gh-117142: Port _ctypes to multi-phase init

Lib/test/test_ctypes/test_refcounts.py

@@ -4,6 +4,7 @@
 import unittest
 from test import support
 from test.support import import_helper
+from test.support import script_helper
 _ctypes_test = import_helper.import_module("_ctypes_test")
 
 
@@ -110,5 +111,18 @@ def func():
                     func()
 
 
+class ModuleIsolationTest(unittest.TestCase):
+    def test_finalize(self):
+        # check if gc_decref() succeeds
+        script = (
+            "import ctypes;"
+            "import sys;"
+            "del sys.modules['_ctypes'];"
+            "import _ctypes;"
+            "exit()"
+        )
+        script_helper.assert_python_ok("-c", script)
+
+
 if __name__ == '__main__':
     unittest.main()

Misc/NEWS.d/next/Library/2024-03-29-12-21-40.gh-issue-117142.U0agfh.rst

@@ -0,0 +1 @@
+Convert :mod:`!_ctypes` to multi-phase initialisation (:pep:`489`).