence tracking. This is enabled by adding the "optional" field label and
passing the `--experimental_allow_proto3_optional` flag to protoc.
* For usage info, see [docs/field_presence.md](docs/field_presence.md).
* During this experimental phase, code generators should update to support
proto3 presence, see [docs/implementing_proto3_presence.md](docs/implementing_proto3_presence.md) for instructions.
* Allow duplicate symbol names when multiple descriptor sets are passed on
the command-line, to match the behavior when multiple .proto files are passed.
* Deterministic `protoc --descriptor_set_out` (7175)
C++
* [experimental] Added proto3 presence support.
* New descriptor APIs to support proto3 presence.
* Fix for 7463 in -rc1 (core dump mixing optional and singular fields in proto3)
* Enable Arenas by default on all .proto files.
* Documented that users are not allowed to subclass Message or MessageLite.
* Mark generated classes as final; inheriting from protos is strongly discouraged.
* Add stack overflow protection for text format with unknown fields.
* Add accessors for map key and value FieldDescriptors.
* Add FieldMaskUtil::FromFieldNumbers().
* MessageDifferencer: use ParsePartial() on Any fields so the diff does not
fail when there are missing required fields.
* ReflectionOps::Merge(): lookup messages in the right factory, if it can.
* Added Descriptor::WellKnownTypes enum and Descriptor::well_known_type()
accessor as an easier way of determining if a message is a Well-Known Type.
* Optimized RepeatedField::Add() when it is used in a loop.
* Made proto move/swap more efficient.
* De-virtualize the GetArena() method in MessageLite.
* Improves performance of json_stream_parser.cc by factor 1000 (7230)
* bug: 7076 undefine Windows OUT and OPTIONAL macros (7087)
* Fixed a bug in FieldDescriptor::DebugString() that would erroneously print
an "optional" label for a field in a oneof.
* Fix bug in parsing bool extensions that assumed they are always 1 byte.
* Fix off-by-one error in FieldOptions::ByteSize() when extensions are present.
* Clarified the comments to show an example of the difference between
Descriptor::extension and DescriptorPool::FindAllExtensions.
* Add a compiler option 'code_size' to force optimize_for=code_size on all
protos where this is possible.
Java
* [experimental] Added proto3 presence support.
* Fix for 7480 in -rc1 ("TextFormat and JsonFormat ignore experimental proto3 optional enums")
* Fix for 7505 in -rc1 (" toString() returns incorrect ascii when there are duplicate keys in a map")
* Mark java enum _VALUE constants as Deprecated if the enum field is deprecated
* reduce <clinit> size for enums with allow_alias set to true.
* Sort map fields alphabetically by the field's key when printing textproto.
* TextFormat.merge() handles Any as top level type.
* Throw a descriptive IllegalArgumentException when calling
getValueDescriptor() on enum special value UNRECOGNIZED instead of
ArrayIndexOutOfBoundsException.
* Fixed an issue with JsonFormat.printer() where setting printingEnumsAsInts()
would override the configuration passed into includingDefaultValueFields().
* Implement overrides of indexOf() and contains() on primitive lists returned
for repeated fields to avoid autoboxing the list contents.
* Add overload to FieldMaskUtil.fromStringList that accepts a descriptor.
* [bazel] Move Java runtime/toolchains into //java (7190)
Python
* [experimental] Added proto3 presence support.
* [experimental] fast import protobuf module, only works with cpp generated code linked in.
* Truncate 'float' fields to 4 bytes of precision in setters for pure-Python
implementation (C++ extension was already doing this).
* Fixed a memory leak in C++ bindings.
* Added a deprecation warning when code tries to create Descriptor objects
directly.
* Fix unintended comparison between bytes and string in descriptor.py.
* Avoid printing excess digits for float fields in TextFormat.
* Remove Python 2.5 syntax compatibility from the proto compiler generated _pb2.py module code.
* Drop 3.3, 3.4 and use single version docker images for all python tests (7396)
JavaScript
* Fix js message pivot selection (6813)
PHP
* Persistent Descriptor Pool (6899)
* Implement lazy loading of php class for proto messages (6911)
* Correct return in Any.unpack docblock (7089)
* Ignore unknown enum value when ignore_unknown specified (7455)
Ruby
* [experimental] Implemented proto3 presence for Ruby. (7406)
* Stop building binary gems for ruby <2.5 (7453)
* Fix for wrappers with a zero value (7195)
* Fix for JSON serialization of 0/empty-valued wrapper types (7198)
* Call "Classnew" over rb_class_new_instance in decoding (7352)
* Build extensions for Ruby 2.7 (7027)
* assigning 'nil' to submessage should clear the field. (7397)
C
* [experimental] Add support for proto3 presence fields in C (7382)
* Cleanup various bits of Google.Protobuf (6674)
* Fix conformance test failures for Google.Protobuf (6910)
* Fix latest ArgumentException for C extensions (6938)
* Remove unnecessary branch from ReadTag (7289)
* Enforce recursion depth checking for unknown fields (7132)
* Mark GetOption API as obsolete and expose the "GetOptions()" method
on descriptors instead (7491)
* Remove Has/Clear members for C message fields in proto2 (7429)
Objective-C
* [experimental] ObjC Proto3 optional support (7421)
* Block subclassing of generated classes (7124)
* Use references to Obj C classes instead of names in descriptors. (7026)
* Revisit how the WKTs are bundled with ObjC. (7173)
Other
* Add a proto_lang_toolchain for javalite (6882)
* [bazel] Update gtest and deprecate //external:{gtest,gtest_main} (7237)
* Add application note for explicit presence tracking. (7390)
* Howto doc for implementing proto3 presence in a code generator. (7407)