Add custom bindings glue code to the STL, starting with `std::string_view`.

This change makes `std::string_view` usable, in a hacky way, from Rust: you can convert a Rust `&'static str` or `&'static [u8]` to a C++ `std::string_view`, and vice versa.

This is not *sound*:

1. `string_view` doesn't necessarily obey Rust's aliasing rules. (This is common with all our bindings atm.)
2. `string_view` doesn't currently have lifetime params; we just kinda assume static for now. (This makes Rust code that takes in a string_view about as safe as C++ code that does, to be fair!)

Overall, not the worst. And the result is that you really can call APIs that take and return `string_view`. Well, probably.

### How does it work?

This reuses `extra_rs_srcs` so that the STL can have additional methods/trait impls. In theory the same mechanism should also work for providing extra sources to any target, but that requires more plumbing / aspect hints / whatever. At the moment this does not expose `extra_rs_srcs` to anything except the STL. But presumably that's an obvious next step, especially if we want to do similar things to support Abseil, and so on.

PiperOrigin-RevId: 478948595
24 files changed
tree: 752376b690f7627a7d7ddcdd771324f3e72c4573
  1. .bazelci/
  2. bazel/
  3. cc_bindings_from_rs/
  4. cc_import/
  5. cc_template/
  6. common/
  7. docs/
  8. lifetime_analysis/
  9. lifetime_annotations/
  10. migrator/
  11. nullability_verification/
  12. rs_bindings_from_cc/
  13. .bazelrc
  14. .gitignore
  15. BUILD
  16. Cargo.Bazel.lock
  17. CODE_OF_CONDUCT
  18. CONTRIBUTING
  19. LICENSE
  20. README.md
  21. WORKSPACE
README.md

Crubit: C++/Rust Bidirectional Interop Tool

Build status

Extremely experimental interop tooling for C++ and Rust.

Please don‘t use, this is an experiment and we don’t yet know where will it take us. There will be breaking changes without warning. Unfortunately, we can't take contributions at this point.

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