Bazel support: Replace `PREBUILT_LLVM_PATH` with `LLVM_INSTALL_PATH`.

Pre-built LLVM+Clang libraries+headers can be found either at:

1. LLVM's source path (`PREBUILT_LLVM_PATH`) *and* build path
   `"${PREBUILT_LLVM_PATH}/${CMAKE_BUILD_DIR}"` taken together, or

2. LLVM's install path (`LLVM_INSTALL_PATH`)

This CL switches from the former to the latter approach because:

1. Bazel's `glob` doesn't like dealing with `..` or absolute paths
   (and Chromium places LLVM's build directory outside of LLVM's
   source directory).

2. It slightly simplifies Crubit's BUILD files (see the changes
   in this CL).

PiperOrigin-RevId: 451898842
3 files changed
tree: 0103c4d45c2587cdb4a5b6208dd99bd05a6f4f2c
  1. .bazelci/
  2. bazel/
  3. cc_template/
  4. common/
  5. docs/
  6. lifetime_analysis/
  7. lifetime_annotations/
  8. migrator/
  9. rs_bindings_from_cc/
  10. .bazelrc
  11. .gitignore
  12. BUILD
  13. Cargo.Bazel.lock
  14. CODE_OF_CONDUCT
  15. CONTRIBUTING
  16. LICENSE
  17. README.md
  18. WORKSPACE
README.md

Crubit: C++/Rust Bidirectional Interop Tool

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