C++: Add BMN CI and developer guidance

Run Cargo and Bazel checks when the build-mode-none extractor changes, integrate its Rust lint into pre-commit, and document the standalone development workflow.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: paldepind

.github/workflows/cpp-bmn.yml

@@ -0,0 +1,55 @@
+name: C/C++ build mode none extractor
+
+on:
+  pull_request:
+    paths:
+      - "cpp/extractor/bmn/**"
+      - "misc/bazel/3rdparty/cpp_bmn_deps/**"
+      - "misc/bazel/3rdparty/cpp_bmn_deps_extension.bzl"
+      - "misc/bazel/3rdparty/update_cpp_bmn_deps.sh"
+      - "misc/bazel/3rdparty/BUILD.bazel"
+      - "misc/bazel/rust.bzl"
+      - "MODULE.bazel"
+      - ".github/workflows/cpp-bmn.yml"
+  push:
+    branches:
+      - main
+      - "rc/*"
+    paths:
+      - "cpp/extractor/bmn/**"
+      - "misc/bazel/3rdparty/cpp_bmn_deps/**"
+      - "misc/bazel/3rdparty/cpp_bmn_deps_extension.bzl"
+      - "misc/bazel/3rdparty/update_cpp_bmn_deps.sh"
+      - "misc/bazel/3rdparty/BUILD.bazel"
+      - "misc/bazel/rust.bzl"
+      - "MODULE.bazel"
+      - ".github/workflows/cpp-bmn.yml"
+
+permissions:
+  contents: read
+
+jobs:
+  cargo:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: cpp/extractor/bmn
+    steps:
+      - uses: actions/checkout@v5
+      - name: Check formatting
+        run: cargo fmt --check
+      - name: Check
+        run: cargo check
+      - name: Clippy
+        run: cargo clippy -- -D warnings
+      - name: Test
+        run: cargo test
+
+  bazel:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v5
+      - name: Build
+        run: bazel build //cpp/extractor/bmn:bmn
+      - name: Test
+        run: bazel test //cpp/extractor/bmn:tests

.pre-commit-config.yaml

@@ -85,3 +85,10 @@ repos:
         language: system
         entry: python3 rust/lint.py
         pass_filenames: false
+
+      - id: cpp-bmn-lint
+        name: Run fmt and clippy on C/C++ BMN Rust code
+        files: ^cpp/extractor/bmn/(.*rs|Cargo.toml)$
+        language: system
+        entry: cpp/extractor/bmn/lint --check
+        pass_filenames: false

cpp/extractor/bmn/README.md

@@ -1,33 +1,26 @@
-# C/C++ BMN
+# C/C++ build mode none extractor
 
-## Running in a container
+This directory contains the C/C++ build mode none (BMN) extractor. It scans a
+source tree and heuristically constructs extraction commands without observing
+a build.
 
-When dependency installation is enabled BMN assumes that it's running on Ubuntu
-and runs `sudo apt-get` to install packages.
+Run the Rust checks with:
 
-The `create-database-in-container.sh` script makes it possible to create
-databases in an Ubuntu container. This makes it possible to create databases on
-non-Ubuntu OSes and without dependencies being installed globally on the host
-OS.
-
-### Prerequisites
-
-- **SSH agent with GitHub access**: The container build clones the `semmle-code`
-  repository via SSH. Ensure your SSH agent is running and has a key with access
-  to `git@github.com:github/semmle-code.git`:
-  ```sh
-  eval $(ssh-agent)
-  ssh-add ~/.ssh/your_github_key
-  ```
+```sh
+./lint --check
+cargo test
+```
 
-### Usage
+Build and test the Bazel target from the repository root with:
 
 ```sh
-./container/create-database-in-container.sh ~/projects/my-cpp-project /tmp/my-database
+bazel build //cpp/extractor/bmn:bmn
+bazel test //cpp/extractor/bmn:tests
 ```
 
-To enable automatic dependency installation (runs `apt-get` inside the container):
+After changing Cargo dependencies, regenerate the checked-in Bazel dependency
+definitions with:
 
 ```sh
-./container/create-database-in-container.sh --install-dependencies ~/projects/my-cpp-project /tmp/my-database
+misc/bazel/3rdparty/update_cpp_bmn_deps.sh
 ```