In this CL I'd like to call existing C++ Protobuf API from the V0 Rust API. Since parts of the C++ API are defined inline and using (obviously) C++ name mangling, we need to create a "thunks.cc" file that:
1) Generates code for C++ API function we use from Rust
2) Exposes these functions without any name mangling (meaning using `extern "C"`)
In this CL we add Bazel logic to generate "thunks" file, compile it, and propagate its object to linking. We also add logic to protoc to generate this "thunks" file.
The protoc logic is rather rudimentary still. I hope to focus on protoc code quality in my followup work on V0 Rust API using C++ kernel.
PiperOrigin-RevId: 523479839
This turns out to be quite of a yak shave to be able to perfectly test both kernels without having to pass extra Blaze flags.
PiperOrigin-RevId: 521850709
In this CL we're adding the barebones infrastructure to generate Rust proto messages using UPB as a backend. The API is what we call a V0, not yet production-quality, not yet rigorously designed, just something to enable parallel work.
The interesting part of switching backend between UPB and C++ will come in a followup.
PiperOrigin-RevId: 517089760
The internal design is consistent with other <lang>_proto_library rules. rust_proto_library attaches rust_proto_library_aspect on its `deps` attribute. The aspect traverses the dependency, and when it visits proto_library (detected by ProtoInfo provider) it registers 2 actions:
1) to run protoc with Rust backend to emit gencode
2) to compile the gencode using Rustc
Action (2) gets the Rust proto runtime as an input as well.
Coming in a followup is support and test coverage for proto_library.deps.
PiperOrigin-RevId: 514521285
Marcel Hlopko
Jakob Buchgraber
Protobuf Team Bot