Changes Announced on June 27, 2025

Changes announced for Protocol Buffers on June 27, 2025.

Edition 2024

We are planning to release Protobuf Editions in 32.x in Q3 2025.

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.

More documentation on Edition 2024 will be published in Feature Settings for Editions, including information on migrating from Edition 2023.

Changes to Existing Features

This section details any existing features whose default settings will change in Edition 2024.

C++ string_type

The default for string_type feature, originally released in Edition 2023, will change from STRING to VIEW in Edition 2024.

See features.(pb.cpp).string_type and String View APIs for more information on this feature and its feature values.

New Features

This section details any new features that will be introduced in Edition 2024.

enforce_naming_style

feature.enforce_naming_style enables strict naming style enforcement to ensure protos are round-trippable by default with a feature value to opt-out to use legacy naming style.

default_symbol_visibility

This feature controls whether the default symbol visibility of importable symbols (such as messages and enums) is either:

  • export: referenceable from other protos via import statements
  • local: un-referenceable outside of current file

The default feature value EXPORT_TOP_LEVEL in Edition 2024 ensures top-level symbols are export by default, whereas nested symbols are local by default.

This can be used along with the export and local keywords to explicitly annotate symbol visibility, also added in Edition 2024.

Symbol visibility only controls which symbols can be imported from other proto files, but does not affect code-generation.

C++: enum_name_uses_string_view

Previously, all generated enum types provide the following function to obtain the label out of an enum value, which has significant overhead to construct the std::string instances at runtime:

const std::string& Foo_Name(int);

The default feature value in Edition 2024 instead migrates this signature to return absl::string_view to allow for better storage decoupling and potential memory/CPU savings.

absl::string_view Foo_Name(int);

Users should migrate their code to handle the new return-type following the migration guide.

See String View APIs for more information.

Java: nest_in_file_class

This feature controls whether the Java generator will nest the generated class in the Java generated file class.

The default value in Edition 2024 generates classes in their own files by default, which is also the default behavior of the previous java_multiple_files = true file option. This replaces java_multiple_files which is removed in Edition 2024.

The default outer classname is also updated to always be the camel-cased .proto filename suffixed with Proto by default (for example, foo/bar_baz.proto -> BarBazProto). You can override this using the java_outer_classname file option and replace the pre-Edition 2024 default of BarBaz or BarBazOuterClass depending on the presence of conflicts.

Java: large_enum

This feature allows creation of large Java enums, extending beyond the enum limit due to standard constant limits imposed by the Java language.

Creation of large enums is not enabled by default, but you can explicitly enable it using this feature. Note that this feature replicates enum-like behavior but has some notable differences (for example, switch statements are not supported).

Grammar Changes

import option

Edition 2024 adds support for option imports using the syntax import option.

Unlike normal import statements, option imports import only custom options defined in a .proto file, without importing other symbols.

This means that messages and enums are excluded from the option import. In the following example, the Bar message cannot be used as a field type in foo.proto, but options with type Bar can still be set.

Option imports must also come after any other import statements.

Example:

// bar.proto
edition = "2024";

import "google/protobuf/descriptor.proto";

message Bar {
  bool bar = 1;
}

extend proto2.FileOptions {
  bool file_opt1 = 5000;
  Bar file_opt2 = 5001;
}

// foo.proto:
edition = "2024";

import option "bar.proto";

option (file_opt1) = true;
option (file_opt2) = {bar: true};

message Foo {
  // Bar bar = 1; // This is not allowed
}

Option imports do not require generated code for its symbols and thus must be provided as option_deps in proto_library instead of deps. This avoids generating unreachable code.

proto_library(
  name = "foo",
  srcs = ["foo.proto"],
  option_deps = [":custom_option"]
)

Option imports and option_deps are strongly recommended when importing protobuf language features and other custom options to avoid generating unnecessary code.

option_deps requires Bazel 8 or later since the native.proto_library in Bazel 7 does not support this.

This also replaces import weak, which is removed in Edition 2024.

export / local Keywords

export and local keywords are added in Edition 2024 as modifiers for the symbol visibility of importable symbols, from the default behavior specified by the default_symbol_visibility feature.

This controls which symbols can be imported from other proto files, but does not affect code-generation.

In Edition 2024, these can be set on all message and enum symbols by default. However, some values of the default_symbol_visibility feature further restrict which symbols are exportable.

Example:

// Top-level symbols are exported by default in Edition 2024
local message LocalMessage {
  // Nested symbols are local by default in Edition 2024
  export enum ExportedNestedEnum {
    UNKNOWN_EXPORTED_NESTED_ENUM_VALUE = 0;
  }
}

“import weak” and weak Field Option

Weak imports are no longer allowed as of Edition 2024.

Most users previously relying on import weak to declare a “weak dependency” to import custom options without generated code for C++ and Go should instead migrate to use import option instead.

ctype Field Option

ctype field option is no longer allowed as of Edition 2024. Use the features.(pb.cpp).string_type feature, instead.

java_multiple_files File Option

The java_multiple_files file option is removed in Edition 2024 in favor of the new features.nest_in_file_class Java feature.