gh-111062: Build both default and free-threaded on macOS (gh-111449)

.github/workflows/build.yml

@@ -237,6 +237,15 @@ jobs:
     with:
       config_hash: ${{ needs.check_source.outputs.config_hash }}
 
+  build_macos_free_threaded:
+    name: 'macOS (free-threaded)'
+    needs: check_source
+    if: needs.check_source.outputs.run_tests == 'true' && contains(github.event.pull_request.labels.*.name, 'topic-free-threaded')
+    uses: ./.github/workflows/reusable-build-macos.yml
+    with:
+      config_hash: ${{ needs.check_source.outputs.config_hash }}
+      free-threaded: true
+
   build_ubuntu:
     name: 'Ubuntu'
     runs-on: ubuntu-20.04

.github/workflows/reusable-build-macos.yml

@@ -4,6 +4,10 @@ on:
       config_hash:
         required: true
         type: string
+      free-threaded:
+        required: false
+        type: boolean
+        default: false
 
 jobs:
   build_macos:
@@ -30,6 +34,7 @@ jobs:
         ./configure \
           --config-cache \
           --with-pydebug \
+          ${{ inputs.free-threaded && '--disable-gil' || '' }} \
           --prefix=/opt/python-dev \
           --with-openssl="$(brew --prefix openssl@3.0)"
     - name: Build CPython