[SCSB-237] build Stable ABI3 wheels with Py_LIMITED_API

.github/workflows/build.yml

@@ -0,0 +1,71 @@
+name: build
+
+on:
+  pull_request:
+  release:
+    types: [released]
+  workflow_dispatch:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+permissions: {}
+
+jobs:
+  build:
+    strategy:
+      matrix:
+        runs-on:
+          - ubuntu-latest
+          - macos-latest
+    runs-on: ${{ matrix.runs-on }}
+    steps:
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
+        with:
+          fetch-tags: true
+          fetch-depth: 0
+          persist-credentials: false
+      - uses: actions/setup-python@ece7cb06caefa5fff74198d8649806c4678c61a1 # v6.3.0
+        with:
+          python-version: "3"
+          pip-install: build
+      - if: ${{ runner.os == 'Linux' }}
+        uses: docker/setup-qemu-action@96fe6ef7f33517b61c61be40b68a1882f3264fb8 # v4.2.0
+        with:
+          platforms: all
+      - uses: pypa/cibuildwheel@294735312765b09d24a2fbec22660ce817587d55 # v4.1.0
+        with:
+          package-dir: ./
+          output-dir: dist/
+      - run: python -m build --sdist
+      - uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
+        with:
+          name: dist-${{ runner.os }}-${{ runner.arch }}
+          path: ./dist/
+  publish:
+    if: (github.event_name == 'release') && (github.event.action == 'released')
+    needs: [build]
+    runs-on: ubuntu-latest
+    permissions:
+      id-token: write
+      attestations: write
+    # To add required reviewers before deployment,
+    # edit the protection rules in GitHub Settings:
+    # Settings > Environments > pypi > Add required reviewers
+    environment:
+      name: pypi
+      url: https://pypi.org/p/reftools
+    steps:
+      - uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
+        with:
+          pattern: dist*
+          path: dist/
+          merge-multiple: true
+      - uses: actions/attest@a1948c3f048ba23858d222213b7c278aabede763 # v4.1.1
+        with:
+          subject-path: "dist/*"
+      # To upload to PyPI without a token, add this workflow file as a Trusted Publisher in the project settings on the PyPI website
+      - uses: pypa/gh-action-pypi-publish@cef221092ed1bacb1cc03d23a2d87d1d172e277b # v1.14.0
+        with:
+          password: ${{ secrets.PYPI_PASSWORD_STSCI_MAINTAINER }}

pyproject.toml

@@ -2,3 +2,10 @@
 requires = ["setuptools>=82.0.1",
             "setuptools_scm"]
 build-backend = "setuptools.build_meta"
+
+[tool.cibuildwheel]
+build = [
+    "cp39-*",  # build for CPython 3.9 Stable API
+    "cp3*t-*",  # build for free-threaded Python
+]
+test-command = "python -c 'from reftools import _computephotpars'"

setup.py

@@ -1,10 +1,28 @@
 #!/usr/bin/env python
+import sysconfig
 from glob import glob
-from setuptools import setup, Extension
+
+from setuptools import Extension, setup
+
+FREE_THREADED_PYTHON = sysconfig.get_config_var("Py_GIL_DISABLED") == 1
+
+MACROS = []
+if not FREE_THREADED_PYTHON:
+    MACROS.append(("Py_LIMITED_API", 0x03090000))  # PY_VERSION_HEX for 3.9
+
+SETUPTOOLS_OPTIONS = {}
+if not FREE_THREADED_PYTHON:
+    SETUPTOOLS_OPTIONS["bdist_wheel"] = {"py_limited_api": "cp39"}
 
 setup(
-    use_scm_version={'write_to': 'reftools/version.py'},
+    use_scm_version={"write_to": "reftools/version.py"},
     ext_modules=[
-        Extension('reftools._computephotpars', glob('reftools/src/*.c'))
-    ]
+        Extension(
+            "reftools._computephotpars",
+            glob("reftools/src/*.c"),
+            define_macros=MACROS,
+            py_limited_api=not FREE_THREADED_PYTHON,
+        )
+    ],
+    options=SETUPTOOLS_OPTIONS,
 )