Changes Announced on October 2, 2024

Changes announced for Protocol Buffers on October 2, 2024.

The following sections cover planned breaking changes in the v30 release, expected in 2025 Q1. These describe changes as we anticipate them being implemented, but due to the flexible nature of software some of these changes may not land or may vary from how they are described in this topic.

Changes in C++

C++ will bump its major version from 5.29.x to 6.30.x.

Descriptor APIs

v30 will update return types in descriptor (such as full_name) to be absl::string_view. This opens up memory savings in descriptors.

v28 introduced the PROTOBUF_FUTURE_STRING_VIEW_RETURN_TYPE macro, which you can use in the meantime to enable the updated return type ahead of the breaking release. The v30 release will flip the default and remove the macro.

ctype Removed from FieldDescriptor Options

v30 will stop exposing the ctype from FieldDescriptor options. You can use the FieldDescriptor::cpp_string_type() API, added in the v28 release, in its place.

Replace CMake Submodules with Fetched Deps

v30 will remove submodules and switches to upb’s old CMake pattern of fetching dependencies.

If you use installed packages, you won’t be affected. It could break some CMake workflows.

Remove Deprecated APIs

v30 will remove the following public runtime APIs, which have been marked deprecated (such as ABSL_DEPRECATED) for at least one minor or major release and that are obsolete or replaced.

Arena::CreateMessage

API: Arena::CreateMessage

Replacement: Arena::Create

Arena::GetArena

API: Arena::GetArena

Replacement: value->GetArena()

RepeatedPtrField::ClearedCount

API: RepeatedPtrField::ClearedCount

Replacement: Migrate to Arenas (migration guide).

JsonOptions

API: JsonOptions

Replacement: JsonPrintOptions

Dropping C++14 Support

This release will drop C++ 14 as the minimum supported version and raise it to 17, as per the Foundational C++ Support matrix.

Per our policies, we do not consider this to be a breaking change.

Changes in JRuby

v30 will flip the default implementation for JRuby to FFI, which may be breaking for some JRuby users.

Note that this change doesn’t create a Ruby major version bump because JRuby is not officially supported.

Changes in Python

Python will bump its major version from 5.29.x to 6.30.x.

Dropping Python 3.8 Support

As per our official Python support policy, we will be dropping support for Python 3.8 and lower. This means the minimum supported Python version is 3.9.

Remove bazel/system_python.bzl Alias

v30 will remove the legacy bazel/system_python.bzl alias.

Remove direct references to system_python.bzl in favor of using protobuf_deps.bzl instead. Use python/dist/system_python.bzl where it was moved in v5.27.0 if you need a direct reference.

Field Setter Validation Changes

Python’s and upb’s field setters will be fixed in v30 to validate closed enums under edition 2023. Closed enum fields updated with invalid values will generate errors.

Remove Deprecated APIs

v30 will remove the following public runtime APIs, which have been marked deprecated for at least one minor or major release and are obsolete or replaced.

Reflection Methods

APIs: reflection.ParseMessage, reflection.MakeClass

Replacement: message_factory.GetMessageClass()

RPC Service Interfaces

APIs: service.RpcException, service.Service, service.RpcController, and service.RpcChannel

Replacement: Starting with version 2.3.0, RPC implementations should not try to build on these, but should instead provide code generator plugins which generate code specific to the particular RPC implementation.

MessageFactory and SymbolDatabase Methods

APIs: MessageFactory.GetPrototype, MessageFactory.CreatePrototype, MessageFactory.GetMessages, SymbolDatabase.GetPrototype, SymbolDatabase.CreatePrototype, and SymbolDatabase.GetMessages

Replacement: message_factory.GetMessageClass() and message_factory.GetMessageClassesForFiles().

GetDebugString

APIs: GetDebugString

Replacement:

No replacement. It’s only in Python C++ which is no longer released. It is not supported in pure Python or UPB.

Changes in Objective-C

This will be the first breaking release for Objective-C.

Objective-C will bump its major version from 3.x.x to 4.30.x.

Overhaul Unknown Field Handling APIs Deprecating Most of the Existing APIs

v30 will deprecate GPBUnknownFieldSet and replace it with GPBUnknownFields. The new type will preserve the ordering of unknown fields from the original input or API calls, to ensure any semantic meaning to the ordering is maintained when a message is written back out.

As part of this, the GPBUnknownField type also has its APIs changed, with almost all of the existing APIs becoming deprecated and new ones added.

Deprecated property APIs:

varintList
fixed32List
fixed64List
lengthDelimitedList
groupList

Deprecated modification APIs:

addVarint:
addFixed32:
addFixed64:
addLengthDelimited:
addGroup:

Deprecated initializer initWithNumber:.

New property APIs:

type
varint
fixed32
fixed64
lengthDelimited
group

This type will model a single field number in its value, rather than grouping all the values for a given field number. The APIs for creating new fields are the add* APIs on the GPBUnknownFields class.

v30 will also deprecate -[GPBMessage unknownFields]. In its place, there will be new APIs to extract and update the unknown fields of the message.

Remove Deprecated APIs

v30 will remove the following public runtime APIs, which have been marked deprecated for at least one minor or major release and are obsolete or replaced.

GPBFileDescriptor

API: -[GPBFileDescriptor syntax]

Replacement: Obsolete.

Replacement: Obsolete - Use GPBTextFormatForMessage(), which includes any unknown fields.

GPBUnknownFieldSet

API: GPBUnknownFieldSet

Replacement: GPBUnknownFields

GPBMessage unknownFields

API: GPBMessage unknownFields property

Replacement: -[GPBUnknownFields initFromMessage:], -[GPBMessage mergeUnknownFields:extensionRegistry:error:], and -[GPBMessage clearUnknownFields]

Remove Deprecated Runtime APIs for Old Gencode

This release will remove deprecated runtime methods that support the Objective-C gencode from before the 3.22.x release. The library will also issue a log message at runtime when old generated code is starting up.

API: +[GPBFileDescriptor allocDescriptorForClass:file:fields:fieldCount:storageSize:flags:]