Generate CI matrix at runtime (#428)

Generates the CI matrix dynamically so we can run subsets on pull
requests.

- Moves the matrix definition out of GitHub workflows into a
`ci-targets.yaml` file
- Adds a `ci-matrix.py` script which parses the `ci-targets.yaml` file
and outputs a JSON matrix
- Updates the GitHub Actions workflows to use the script to generate a
matrix dynamically
- Uses the labels on the pull request to allow subsetting of the matrix

For example, you can run the matrix generator locally to see the label
subsetting in action:

```console
❯ uv run ci-matrix.py --label arch:x86_64,platform:linux,libc:gnu,build:freethreaded,build:lto | jq
Reading inline script metadata from `ci-matrix.py`
{
  "include": [
    {
      "arch": "x86_64",
      "target_triple": "x86_64-unknown-linux-gnu",
      "platform": "linux",
      "libc": "gnu",
      "run": "true",
      "python": "3.13",
      "build_options": "freethreaded+pgo+lto"
    },
    {
      "arch": "x86_64",
      "target_triple": "x86_64_v2-unknown-linux-gnu",
      "platform": "linux",
      "arch_variant": "v2",
      "libc": "gnu",
      "run": "true",
      "python": "3.13",
      "build_options": "freethreaded+pgo+lto"
    },
    {
      "arch": "x86_64",
      "target_triple": "x86_64_v3-unknown-linux-gnu",
      "platform": "linux",
      "arch_variant": "v3",
      "libc": "gnu",
      "run": "true",
      "python": "3.13",
      "build_options": "freethreaded+pgo+lto"
    },
    {
      "arch": "x86_64",
      "target_triple": "x86_64_v4-unknown-linux-gnu",
      "platform": "linux",
      "arch_variant": "v4",
      "libc": "gnu",
      "python": "3.13",
      "build_options": "freethreaded+lto"
    }
  ]
}
```

I'll add labels for

- `platform:darwin`
- `platform:linux`
- `platform:windows`
- `python:3.9`
- `python:3.10`
- `python:3.11`
- `python:3.12`
- `python:3.13`
- `build:debug`
- `build:pgo`
- `build:lto`
- `build:noopt`
- `build:freethreaded`
- `arch:x86_64`
- `arch:aarch64`
- `arch:armv7`
- `arch:s390x`
- `arch:ppc64le`
- `arch:x86`
- `libc:gnu`
- `libc:musl`

In a follow-up, I'll update this to use different runners in forks as
noted in #426

Author: zanieb

.github/workflows/apple.yml

@@ -40,135 +40,39 @@ jobs:
           name: pythonbuild
           path: target/release/pythonbuild
 
+  generate-matrix:
+    runs-on: ubuntu-latest
+    outputs:
+      matrix: ${{ steps.set-matrix.outputs.matrix }}
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: astral-sh/setup-uv@v4
+
+      - name: Get pull request labels
+        id: get-labels
+        run: |
+          # Convert GitHub labels array to comma-separated string
+          LABELS=$(echo '${{ toJson(github.event.pull_request.labels.*.name) }}' | jq -r 'join(",")')
+          echo "labels=$LABELS" >> $GITHUB_OUTPUT
+
+      - name: Generate build matrix
+        id: set-matrix
+        run: |
+          uv run ci-matrix.py --platform darwin --labels "${{ steps.get-labels.outputs.labels }}" > matrix.json && echo "matrix=$(cat matrix.json)" >> $GITHUB_OUTPUT
+          # Display the matrix for debugging too
+          cat matrix.json | jq
+
   build:
-    strategy:
-      fail-fast: false
-      matrix:
-        build:
-          - target_triple: 'aarch64-apple-darwin'
-            py: 'cpython-3.9'
-            options: 'debug'
-          - target_triple: 'aarch64-apple-darwin'
-            py: 'cpython-3.9'
-            options: 'pgo'
-          - target_triple: 'aarch64-apple-darwin'
-            py: 'cpython-3.9'
-            options: 'pgo+lto'
-
-          - target_triple: 'aarch64-apple-darwin'
-            py: 'cpython-3.10'
-            options: 'debug'
-          - target_triple: 'aarch64-apple-darwin'
-            py: 'cpython-3.10'
-            options: 'pgo'
-          - target_triple: 'aarch64-apple-darwin'
-            py: 'cpython-3.10'
-            options: 'pgo+lto'
-
-          - target_triple: 'aarch64-apple-darwin'
-            py: 'cpython-3.11'
-            options: 'debug'
-          - target_triple: 'aarch64-apple-darwin'
-            py: 'cpython-3.11'
-            options: 'pgo'
-          - target_triple: 'aarch64-apple-darwin'
-            py: 'cpython-3.11'
-            options: 'pgo+lto'
-
-          - target_triple: 'aarch64-apple-darwin'
-            py: 'cpython-3.12'
-            options: 'debug'
-          - target_triple: 'aarch64-apple-darwin'
-            py: 'cpython-3.12'
-            options: 'pgo'
-          - target_triple: 'aarch64-apple-darwin'
-            py: 'cpython-3.12'
-            options: 'pgo+lto'
-
-          - target_triple: 'aarch64-apple-darwin'
-            py: 'cpython-3.13'
-            options: 'debug'
-          - target_triple: 'aarch64-apple-darwin'
-            py: 'cpython-3.13'
-            options: 'pgo'
-          - target_triple: 'aarch64-apple-darwin'
-            py: 'cpython-3.13'
-            options: 'pgo+lto'
-
-          - target_triple: 'aarch64-apple-darwin'
-            py: 'cpython-3.13'
-            options: 'freethreaded+debug'
-          - target_triple: 'aarch64-apple-darwin'
-            py: 'cpython-3.13'
-            options: 'freethreaded+pgo'
-          - target_triple: 'aarch64-apple-darwin'
-            py: 'cpython-3.13'
-            options: 'freethreaded+pgo+lto'
-
-          # macOS on Intel hardware. This is pretty straightforward. We exclude
-          # noopt because it doesn't provide any compelling advantages over PGO
-          # or LTO builds.
-          - target_triple: 'x86_64-apple-darwin'
-            py: 'cpython-3.9'
-            options: 'debug'
-          - target_triple: 'x86_64-apple-darwin'
-            py: 'cpython-3.9'
-            options: 'pgo'
-          - target_triple: 'x86_64-apple-darwin'
-            py: 'cpython-3.9'
-            options: 'pgo+lto'
-
-          - target_triple: 'x86_64-apple-darwin'
-            py: 'cpython-3.10'
-            options: 'debug'
-          - target_triple: 'x86_64-apple-darwin'
-            py: 'cpython-3.10'
-            options: 'pgo'
-          - target_triple: 'x86_64-apple-darwin'
-            py: 'cpython-3.10'
-            options: 'pgo+lto'
-
-          - target_triple: 'x86_64-apple-darwin'
-            py: 'cpython-3.11'
-            options: 'debug'
-          - target_triple: 'x86_64-apple-darwin'
-            py: 'cpython-3.11'
-            options: 'pgo'
-          - target_triple: 'x86_64-apple-darwin'
-            py: 'cpython-3.11'
-            options: 'pgo+lto'
-
-          - target_triple: 'x86_64-apple-darwin'
-            py: 'cpython-3.12'
-            options: 'debug'
-          - target_triple: 'x86_64-apple-darwin'
-            py: 'cpython-3.12'
-            options: 'pgo'
-          - target_triple: 'x86_64-apple-darwin'
-            py: 'cpython-3.12'
-            options: 'pgo+lto'
-
-          - target_triple: 'x86_64-apple-darwin'
-            py: 'cpython-3.13'
-            options: 'debug'
-          - target_triple: 'x86_64-apple-darwin'
-            py: 'cpython-3.13'
-            options: 'pgo'
-          - target_triple: 'x86_64-apple-darwin'
-            py: 'cpython-3.13'
-            options: 'pgo+lto'
-          - target_triple: 'x86_64-apple-darwin'
-            py: 'cpython-3.13'
-            options: 'freethreaded+debug'
-          - target_triple: 'x86_64-apple-darwin'
-            py: 'cpython-3.13'
-            options: 'freethreaded+pgo'
-          - target_triple: 'x86_64-apple-darwin'
-            py: 'cpython-3.13'
-            options: 'freethreaded+pgo+lto'
     needs:
+      - generate-matrix
       - pythonbuild
-    runs-on: depot-macos-14
+    strategy:
+      matrix: ${{ fromJson(needs.generate-matrix.outputs.matrix) }}
+      fail-fast: false
+    runs-on: macos-14
+    name: ${{ matrix.target_triple }} / ${{ matrix.python }} / ${{ matrix.build_options }}
     steps:
       - uses: actions/checkout@v4
         with:
@@ -187,21 +91,21 @@ jobs:
 
       - name: Build
         run: |
-          if [ "${{ matrix.build.target_triple }}" = "aarch64-apple-darwin" ]; then
+          if [ "${{ matrix.target_triple }}" = "aarch64-apple-darwin" ]; then
             export APPLE_SDK_PATH=/Applications/Xcode_15.2.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk
-          elif [ "${{ matrix.build.target_triple }}" = "x86_64-apple-darwin" ]; then
+          elif [ "${{ matrix.target_triple }}" = "x86_64-apple-darwin" ]; then
             export APPLE_SDK_PATH=/Applications/Xcode_15.2.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk
           else
-            echo "unhandled target triple: ${{ matrix.build.target_triple }}"
+            echo "unhandled target triple: ${{ matrix.target_triple }}"
             exit 1
           fi
 
-          ./build-macos.py --target-triple ${{ matrix.build.target_triple }} --python ${{ matrix.build.py }} --options ${{ matrix.build.options }}
+          ./build-macos.py --target-triple ${{ matrix.target_triple }} --python cpython-${{ matrix.python }} --options ${{ matrix.build_options }}
 
       - name: Upload Distributions
         uses: actions/upload-artifact@v4
         with:
-          name: ${{ matrix.build.py }}-${{ matrix.build.target_triple }}-${{ matrix.build.options }}
+          name: cpython-${{ matrix.python }}-${{ matrix.target_triple }}-${{ matrix.build_options }}
           path: dist/*
 
       - uses: actions/checkout@v4