workflows: build wheels for Linux and macOS

The convert module doesn't use any libc APIs, so we can build on any Linux
distro and auditwheel will tag the wheel as the oldest manylinux.

auditwheel requires setuptools on Python 3.12 for distutils.

Fixes: openslide#126
Fixes: openslide#187
Signed-off-by: Benjamin Gilbert <bgilbert@cs.cmu.edu>

.github/workflows/python.yml

@@ -31,17 +31,45 @@ jobs:
       matrix:
         os: [ubuntu-latest, macos-latest]
         python-version: [3.8, 3.9, "3.10", "3.11", "3.12"]
+        # Python 3.8 is too old to support universal binaries, and
+        # setup-python's Python 3.9 and 3.10 won't build them.  Use the
+        # last upstream patch releases that ship with installers.
+        # https://github.com/actions/setup-python/issues/439#issuecomment-1247646682
+        include:
+          - os: macos-latest
+            python-version: "3.9"
+            upstream-python: 3.9.13
+          - os: macos-latest
+            python-version: "3.10"
+            upstream-python: 3.10.11
     steps:
     - name: Check out repo
       uses: actions/checkout@v4
     - name: Set up Python ${{ matrix.python-version }}
+      if: matrix.upstream-python == null
       uses: actions/setup-python@v4
       with:
         python-version: ${{ matrix.python-version }}
+    - name: Set up Python ${{ matrix.python-version }} (macOS fallback)
+      if: matrix.upstream-python != null
+      run: |
+        pkgdir="${{ runner.temp }}/python"
+        mkdir -p "$pkgdir/bin"
+        pkg="$pkgdir/python.pkg"
+        curl -Lfo "$pkg" \
+            "https://www.python.org/ftp/python/${{ matrix.upstream-python }}/python-${{ matrix.upstream-python }}-macos11.pkg"
+        sudo installer -pkg "$pkg" -target /
+        for bin in python pip; do
+            ln -s /usr/local/bin/${bin}3 $pkgdir/bin/${bin}
+        done
+        export PATH="$pkgdir/bin:$PATH"
+        echo "PATH=$PATH" >> $GITHUB_ENV
+        python -V
+        pip -V
     - name: Install Python tools
       run: |
         python -m pip install --upgrade pip
-        pip install build jinja2 pytest
+        pip install auditwheel build jinja2 pytest setuptools
     - name: Install OpenSlide
       run: |
         case "${{ matrix.os }}" in
@@ -53,13 +81,36 @@ jobs:
           ;;
         esac
     - name: Build wheel
-      run: python -m build -w
+      run: |
+        python -m build -w
+        case "${{ matrix.os }}" in
+        ubuntu-*)
+            mkdir old
+            mv dist/*.whl old/
+            auditwheel repair --only-plat -w dist old/*whl
+            ;;
+        macos-*)
+            if [ "${{ matrix.python-version }}" != 3.8 -a ! -e dist/*universal2* ]; then
+                echo "Wheel is not universal:"
+                ls dist
+                exit 1
+            fi
+        esac
+        basename=openslide-python-wheels-$GITHUB_RUN_NUMBER-$(echo $GITHUB_SHA | cut -c-10)
+        mkdir -p "artifacts/${basename}"
+        mv dist/* "artifacts/${basename}"
+        echo "basename=${basename}" >> $GITHUB_ENV
     - name: Install
-      run: pip install dist/*.whl
+      run: pip install artifacts/${basename}/*.whl
     - name: Run tests
       run: pytest -v
     - name: Tile slide
       run: python examples/deepzoom/deepzoom_tile.py --viewer -o tiled tests/fixtures/small.svs
+    - name: Archive wheel
+      uses: actions/upload-artifact@v3
+      with:
+        name: ${{ env.basename }}
+        path: artifacts
   windows:
     name: Windows
     needs: pre-commit