Scaffold Swift-implemented drop-in replacement for libbluetooth.so.3

.github/workflows/cmake.yml

@@ -0,0 +1,62 @@
+name: CMake
+
+on: [push]
+
+jobs:
+
+  # Verifies the CMake packaging path, which is what actually produces
+  # the installable libbluetooth.so.3: soname, symbol versioning and the
+  # export list are not expressible in Package.swift, so SwiftPM's build
+  # of the same sources proves nothing about the shipped artifact.
+  #
+  # This is also the only job that runs check-exports, the assertion that
+  # the library exports exactly the reference's symbol set — the one
+  # check that would catch the drop-in premise breaking.
+  cmake:
+    name: CMake
+    runs-on: ubuntu-latest
+    # noble, not jammy like the Swift workflow: CMakeLists.txt requires
+    # CMake 3.26+ and jammy's apt carries only 3.22. noble ships 3.28.
+    # 6.3 because the C ABI is bound with `@c`, which 6.2 rejects.
+    container: swift:6.3.3-noble
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v4
+    # The shared object links the non-socket half of the C ABI out of
+    # PureSwift/Bluetooth's own CMakeLists, so that has to be checked out
+    # too — pinned to the same version Package.swift depends on, so the
+    # two halves cannot drift apart in CI.
+    - name: Checkout PureSwift/Bluetooth
+      uses: actions/checkout@v4
+      with:
+        repository: PureSwift/Bluetooth
+        ref: "8.1.0"
+        path: Bluetooth
+    - name: Swift Version
+      run: swift --version
+    # python3 as well: the swift containers don't ship it, and the
+    # configure step runs the stub/symbol generators (scripts/*.py)
+    # through find_package(Python3), which is REQUIRED.
+    - name: Install CMake, Ninja and Python
+      run: apt-get update && apt-get install -y cmake ninja-build python3
+    # $GITHUB_WORKSPACE (the runtime variable), not ${{ github.workspace }}
+    # (the expression): in a container job the expression expands to the
+    # host path (/home/runner/work/...), which does not exist inside the
+    # container, where the workspace is mounted at /__w/... instead. The
+    # variable is set by the runner in the container's environment and
+    # resolves to the mounted path.
+    - name: Configure
+      run: >
+        cmake -B build -G Ninja
+        -DCMAKE_BUILD_TYPE=Release
+        -DBLUETOOTH_PACKAGE_PATH="${GITHUB_WORKSPACE}/Bluetooth"
+    - name: Build
+      run: cmake --build build
+    - name: Check exported symbols
+      run: cmake --build build --target check-exports
+    # Installing is cheap and catches a broken install rule, which would
+    # otherwise only surface when someone tries to package the library.
+    - name: Install
+      run: cmake --install build --prefix "${GITHUB_WORKSPACE}/install"
+    - name: Show installed layout
+      run: find "${GITHUB_WORKSPACE}/install" -type f -o -type l

.github/workflows/swift.yml

@@ -4,10 +4,39 @@ on: [push]
 
 jobs:
 
-    linux-swift:
-        name: Linux
+    # The toolchain floor is 6.2, not the 6.0.2 this used to pin:
+    # PureSwift/Bluetooth 8.1.0 declares swift-tools-version:6.2, so an
+    # older toolchain cannot parse the dependency's manifest and fails
+    # during resolution, before anything is compiled.
+    linux:
+        name: Linux (${{ matrix.container }}, ${{ matrix.config }})
+        strategy:
+          # One failing cell shouldn't hide the others' results — which
+          # toolchain/configuration combinations fail is the whole point
+          # of running a matrix.
+          fail-fast: false
+          matrix:
+            container: ["swift:6.2.3", "swift:6.3.3"]
+            config: ["debug", "release"]
         runs-on: ubuntu-latest
-        container: swift:6.0.2-jammy
+        container: ${{ matrix.container }}-jammy
+        steps:
+        - name: Checkout
+          uses: actions/checkout@v4
+        - name: Swift Version
+          run: swift --version
+        - name: Build
+          run: swift build -c ${{ matrix.config }}
+        - name: Test
+          run: swift test -c ${{ matrix.config }}
+
+    # Coverage runs once rather than per matrix cell: the report is a
+    # property of the source, not of the toolchain, and one upload keeps
+    # the artifact names unambiguous.
+    coverage:
+        name: Coverage
+        runs-on: ubuntu-latest
+        container: swift:6.3.3-jammy
         permissions:
           contents: read
           code-quality: write # required by actions/upload-code-coverage
@@ -16,10 +45,6 @@ jobs:
           uses: actions/checkout@v4
         - name: Swift Version
           run: swift --version
-        - name: Build (Debug)
-          run: swift build -c debug
-        - name: Build (Release)
-          run: swift build -c release
         - name: Test (Debug)
           run: swift test --configuration debug --enable-code-coverage
         - name: Archive Build artifacts
@@ -48,3 +73,38 @@ jobs:
             name: code-coverage
             path: .build/coverage/
             if-no-files-found: error
+
+    # The C ABI targets are excluded from the package unless
+    # SWIFTPM_BLUETOOTH_CABI=1, so none of the jobs above compile a line
+    # of them — this is the only SwiftPM coverage the drop-in library
+    # gets.
+    #
+    # 6.3 only, unlike the matrix above: the boundary functions are bound
+    # to the vendored declarations with `@c`, which 6.2 rejects as an
+    # unknown attribute.
+    c-abi:
+        name: C ABI (${{ matrix.config }})
+        strategy:
+          fail-fast: false
+          matrix:
+            config: ["debug", "release"]
+        runs-on: ubuntu-latest
+        container: swift:6.3.3-jammy
+        env:
+          SWIFTPM_BLUETOOTH_CABI: "1"
+        steps:
+        - name: Checkout
+          uses: actions/checkout@v4
+        - name: Swift Version
+          run: swift --version
+        - name: Build
+          run: swift build -c ${{ matrix.config }}
+        - name: Test
+          run: swift test -c ${{ matrix.config }}
+        # The differential drivers are C programs linked twice, once
+        # against the reference library and once against ours, so both a
+        # C compiler and the real libbluetooth.so.3 have to be present.
+        - name: Install conformance prerequisites
+          run: apt-get update && apt-get install -y gcc libbluetooth3
+        - name: Differential conformance
+          run: Conformance/compare.sh "$(swift build -c ${{ matrix.config }} --show-bin-path)/libBluetoothLinuxABI.so"