WHL: build limited-api compliant wheels

Author: neutrinoceros

.github/workflows/cibuildwheel.yml

@@ -59,10 +59,8 @@ jobs:
             arch: aarch64
           - os: macos-14
             arch: arm64
-            CIBW_ENVIRONMENT: MACOSX_DEPLOYMENT_TARGET=14.0
           - os: macos-13
             arch: x86_64
-            CIBW_ENVIRONMENT: MACOSX_DEPLOYMENT_TARGET=13.0
 
     steps:
     - uses: actions/checkout@v5
@@ -80,33 +78,17 @@ jobs:
       shell: bash
       # On PRs we run only oldest and newest Python versions to reduce CI load.
       # Skips pypy and musllinux everywhere.
-      # We are buiding 38 and 312 for now.
+      # We are buiding 39 and 314 for now.
       # These needs to rotate every new Python release.
       run: |
-        if [[ "${{ github.event_name }}" == "pull_request" ]]; then
-          CIBW_SKIP="pp* cp36-* cp37-* cp38-* cp314t-* *-musllinux* cp39-* cp310-* cp311-* cp312-* cp313-*"
-        else
-          CIBW_SKIP="pp* cp36-* cp37-* cp38-* cp314t-* *-musllinux*"
-        fi
-        echo "CIBW_SKIP=$CIBW_SKIP" >> $GITHUB_ENV
-        echo "Setting CIBW_SKIP=$CIBW_SKIP"
+        echo "Setting CIBW_BUILD='cp39-* cp314-*'"
+        echo "CIBW_BUILD='cp39-* cp314-*'" >> $GITHUB_ENV
+      if: ${{ github.event_name }}" == "pull_request"
 
     - name: "Building ${{ matrix.os }} (${{ matrix.arch }}) wheels"
       uses: pypa/cibuildwheel@v3.1.4
       env:
-        CIBW_SKIP: ${{ env.CIBW_SKIP }}
         CIBW_ARCHS: ${{ matrix.arch }}
-        CIBW_BUILD_FRONTEND: build
-        CIBW_MANYLINUX_X86_64_IMAGE: ghcr.io/ocefpaf/manylinux_2_28_x86_64-netcdf
-        CIBW_MANYLINUX_AARCH64_IMAGE: ghcr.io/ocefpaf/manylinux_2_28_aarch64-netcdf
-        # Emulation testing is slow, testing only latest Python.
-        CIBW_TEST_SKIP: "cp39-*_aarch64 cp310-*_aarch64 cp311-*_aarch64 cp312-*_aarch64"
-        CIBW_ENVIRONMENT: ${{ matrix.CIBW_ENVIRONMENT }}
-        CIBW_BEFORE_BUILD_MACOS: brew install hdf5 netcdf
-        CIBW_TEST_REQUIRES: pytest cython packaging typing-extensions
-        CIBW_TEST_COMMAND: >
-          python -c "import netCDF4; print(f'netCDF4 v{netCDF4.__version__}')"
-          && pytest -s -rxs -v {project}/test
 
     - uses: actions/upload-artifact@v4
       with:

pyproject.toml

@@ -45,6 +45,7 @@ tests = [
   "Cython",
   "packaging",
   "pytest",
+  "typing-extensions",
 ]
 parallel = [
   "mpi4py",
@@ -102,3 +103,30 @@ module = [
   "filter_availability",
   "matplotlib.*"
 ]
+
+[tool.cibuildwheel]
+build-verbosity = 1
+build-frontend = "build"
+skip = [
+  "*-musllinux*",
+  "cp314t-*",
+]
+test-extras = "tests"
+test-command = [
+    """python -c "import netCDF4; print(f'netCDF4 v{netCDF4.__version__}')""",
+    "pytest -s -rxs -v {project}/test",
+]
+manylinux-x86_64-image = "ghcr.io/ocefpaf/manylinux_2_28_x86_64-netcdf"
+manylinux-aarch64-image = "ghcr.io/ocefpaf/manylinux_2_28_aarch64-netcdf"
+environment = {"NETCDF4_LIMITED_API" = "1"}
+
+[tool.cibuildwheel.macos]
+before-build = "brew install hdf5 netcdf"
+
+[[tool.cibuildwheel.macos.environment]]
+select = "x86_64"
+MACOSX_DEPLOYMENT_TARGET = "13.0"
+
+[[tool.cibuildwheel.macos.environment]]
+select = "amr64"
+MACOSX_DEPLOYMENT_TARGET = "14.0"

setup.py

@@ -3,11 +3,27 @@
 import pathlib
 import shutil
 import configparser
+import sysconfig
 from setuptools import setup, Extension
 from setuptools.dist import Distribution
 from typing import List
 
 
+USE_PY_LIMITED_API = (
+    # require opt-in (builds are specilized by default)
+    os.getenv('NETCDF4_LIMITED_API', '0') == '1'
+    # Cython + numpy + limited API de facto requires Python >=3.11
+    and sys.version_info >= (3, 11)
+    # as of Python 3.14t, free-threaded builds don't support the limited API
+    and not sysconfig.get_config_var("Py_GIL_DISABLED")
+)
+ABI3_TARGET_VERSION = "".join(str(_) for _ in sys.version_info[:2])
+ABI3_TARGET_HEX = hex(sys.hexversion & 0xFFFF00F0)
+
+if USE_PY_LIMITED_API:
+    SETUP_OPTIONS = {"bdist_wheel": {"py_limited_api": f"cp{ABI3_TARGET_VERSION}"}}
+else:
+    SETUP_OPTIONS = {}
 
 open_kwargs = {'encoding': 'utf-8'}
 
@@ -436,6 +452,8 @@ def _populate_hdf5_info(dirstosearch, inc_dirs, libs, lib_dirs):
         str(nc_complex_dir / "include/generated_fallbacks"),
     ]
     DEFINE_MACROS += [("NC_COMPLEX_NO_EXPORT", "1")]
+    if USE_PY_LIMITED_API:
+        DEFINE_MACROS.append(("Py_LIMITED_API", ABI3_TARGET_HEX))
 
     ext_modules = [Extension("netCDF4._netCDF4",
                              source_files,
@@ -477,6 +495,7 @@ def _populate_hdf5_info(dirstosearch, inc_dirs, libs, lib_dirs):
     name="netCDF4",  # need by GitHub dependency graph
     version=extract_version(netcdf4_src_pyx),
     ext_modules=ext_modules,
+    options=SETUP_OPTIONS,
 )
 
 # remove plugin files copied from outside source tree