Make use of CPython limited API

.github/workflows/ci_workflows.yml

@@ -113,7 +113,7 @@ jobs:
         python -m venv --system-site-packages tests
         source tests/bin/activate
         python -m pip install --editable .[test]
-        (nm -u erfa/ufunc.cpython-*.so | grep eraA2af) || exit 1
+        (nm -u erfa/ufunc.*.so | grep eraA2af) || exit 1
         (python -c 'import erfa' 2>&1 | grep -n 'too old') > /dev/null && (echo 'liberfa too old, skipping tests'; exit 0) || python -m pytest
 
 
@@ -126,37 +126,16 @@ jobs:
       test_command: pytest --pyargs erfa
       targets: |
         # Linux wheels
-        - cp39-manylinux_x86_64
-        - cp310-manylinux_x86_64
-        - cp311-manylinux_x86_64
-        - cp312-manylinux_x86_64
-        - cp39-musllinux_x86_64
-        - cp310-musllinux_x86_64
-        - cp311-musllinux_x86_64
-        - cp312-musllinux_x86_64
-        - cp39-manylinux_aarch64
-        - cp310-manylinux_aarch64
-        - cp311-manylinux_aarch64
-        - cp312-manylinux_aarch64
+        - cp3*-manylinux_x86_64
+        - cp3*-musllinux_x86_64
+        - cp3*-manylinux_aarch64
         # MacOS X wheels - we deliberately do not build universal2 wheels.
         # Note that the arm64 wheels are not actually tested so we
         # rely on local manual testing of these to make sure they are ok.
-        - cp39*macosx_x86_64
-        - cp310*macosx_x86_64
-        - cp311*macosx_x86_64
-        - cp312*macosx_x86_64
-        - cp39*macosx_arm64
-        - cp310*macosx_arm64
-        - cp311*macosx_arm64
-        - cp312*macosx_arm64
+        - cp3*macosx_x86_64
+        - cp3*macosx_arm64
         # Windows wheels
-        - cp39*win32
-        - cp310*win32
-        - cp311*win32
-        - cp312*win32
-        - cp39*win_amd64
-        - cp310*win_amd64
-        - cp311*win_amd64
-        - cp312*win_amd64
+        - cp3*win32
+        - cp3*win_amd64
     secrets:
       pypi_token: ${{ secrets.pypi_token }}

erfa/ufunc.c.templ

@@ -10,12 +10,24 @@
  */
 
 #define NPY_NO_DEPRECATED_API NPY_1_7_API_VERSION
+#define Py_LIMITED_API 0x030900f0
 #include "Python.h"
 #include "numpy/arrayobject.h"
 #include "numpy/ufuncobject.h"
 #include "erfa.h"
 #include "erfaextra.h"
 
+// On gcc<10 we can run into the following:
+//
+//   error: dereferencing pointer to incomplete type 'PyTypeObject'
+//
+// As mentioned in https://github.com/numpy/numpy/issues/16970,
+// the workaround is to define a fake _typeobject struct.
+
+struct _typeobject {
+    int dummy;
+};
+
 #define MODULE_DOCSTRING \
     "Ufunc wrappers of the ERFA routines.\n\n" \
     "These ufuncs vectorize the ERFA functions assuming structured dtypes\n" \
@@ -207,7 +219,9 @@ static void ufunc_loop_{{ func.pyname }}(
    {#- /* if needed, allocate memory for contiguous eraLDBODY copies */ #}
    {%- if func.user_dtype == 'dt_eraLDBODY' %}
     if (copy_b) {
-        _b = PyArray_malloc(nb * sizeof(eraLDBODY));
+        // Note that we can't use PyArray_malloc here as it is an alias to PyMem_RawMalloc
+        // which is not available in the Python limited API
+        _b = malloc(nb * sizeof(eraLDBODY));
         if (_b == NULL) {
             PyErr_NoMemory();
             return;

setup.cfg

@@ -56,3 +56,6 @@ max-line-length = 100
 
 [pycodestyle]
 max-line-length = 100
+
+[bdist_wheel]
+py_limited_api = cp39

setup.py

@@ -147,6 +147,7 @@ def get_extensions():
         include_dirs=include_dirs,
         libraries=libraries,
         define_macros=define_macros,
+        py_limited_api=True,
         language="c")
 
     return [erfa_ext]