ci: Upgrade to LLVM Clang 16 to support C++20 features on macOS 13 and 14; Ensure LLVM Toolchain Consistency; Add macOS 15 to GitHub workflow.

.github/workflows/clp-core-build-macos.yaml

@@ -41,9 +41,12 @@ jobs:
   build-macos:
     strategy:
       matrix:
-        runner: ["macos-13", "macos-14"]
+        os:
+          - "macos-13"
+          - "macos-14"
+          - "macos-15"
         use_shared_libs: [true, false]
-    runs-on: "${{matrix.runner}}"
+    runs-on: "${{matrix.os}}"
     steps:
       - uses: "actions/checkout@v4"
         with:
@@ -67,14 +70,35 @@ jobs:
       - run: "task deps:core"
         shell: "bash"
 
+      - if: "'macos-13' == matrix.os || 'macos-14' == matrix.os"
+        name: "Upgrade the default AppleClang to LLVM Clang for C++20 features"
+        shell: "bash"
+        run: |
+          brew install llvm@16
+          echo "USE_LLVM_COMPILER=true" >> $GITHUB_ENV
+          echo "LLVM_INSTALL_BINDIR=$(brew --prefix llvm@16)/bin" >> $GITHUB_ENV
+
       - name: "Build CLP-core and run unit tests"
         shell: "bash"
         working-directory: "./components/core"
         # NOTE: We omit the Stopwatch tests since GH's macOS runner is too slow
         run: >-
+          $(
+          [[ "${{ env.USE_LLVM_COMPILER }}" == "true" ]]
+          && echo
+          "env"
+          "CC=${{ env.LLVM_INSTALL_BINDIR }}/clang"
+          "CXX=${{ env.LLVM_INSTALL_BINDIR }}/clang++"
+          )
           python3 ./tools/scripts/utils/build-and-run-unit-tests.py
           ${{matrix.use_shared_libs == 'true' && '--use-shared-libs' || ''}}
           --source-dir .
           --build-dir build
           --num-jobs $(getconf _NPROCESSORS_ONLN)
           --test-spec "~[Stopwatch]"
+          $(
+          [[ "${{ env.USE_LLVM_COMPILER }}" == "true" ]]
+          && echo
+          "--ar ${{ env.LLVM_INSTALL_BINDIR }}/llvm-ar"
+          "--ranlib ${{ env.LLVM_INSTALL_BINDIR }}/llvm-ranlib"
+          )

components/core/tools/scripts/utils/build-and-run-unit-tests.py

@@ -21,7 +21,13 @@
 logger = logging.getLogger(__name__)
 
 
-def _config_cmake_project(src_dir: Path, build_dir: Path, use_shared_libs: bool):
+def _config_cmake_project(
+    src_dir: Path,
+    build_dir: Path,
+    use_shared_libs: bool,
+    ar: Optional[Path],
+    ranlib: Optional[Path],
+):
     cmd = [
         "cmake",
         "-S",
@@ -31,6 +37,10 @@ def _config_cmake_project(src_dir: Path, build_dir: Path, use_shared_libs: bool)
     ]
     if use_shared_libs:
         cmd.append("-DCLP_USE_STATIC_LIBS=OFF")
+    if ar:
+        cmd.append(f"-DCMAKE_AR={ar}")
+    if ranlib:
+        cmd.append(f"-DCMAKE_RANLIB={ranlib}")
     subprocess.run(cmd, check=True)
 
 
@@ -82,15 +92,19 @@ def main(argv: List[str]) -> int:
         "--num-jobs", type=int, help="Max number of jobs to run when building."
     )
     args_parser.add_argument("--test-spec", help="Catch2 test specification.")
+    args_parser.add_argument("--ar", help="Archiver tool to use.")
+    args_parser.add_argument("--ranlib", help="Ranlib indexing tool to use.")
 
     parsed_args = args_parser.parse_args(argv[1:])
     src_dir: Path = Path(parsed_args.source_dir)
     build_dir: Path = Path(parsed_args.build_dir)
     use_shared_libs: bool = parsed_args.use_shared_libs
     num_jobs: Optional[int] = parsed_args.num_jobs
     test_spec: Optional[str] = parsed_args.test_spec
+    ar: Optional[Path] = parsed_args.ar
+    ranlib: Optional[Path] = parsed_args.ranlib
 
-    _config_cmake_project(src_dir, build_dir, use_shared_libs)
+    _config_cmake_project(src_dir, build_dir, use_shared_libs, ar, ranlib)
     _build_project(build_dir, num_jobs)
     _run_unit_tests(build_dir, test_spec)