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bazel / crubit / 240782f5d5cae15c48fb55d9ca68e02ea68cf3ee
commit240782f5d5cae15c48fb55d9ca68e02ea68cf3ee[log] [tgz]
authorDevin Jeanpierre <jeanpierreda@google.com>Fri Jun 28 15:14:10 2024 -0700
committerCopybara-Service <copybara-worker@google.com>Fri Jun 28 15:15:17 2024 -0700
tree4ca9466eca9107cd7494396a63774466f931be30
parente9d8361f51ad466b9c777d1f05c8884ccdef1f89 [diff]
Disable Crubit on grpc and targets that disable header parsing.

This allows Crubit to work on targets that depend on grpc, as long as they do not transitively include the headers. So, that's a workaround, at least.

This is not "strictly correct": a target might disable header parsing because it has a bad header in `srcs`, which isn't relevant to Crubit which only reads `hdrs`. However, it's almost certainly (also) broken in `srcs`. If ever we need to enable Crubit on a target that has a broken srcs header, but not a broken.

As far as grpc itself goes, we just don't correctly handle those headers right now. If grpc shows up anywhere in the transitive dependency graph, it breaks Crubit. That's a problem, and this works around that by disabling Crubit.

(Similarly for openssl.)

In the longer term, we should not have the grpc denylist, and I've filed b/349750606 and b/349750659 to track some of this work.

PiperOrigin-RevId: 647810496
Change-Id: Ic75dd706304d4373afa6c565633dd9c397b042cc
4 files changed
tree: 4ca9466eca9107cd7494396a63774466f931be30
  1. .bazelci/
  2. bazel/
  3. cc_bindings_from_rs/
  4. common/
  5. docs/
  6. examples/
  7. features/
  8. lifetime_analysis/
  9. lifetime_annotations/
  10. migrator/
  11. nullability/
  12. rs_bindings_from_cc/
  13. support/
  14. .bazelrc
  15. .gitignore
  16. BUILD
  17. Cargo.lock
  18. CODE_OF_CONDUCT
  19. CONTRIBUTING
  20. LICENSE
  21. MODULE.bazel
  22. README.md
  23. WORKSPACE.bzlmod
README.md

Crubit: C++/Rust Bidirectional Interop Tool

Build status

NOTE: Crubit currently expects deep integration with the build system, and is difficult to deploy to environments dissimilar to Google's monorepo. We do not have our tooling set up to accept external contributions at this time.

Crubit is a bidirectional bindings generator for C++ and Rust, with the goal of integrating the C++ and Rust ecosystems.

Status

Support for calling FFI-friendly C++ from Rust is in progress.

Support for calling Rust from C++ will arrive in 2024H2.

Example

Consider the following C++ function:

extern "C" bool IsGreater(int lhs, int rhs);

This function, if present in a header file which is processed by Crubit, becomes callable from Rust as if it were defined as:

pub fn IsGreater(lhs: ffi::c_int, rhs: ffi::c_int) -> bool {...}

Note: There are some temporary restrictions on the API shape. For example, functions that are not extern "C", or that accept a type like std::string, can't be called from Rust directly via Crubit. These restrictions will be relaxed over time.

Getting Started

Here are some resources for getting started with Crubit:

  • Rust Bindings for C++ Libraries is a detailed walkthrough on how to use C++ from Rust using Crubit.

  • The examples/cpp/ directory has copy-pastable examples of calling C++ from Rust, together with snapshots of what the generated Rust interface looks like.

Building Crubit

$ apt install clang lld bazel
$ git clone git@github.com:google/crubit.git
$ cd crubit
$ bazel build --linkopt=-fuse-ld=/usr/bin/ld.lld //rs_bindings_from_cc:rs_bindings_from_cc_impl

Using a prebuilt LLVM tree

$ git clone https://github.com/llvm/llvm-project
$ cd llvm-project
$ CC=clang CXX=clang++ cmake -S llvm -B build -DLLVM_ENABLE_PROJECTS='clang' -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=install
$ cmake --build build -j
$ # wait...
$ cmake --install build
$ cd ../crubit
$ LLVM_INSTALL_PATH=../llvm-project/install bazel build //rs_bindings_from_cc:rs_bindings_from_cc_impl