Split macos architectures (#87)

Author: alugowski

.github/workflows/wheels.yml

@@ -60,13 +60,19 @@ jobs:
             manylinux_image: manylinux2014
             cibw_archs: "aarch64"
 
-          # Use x86 macOS runner to build both x86 and ARM.
+          # macOS x86
+          - os: macos-latest
+            python-version: "3.8"
+            platform_id: macosx_x86_64
+            cibw_archs: "x86_64"
+
+          # Use x86 macOS runner to build ARM.
           # GitHub does not offer Apple Silicon yet (only for self-hosted).
           # See https://github.com/github/roadmap/issues/528
           - os: macos-latest
             python-version: "3.8"
             platform_id: macosx_x86_64
-            cibw_archs: "x86_64 arm64"
+            cibw_archs: "arm64"
 
     steps:
       - uses: actions/checkout@v3
@@ -117,7 +123,8 @@ jobs:
           CIBW_ENVIRONMENT_WINDOWS: CMAKE_GNUtoMS=ON GRAPHBLAS_PREFIX="C:/GraphBLAS"
 
           # macOS libomp requires special configs. BREW_LIBOMP=1 asks suitesparse.sh to include them.
-          CIBW_ENVIRONMENT_MACOS: BREW_LIBOMP="1"
+          # SUITESPARSE_MACOS_ARCH asks to build a particular architecture. Either x86 or arm64.
+          CIBW_ENVIRONMENT_MACOS: BREW_LIBOMP="1" SUITESPARSE_MACOS_ARCH=${{ matrix.cibw_archs }}
 
           # Uncomment to only build CPython wheels
 #          CIBW_BUILD: "cp*"
@@ -143,8 +150,8 @@ jobs:
           # run tests
           CIBW_TEST_COMMAND: "pytest --pyargs suitesparse_graphblas"
 
-          # GitHub Actions macOS Intel runner cannot run ARM tests.
-          CIBW_TEST_SKIP: "*-macosx_arm64"
+          # GitHub Actions macOS Intel runner cannot run ARM tests. Uncomment to silence warning.
+#          CIBW_TEST_SKIP: "*-macosx_arm64"
 
         run: |
           python -m pip install cibuildwheel

suitesparse.sh

@@ -25,8 +25,12 @@ if [ -n "${BREW_LIBOMP}" ]; then
     cmake_params+=(-DOpenMP_libomp_LIBRARY="omp")
     export LDFLAGS="-L$(brew --prefix libomp)/lib"
 
-    # build both x86 and ARM
-    export CFLAGS="-arch x86_64 -arch arm64"
+    if [ -n "${SUITESPARSE_MACOS_ARCH}" ]; then
+        export CFLAGS="-arch ${SUITESPARSE_MACOS_ARCH}"
+    else
+        # build both x86 and ARM
+        export CFLAGS="-arch x86_64 -arch arm64"
+    fi
 fi
 
 if [ -n "${CMAKE_GNUtoMS}" ]; then