Support free-threading builds of Python 3.14t

Build wheels for 3.14t, and declare that our extension module doesn't
rely on the GIL.

Signed-off-by: Matt Wozniski <mwozniski@bloomberg.net>

Author: godlygeek

.github/workflows/build_wheels.yml

@@ -68,7 +68,7 @@ jobs:
       - name: Build wheels
         uses: pypa/cibuildwheel@v3.0.1
         env:
-          CIBW_BUILD: "cp3{8..14}-${{ matrix.wheel_type }}"
+          CIBW_BUILD: "cp3{8..14}{t,}-${{ matrix.wheel_type }}"
           CIBW_ARCHS_LINUX: auto aarch64
           CIBW_ENABLE: cpython-prerelease
       - uses: actions/upload-artifact@v4

setup.py

@@ -33,6 +33,7 @@
     "cdivision": True,
     "c_string_type": "unicode",
     "c_string_encoding": "utf8",
+    "freethreading_compatible": True,
 }
 
 DEFINE_MACROS = []
@@ -50,6 +51,7 @@
         "infer_types": True,
         "c_string_type": "unicode",
         "c_string_encoding": "utf8",
+        "freethreading_compatible": True,
     }
     DEFINE_MACROS.extend([("CYTHON_TRACE", "1"), ("CYTHON_TRACE_NOGIL", "1")])
 

tests/integration/empty_thread_extension/testext.cpp

@@ -39,7 +39,11 @@ static struct PyModuleDef moduledef = {PyModuleDef_HEAD_INIT, "testext", "", -1,
 PyMODINIT_FUNC
 PyInit_testext(void)
 {
-    return PyModule_Create(&moduledef);
+    PyObject *mod = PyModule_Create(&moduledef);
+#ifdef Py_GIL_DISABLED
+    PyUnstable_Module_SetGIL(mod, Py_MOD_GIL_NOT_USED);
+#endif
+    return mod;
 }
 #else
 PyMODINIT_FUNC

tests/integration/empty_thread_extension_with_os_threads/testext.cpp

@@ -69,7 +69,11 @@ static struct PyModuleDef moduledef = {PyModuleDef_HEAD_INIT, "testext", "", -1,
 PyMODINIT_FUNC
 PyInit_testext(void)
 {
-    return PyModule_Create(&moduledef);
+    PyObject *mod = PyModule_Create(&moduledef);
+#ifdef Py_GIL_DISABLED
+    PyUnstable_Module_SetGIL(mod, Py_MOD_GIL_NOT_USED);
+#endif
+    return mod;
 }
 #else
 PyMODINIT_FUNC