[3.13] gh-120782: Update internal type cache when reloading datetime (GH-120829)

Lib/test/datetimetester.py

@@ -52,25 +52,6 @@
     pass
 #
 
-# This is copied from test_import/__init__.py.
-def no_rerun(reason):
-    """Skip rerunning for a particular test.
-
-    WARNING: Use this decorator with care; skipping rerunning makes it
-    impossible to find reference leaks. Provide a clear reason for skipping the
-    test using the 'reason' parameter.
-    """
-    def deco(func):
-        _has_run = False
-        def wrapper(self):
-            nonlocal _has_run
-            if _has_run:
-                self.skipTest(reason)
-            func(self)
-            _has_run = True
-        return wrapper
-    return deco
-
 pickle_loads = {pickle.loads, pickle._loads}
 
 pickle_choices = [(pickle, pickle, proto)
@@ -6412,7 +6393,6 @@ class IranTest(ZoneInfoTest):
 
 
 @unittest.skipIf(_testcapi is None, 'need _testcapi module')
-@no_rerun("the encapsulated datetime C API does not support reloading")
 class CapiTest(unittest.TestCase):
     def setUp(self):
         # Since the C API is not present in the _Pure tests, skip all tests
@@ -6881,6 +6861,38 @@ def pickle_fake_date(datetime_) -> Type[FakeDate]:
                 """)
             script_helper.assert_python_ok('-c', script)
 
+    def test_update_type_cache(self):
+        # gh-120782
+        script = textwrap.dedent("""
+            import sys
+            for i in range(5):
+                import _datetime
+                assert _datetime.date.max > _datetime.date.min
+                assert _datetime.time.max > _datetime.time.min
+                assert _datetime.datetime.max > _datetime.datetime.min
+                assert _datetime.timedelta.max > _datetime.timedelta.min
+                assert _datetime.date.__dict__["min"] is _datetime.date.min
+                assert _datetime.date.__dict__["max"] is _datetime.date.max
+                assert _datetime.date.__dict__["resolution"] is _datetime.date.resolution
+                assert _datetime.time.__dict__["min"] is _datetime.time.min
+                assert _datetime.time.__dict__["max"] is _datetime.time.max
+                assert _datetime.time.__dict__["resolution"] is _datetime.time.resolution
+                assert _datetime.datetime.__dict__["min"] is _datetime.datetime.min
+                assert _datetime.datetime.__dict__["max"] is _datetime.datetime.max
+                assert _datetime.datetime.__dict__["resolution"] is _datetime.datetime.resolution
+                assert _datetime.timedelta.__dict__["min"] is _datetime.timedelta.min
+                assert _datetime.timedelta.__dict__["max"] is _datetime.timedelta.max
+                assert _datetime.timedelta.__dict__["resolution"] is _datetime.timedelta.resolution
+                assert _datetime.timezone.__dict__["min"] is _datetime.timezone.min
+                assert _datetime.timezone.__dict__["max"] is _datetime.timezone.max
+                assert _datetime.timezone.__dict__["utc"] is _datetime.timezone.utc
+                assert isinstance(_datetime.timezone.min, _datetime.tzinfo)
+                assert isinstance(_datetime.timezone.max, _datetime.tzinfo)
+                assert isinstance(_datetime.timezone.utc, _datetime.tzinfo)
+                del sys.modules['_datetime']
+            """)
+        script_helper.assert_python_ok('-c', script)
+
 
 def load_tests(loader, standard_tests, pattern):
     standard_tests.addTest(ZoneInfoCompleteTest())

Misc/NEWS.d/next/Library/2024-06-21-12-00-16.gh-issue-120782.LOE8tj.rst

@@ -0,0 +1 @@
+Fix wrong references of the :mod:`datetime` types after reloading the module.

Modules/_datetimemodule.c

@@ -7293,6 +7293,12 @@ _datetime_exec(PyObject *module)
     static_assert(DI100Y == 25 * DI4Y - 1, "DI100Y");
     assert(DI100Y == days_before_year(100+1));
 
+    if (reloading) {
+        for (size_t i = 0; i < Py_ARRAY_LENGTH(capi_types); i++) {
+            PyType_Modified(capi_types[i]);
+        }
+    }
+
     if (set_current_module(interp, module) < 0) {
         goto error;
     }