It is common to want to match only a subset of fields in large protobufs, and doing that in rust right now requires manually clearing out the fields in the `actual` message that we don't care about. This is a pain, and a worse experience when compared to C++.
Like in C++, when doing partial matching, only fields set in the expected protobuf message are compared, while extra fields set only in the actual message are ignored.
When using the C++ kernel we leverage `proto2::util::MessageDifferencer`, and for the UPB kernel we use the `kUpb_CompareOption_Partial` option.
PiperOrigin-RevId: 964125682
This code makes use of some Rust features that are not supported in Rust 1.85 (our currently supported version), so we cannot enable the codegen for this feature yet.
This CL introduces support for [Protobuf Extensions](https://engdoc.corp.google.com/eng/doc/devguide/proto/programming-guides/proto2.html#extensions) to the Rust Protobuf library, a key feature for full Proto2 API parity.
Key changes include:
1. **Code Generation:**
* Added `compiler/rust/extension.cc` and `extension.h` to handle the generation of Rust code for extension definitions.
* Updated `generator.cc` and `message.cc` to invoke extension generation for both top-level and nested extensions.
* Generates `ExtensionId` constants for each extension.
2. **Runtime API (`rust/extension.rs`):**
* Introduced the generic `ExtensionId<Extendee, T>` type to identify and type-check extensions.
* Defined traits for extension operations: `ExtHas`, `ExtGet`, `ExtSet`, `ExtClear`, and `ExtGetMut`.
* Implemented methods on `ExtensionId` that dispatch to the trait implementations provided by the active kernel.
3. **Kernel Implementations:**
* **C++ Kernel (`rust/cpp_kernel/extension.rs`):** Implemented extension traits by calling into new C++ FFI functions (defined in `rust/cpp_kernel/extension.cc`) that interact with the C++ `ExtensionSet`.
* **UPB Kernel (`rust/upb_kernel/extension.rs`):** Implemented extension traits using UPB's MiniTable-based extension API. Extension MiniTables are registered at static initialization time using the `linkme` crate.
4. **Build System:**
* Updated `protobuf/rust/BUILD` and `protobuf/compiler/rust/BUILD` to include new files.
* Added a dependency on `//third_party/rust/linkme/v0_3` for the UPB kernel's extension registration.
5. **Testing:**
* Added `test/extensions.proto` and `test/extensions_separate_file.proto` to define various extension types.
* Added `test/shared/extensions_test.rs` with comprehensive tests covering presence, getters, setters, defaults, nested extensions, submessage extensions, repeated extensions, serialization, and `MergeFrom`.
This change enables Rust users to define and interact with Protobuf extensions in a type-safe manner, compatible with both the C++ and UPB runtimes.
PiperOrigin-RevId: 896506594
This change moves the `OwnedMessageInterop`, `MessageViewInterop`, and `MessageMutInterop` traits from `codegen_traits.rs` into new `interop.rs` files within both the `cpp_kernel` and `upb_kernel` directories.
The `KernelMessage`, `KernelMessageView`, and `KernelMessageMut` traits in each kernel's `message.rs` are updated to include the respective kernel-specific interop traits. This ensures that the interop functionality is tied to the specific kernel implementation.
The `shared.rs` module now re-exports the interop traits from `crate::__internal::runtime::interop`, which will resolve to the correct kernel's interop module.
It would be possible to take this farther by making the interop traits return strongly typed pointers to `upb_Message*` and `proto2::MessageLite*` instead of `c_void`, but that would be a breaking change.
PiperOrigin-RevId: 892470084
MessageMutInner was Copy+Clone, which had been convenient for some internal use. But, with them being .into() SomeMessageMut this was a potential footgun, since it was very easy to into() the same one twice which would be formally unsound if it was reachable (including that you could send each of them to a different thread and concurrently modify them).
As these were implementation detail types this is only a defensive fix and no actual soundness issues were identified.
PiperOrigin-RevId: 888615057
This CL contains no functional change, it is a pure splitting of the existing files.
I elected to move the C++ kernel files to `cpp_kernel/` which already contained the C++ API for the C++ kernel. Unfortunately this required removing the existing `third_party/protobuf/rust/cpp_kernel/BUILD` file, because, the Rust parts of the cpp kernel have circular dependencies with the shared code in `third_party/protobuf/rust`.
PiperOrigin-RevId: 886884124
