From 5a5f522ce0c45dc56393dbddc89b4fef626e37be Mon Sep 17 00:00:00 2001
From: Changaco <changaco@changaco.oy.lc>
Date: Sun, 12 Apr 2026 21:12:23 +0000
Subject: [PATCH 1/7] restore historical behavior of `defaultdict`

Partial revert of GH-142668 (a0434075108efe6acdfba34f42545f4d80ac9a5e).
---
 Lib/test/test_defaultdict.py | 10 +++++++---
 Modules/_collectionsmodule.c | 10 +++++-----
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/Lib/test/test_defaultdict.py b/Lib/test/test_defaultdict.py
index a193eb10f16d17..5d3cc3bf72983c 100644
--- a/Lib/test/test_defaultdict.py
+++ b/Lib/test/test_defaultdict.py
@@ -51,7 +51,11 @@ def test_missing(self):
         d1 = defaultdict()
         self.assertRaises(KeyError, d1.__missing__, 42)
         d1.default_factory = list
-        self.assertEqual(d1.__missing__(42), [])
+        v1 = d1.__missing__(42)
+        self.assertEqual(v1, [])
+        v2 = d1.__missing__(42)
+        self.assertEqual(v2, [])
+        self.assertIsNot(v2, v1)
 
     def test_repr(self):
         d1 = defaultdict()
@@ -186,7 +190,7 @@ def test_union(self):
         with self.assertRaises(TypeError):
             i |= None
 
-    def test_factory_conflict_with_set_value(self):
+    def test_reentering_getitem_method(self):
         key = "conflict_test"
         count = 0
 
@@ -201,7 +205,7 @@ def default_factory():
         test_dict = defaultdict(default_factory)
 
         self.assertEqual(count, 0)
-        self.assertEqual(test_dict[key], 2)
+        self.assertEqual(test_dict[key], 1)
         self.assertEqual(count, 2)
 
     def test_repr_recursive_factory(self):
diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c
index 4ff05727ebc8ce..93bf4beeb0c20b 100644
--- a/Modules/_collectionsmodule.c
+++ b/Modules/_collectionsmodule.c
@@ -2247,11 +2247,11 @@ defdict_missing(PyObject *op, PyObject *key)
     value = _PyObject_CallNoArgs(factory);
     if (value == NULL)
         return value;
-    PyObject *result = NULL;
-    (void)PyDict_SetDefaultRef(op, key, value, &result);
-    // 'result' is NULL, or a strong reference to 'value' or 'op[key]'
-    Py_DECREF(value);
-    return result;
+    if (PyObject_SetItem(op, key, value) < 0) {
+        Py_DECREF(value);
+        return NULL;
+    }
+    return value;
 }
 
 static inline PyObject*

From 0985fd10099a7434359197927e03bbaae60e7cd6 Mon Sep 17 00:00:00 2001
From: Changaco <changaco@changaco.oy.lc>
Date: Sun, 12 Apr 2026 21:22:35 +0000
Subject: [PATCH 2/7] simplify the `defdict_missing` function

---
 Modules/_collectionsmodule.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c
index 93bf4beeb0c20b..90a1a586ecd6d7 100644
--- a/Modules/_collectionsmodule.c
+++ b/Modules/_collectionsmodule.c
@@ -2237,11 +2237,7 @@ defdict_missing(PyObject *op, PyObject *key)
     PyObject *value;
     if (factory == NULL || factory == Py_None) {
         /* XXX Call dict.__missing__(key) */
-        PyObject *tup;
-        tup = PyTuple_Pack(1, key);
-        if (!tup) return NULL;
-        PyErr_SetObject(PyExc_KeyError, tup);
-        Py_DECREF(tup);
+        _PyErr_SetKeyError(key);
         return NULL;
     }
     value = _PyObject_CallNoArgs(factory);

From 03d0d1104173aa7592b8580e04a424d16404484b Mon Sep 17 00:00:00 2001
From: Changaco <changaco@changaco.oy.lc>
Date: Sun, 12 Apr 2026 22:44:33 +0000
Subject: [PATCH 3/7] defaultdict: remove __missing__, add __getitem__

---
 Doc/library/collections.rst            | 47 ++++++++----------
 Include/internal/pycore_dict.h         |  2 +
 Lib/importlib/metadata/__init__.py     | 14 +++---
 Lib/importlib/metadata/_collections.py | 24 ----------
 Lib/pydoc_data/topics.py               |  3 +-
 Lib/test/test_defaultdict.py           | 18 +++----
 Modules/_collectionsmodule.c           | 66 ++++++++++++++++++--------
 Objects/dictobject.c                   | 28 +++++------
 Python/ceval.c                         |  4 +-
 9 files changed, 102 insertions(+), 104 deletions(-)

diff --git a/Doc/library/collections.rst b/Doc/library/collections.rst
index cb9300f072b9e7..6eacaf92f5fc75 100644
--- a/Doc/library/collections.rst
+++ b/Doc/library/collections.rst
@@ -740,43 +740,38 @@ stack manipulations such as ``dup``, ``drop``, ``swap``, ``over``, ``pick``,
     arguments.
 
 
-    :class:`defaultdict` objects support the following method in addition to the
-    standard :class:`dict` operations:
+    :class:`defaultdict` overrides the following method:
 
-    .. method:: __missing__(key, /)
+    .. method:: __getitem__(key, /)
 
-        If the :attr:`default_factory` attribute is ``None``, this raises a
-        :exc:`KeyError` exception with the *key* as argument.
+        Return ``self[key]``. If the item doesn't exist, it is automatically created.
+        The value is generated by calling either the :meth:`~object.__missing__` method
+        (if it exists) or the :attr:`default_factory` attribute (if it isn't None). If
+        neither can be called, a :exc:`KeyError` is raised.
 
-        If :attr:`default_factory` is not ``None``, it is called without arguments
-        to provide a default value for the given *key*, this value is inserted in
-        the dictionary for the *key*, and returned.
-
-        If calling :attr:`default_factory` raises an exception this exception is
-        propagated unchanged.
-
-        This method is called by the :meth:`~object.__getitem__` method of the
-        :class:`dict` class when the requested key is not found; whatever it
-        returns or raises is then returned or raised by :meth:`~object.__getitem__`.
-
-        Note that :meth:`__missing__` is *not* called for any operations besides
-        :meth:`~object.__getitem__`. This means that :meth:`~dict.get` will, like
-        normal dictionaries, return ``None`` as a default rather than using
-        :attr:`default_factory`.
+        When :term:`free threading` is enabled, the defaultdict is locked while the
+        key is being looked up and the default value is being generated.
 
 
     :class:`defaultdict` objects support the following instance variable:
 
-
     .. attribute:: default_factory
 
-        This attribute is used by the :meth:`~defaultdict.__missing__` method;
-        it is initialized from the first argument to the constructor, if present,
-        or to ``None``, if absent.
+        This attribute is called by the :meth:`defaultdict.__getitem__` method
+        if the requested key isn't in the dictionary. It must be either a
+        callable that takes no arguments, or :const:`None`.
+
 
     .. versionchanged:: 3.9
-       Added merge (``|``) and update (``|=``) operators, specified in
-       :pep:`584`.
+        Added merge (``|``) and update (``|=``) operators, specified in
+        :pep:`584`.
+
+    .. versionchanged:: 3.15
+        The built-in :meth:`defaultdict.__missing__` method no longer exists. A
+        custom :meth:`~object.__missing__` method should no longer insert the
+        generated value into the dictionary, as this is done by the new
+        :meth:`__getitem__` method. defaultdict is now safe to use with
+        :term:`free threading`.
 
 
 :class:`defaultdict` Examples
diff --git a/Include/internal/pycore_dict.h b/Include/internal/pycore_dict.h
index 6c6e3b77e69fab..56a29c586f67f5 100644
--- a/Include/internal/pycore_dict.h
+++ b/Include/internal/pycore_dict.h
@@ -123,6 +123,8 @@ PyAPI_FUNC(Py_ssize_t) _Py_dict_lookup(PyDictObject *mp, PyObject *key, Py_hash_
 extern Py_ssize_t _Py_dict_lookup_threadsafe(PyDictObject *mp, PyObject *key, Py_hash_t hash, PyObject **value_addr);
 extern Py_ssize_t _Py_dict_lookup_threadsafe_stackref(PyDictObject *mp, PyObject *key, Py_hash_t hash, _PyStackRef *value_addr);
 
+extern void _Py_dict_unhashable_type(PyObject *op, PyObject *key);
+
 extern int _PyDict_GetMethodStackRef(PyDictObject *dict, PyObject *name, _PyStackRef *method);
 
 // Exported for external JIT support
diff --git a/Lib/importlib/metadata/__init__.py b/Lib/importlib/metadata/__init__.py
index 32f4b7d2d6e08b..b3acfa48688c3c 100644
--- a/Lib/importlib/metadata/__init__.py
+++ b/Lib/importlib/metadata/__init__.py
@@ -22,6 +22,7 @@
 import sys
 import textwrap
 import types
+from collections import defaultdict
 from collections.abc import Iterable, Mapping
 from contextlib import suppress
 from importlib import import_module
@@ -30,7 +31,7 @@
 from typing import Any
 
 from . import _meta
-from ._collections import FreezableDefaultDict, Pair
+from ._collections import Pair
 from ._context import ExceptionTrap
 from ._functools import method_cache, noop, pass_none, passthrough
 from ._itertools import always_iterable, bucket, unique_everseen
@@ -889,8 +890,8 @@ def __init__(self, path: FastPath):
 
         base = os.path.basename(path.root).lower()
         base_is_egg = base.endswith(".egg")
-        self.infos = FreezableDefaultDict(list)
-        self.eggs = FreezableDefaultDict(list)
+        self.infos = defaultdict(list)
+        self.eggs = defaultdict(list)
 
         for child in path.children():
             low = child.lower()
@@ -904,20 +905,17 @@ def __init__(self, path: FastPath):
                 legacy_normalized = Prepared.legacy_normalize(name)
                 self.eggs[legacy_normalized].append(path.joinpath(child))
 
-        self.infos.freeze()
-        self.eggs.freeze()
-
     def search(self, prepared: Prepared):
         """
         Yield all infos and eggs matching the Prepared query.
         """
         infos = (
-            self.infos[prepared.normalized]
+            self.infos.get(prepared.normalized, ())
             if prepared
             else itertools.chain.from_iterable(self.infos.values())
         )
         eggs = (
-            self.eggs[prepared.legacy_normalized]
+            self.eggs.get(prepared.legacy_normalized, ())
             if prepared
             else itertools.chain.from_iterable(self.eggs.values())
         )
diff --git a/Lib/importlib/metadata/_collections.py b/Lib/importlib/metadata/_collections.py
index fc5045d36be572..0049814eafd37d 100644
--- a/Lib/importlib/metadata/_collections.py
+++ b/Lib/importlib/metadata/_collections.py
@@ -1,30 +1,6 @@
-import collections
 import typing
 
 
-# from jaraco.collections 3.3
-class FreezableDefaultDict(collections.defaultdict):
-    """
-    Often it is desirable to prevent the mutation of
-    a default dict after its initial construction, such
-    as to prevent mutation during iteration.
-
-    >>> dd = FreezableDefaultDict(list)
-    >>> dd[0].append('1')
-    >>> dd.freeze()
-    >>> dd[1]
-    []
-    >>> len(dd)
-    1
-    """
-
-    def __missing__(self, key):
-        return getattr(self, '_frozen', super().__missing__)(key)
-
-    def freeze(self):
-        self._frozen = lambda key: self.default_factory()
-
-
 class Pair(typing.NamedTuple):
     name: str
     value: str
diff --git a/Lib/pydoc_data/topics.py b/Lib/pydoc_data/topics.py
index 68f6771d4cedcf..599e934ed9838c 100644
--- a/Lib/pydoc_data/topics.py
+++ b/Lib/pydoc_data/topics.py
@@ -13626,8 +13626,7 @@ class dict(iterable, /, **kwargs)
          1
 
       The example above shows part of the implementation of
-      "collections.Counter". A different "__missing__()" method is
-      used by "collections.defaultdict".
+      "collections.Counter".
 
    d[key] = value
 
diff --git a/Lib/test/test_defaultdict.py b/Lib/test/test_defaultdict.py
index 5d3cc3bf72983c..4021a4d12fb644 100644
--- a/Lib/test/test_defaultdict.py
+++ b/Lib/test/test_defaultdict.py
@@ -14,6 +14,7 @@ class TestDefaultDict(unittest.TestCase):
     def test_basic(self):
         d1 = defaultdict()
         self.assertEqual(d1.default_factory, None)
+        self.assertRaises(KeyError, d1.__getitem__, 42)
         d1.default_factory = list
         d1[12].append(42)
         self.assertEqual(d1, {12: [42]})
@@ -48,14 +49,15 @@ def test_basic(self):
         self.assertRaises(TypeError, defaultdict, 1)
 
     def test_missing(self):
-        d1 = defaultdict()
-        self.assertRaises(KeyError, d1.__missing__, 42)
-        d1.default_factory = list
-        v1 = d1.__missing__(42)
-        self.assertEqual(v1, [])
-        v2 = d1.__missing__(42)
-        self.assertEqual(v2, [])
-        self.assertIsNot(v2, v1)
+        # Check that __missing__ is called when it exists
+        class A(defaultdict):
+            def __missing__(self, key):
+                return []
+        d1 = A()
+        self.assertEqual(d1.__missing__(1), [])
+        # Check that default_factory isn't called when __missing__ exists
+        d1.default_factory = dict
+        self.assertEqual(d1.__missing__(2), [])
 
     def test_repr(self):
         d1 = defaultdict()
diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c
index 90a1a586ecd6d7..0eb0fde73ed1d7 100644
--- a/Modules/_collectionsmodule.c
+++ b/Modules/_collectionsmodule.c
@@ -2222,31 +2222,56 @@ typedef struct {
 
 static PyType_Spec defdict_spec;
 
-PyDoc_STRVAR(defdict_missing_doc,
-"__missing__(key) # Called by __getitem__ for missing key; pseudo-code:\n\
-  if self.default_factory is None: raise KeyError((key,))\n\
-  self[key] = value = self.default_factory()\n\
-  return value\n\
+PyDoc_STRVAR(defdict_getitem_doc,
+"__getitem__($self, key, /)\n--\n\n\
+Return self[key]. If the item doesn't exist, it is automatically created.\n\
+The value is generated by calling either the __missing__ method (if it exists)\n\
+or the default_factory attribute (if it isn't None). If neither can be called,\n\
+a KeyError is raised.\
 ");
 
 static PyObject *
-defdict_missing(PyObject *op, PyObject *key)
+defdict_subscript(PyObject *op, PyObject *key)
 {
-    defdictobject *dd = defdictobject_CAST(op);
-    PyObject *factory = dd->default_factory;
+    PyDictObject *mp = (PyDictObject *)op;
+    Py_ssize_t ix;
+    Py_hash_t hash;
     PyObject *value;
-    if (factory == NULL || factory == Py_None) {
-        /* XXX Call dict.__missing__(key) */
-        _PyErr_SetKeyError(key);
+
+    hash = _PyObject_HashFast(key);
+    if (hash == -1) {
+        _Py_dict_unhashable_type(op, key);
         return NULL;
     }
-    value = _PyObject_CallNoArgs(factory);
-    if (value == NULL)
-        return value;
-    if (PyObject_SetItem(op, key, value) < 0) {
-        Py_DECREF(value);
-        return NULL;
+    Py_BEGIN_CRITICAL_SECTION(op);
+    ix = _Py_dict_lookup(mp, key, hash, &value);
+    if (value != NULL) {
+        Py_INCREF(value);
+    } else if (ix != DKIX_ERROR) {
+        /* Try to call self.__missing__(key) */
+        PyObject *missing;
+        int ret = PyObject_GetOptionalAttr(op, &_Py_ID(__missing__), &missing);
+        if (ret == 1) {
+            value = PyObject_CallOneArg(missing, key);
+            Py_DECREF(missing);
+        } else if (ret == 0) {
+            /* Try to call self.default_factory() */
+            PyObject *factory = defdictobject_CAST(op)->default_factory;
+            if (factory != NULL && factory != Py_None) {
+                value = _PyObject_CallNoArgs(factory);
+            } else {
+                _PyErr_SetKeyError(key);
+            }
+        }
+        /* Try to insert the new value in the dict */
+        if (value != NULL) {
+            ret = _PyDict_SetItem_KnownHash_LockHeld(mp, Py_NewRef(key),
+                                                     Py_NewRef(value), hash);
+            if (ret < 0)
+                value = NULL;
+        }
     }
+    Py_END_CRITICAL_SECTION();
     return value;
 }
 
@@ -2327,8 +2352,8 @@ defdict_reduce(PyObject *op, PyObject *Py_UNUSED(dummy))
 }
 
 static PyMethodDef defdict_methods[] = {
-    {"__missing__", defdict_missing, METH_O,
-     defdict_missing_doc},
+    {"__getitem__", defdict_subscript, METH_O|METH_COEXIST,
+     defdict_getitem_doc},
     {"copy", defdict_copy, METH_NOARGS,
      defdict_copy_doc},
     {"__copy__", defdict_copy, METH_NOARGS,
@@ -2343,7 +2368,7 @@ static PyMethodDef defdict_methods[] = {
 static PyMemberDef defdict_members[] = {
     {"default_factory", _Py_T_OBJECT,
      offsetof(defdictobject, default_factory), 0,
-     PyDoc_STR("Factory for default value called by __missing__().")},
+     PyDoc_STR("Factory for default value, called by __getitem__().")},
     {NULL}
 };
 
@@ -2507,6 +2532,7 @@ static PyType_Slot defdict_slots[] = {
     {Py_tp_init, defdict_init},
     {Py_tp_alloc, PyType_GenericAlloc},
     {Py_tp_free, PyObject_GC_Del},
+    {Py_mp_subscript, defdict_subscript},
     {0, NULL},
 };
 
diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index 09db93b2d31820..1ae4be4b234ac9 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -2398,8 +2398,8 @@ PyDict_GetItem(PyObject *op, PyObject *key)
             "PyDict_GetItemRef() or PyDict_GetItemWithError()");
 }
 
-static void
-dict_unhashable_type(PyObject *op, PyObject *key)
+void
+_Py_dict_unhashable_type(PyObject *op, PyObject *key)
 {
     PyObject *exc = PyErr_GetRaisedException();
     assert(exc != NULL);
@@ -2428,7 +2428,7 @@ _PyDict_LookupIndexAndValue(PyDictObject *mp, PyObject *key, PyObject **value)
 
     Py_hash_t hash = _PyObject_HashFast(key);
     if (hash == -1) {
-        dict_unhashable_type((PyObject*)mp, key);
+        _Py_dict_unhashable_type((PyObject*)mp, key);
         return -1;
     }
 
@@ -2532,7 +2532,7 @@ PyDict_GetItemRef(PyObject *op, PyObject *key, PyObject **result)
 
     Py_hash_t hash = _PyObject_HashFast(key);
     if (hash == -1) {
-        dict_unhashable_type(op, key);
+        _Py_dict_unhashable_type(op, key);
         *result = NULL;
         return -1;
     }
@@ -2548,7 +2548,7 @@ _PyDict_GetItemRef_Unicode_LockHeld(PyDictObject *op, PyObject *key, PyObject **
 
     Py_hash_t hash = _PyObject_HashFast(key);
     if (hash == -1) {
-        dict_unhashable_type((PyObject*)op, key);
+        _Py_dict_unhashable_type((PyObject*)op, key);
         *result = NULL;
         return -1;
     }
@@ -2586,7 +2586,7 @@ PyDict_GetItemWithError(PyObject *op, PyObject *key)
     }
     hash = _PyObject_HashFast(key);
     if (hash == -1) {
-        dict_unhashable_type(op, key);
+        _Py_dict_unhashable_type(op, key);
         return NULL;
     }
 
@@ -2746,7 +2746,7 @@ setitem_take2_lock_held(PyDictObject *mp, PyObject *key, PyObject *value)
 {
     Py_hash_t hash = _PyObject_HashFast(key);
     if (hash == -1) {
-        dict_unhashable_type((PyObject*)mp, key);
+        _Py_dict_unhashable_type((PyObject*)mp, key);
         Py_DECREF(key);
         Py_DECREF(value);
         return -1;
@@ -2924,7 +2924,7 @@ PyDict_DelItem(PyObject *op, PyObject *key)
     assert(key);
     Py_hash_t hash = _PyObject_HashFast(key);
     if (hash == -1) {
-        dict_unhashable_type(op, key);
+        _Py_dict_unhashable_type(op, key);
         return -1;
     }
 
@@ -3266,7 +3266,7 @@ pop_lock_held(PyObject *op, PyObject *key, PyObject **result)
 
     Py_hash_t hash = _PyObject_HashFast(key);
     if (hash == -1) {
-        dict_unhashable_type(op, key);
+        _Py_dict_unhashable_type(op, key);
         if (result) {
             *result = NULL;
         }
@@ -3679,7 +3679,7 @@ dict_subscript(PyObject *self, PyObject *key)
 
     hash = _PyObject_HashFast(key);
     if (hash == -1) {
-        dict_unhashable_type(self, key);
+        _Py_dict_unhashable_type(self, key);
         return NULL;
     }
     ix = _Py_dict_lookup_threadsafe(mp, key, hash, &value);
@@ -4650,7 +4650,7 @@ dict_get_impl(PyDictObject *self, PyObject *key, PyObject *default_value)
 
     hash = _PyObject_HashFast(key);
     if (hash == -1) {
-        dict_unhashable_type((PyObject*)self, key);
+        _Py_dict_unhashable_type((PyObject*)self, key);
         return NULL;
     }
     ix = _Py_dict_lookup_threadsafe(self, key, hash, &val);
@@ -4687,7 +4687,7 @@ dict_setdefault_ref_lock_held(PyObject *d, PyObject *key, PyObject *default_valu
 
     hash = _PyObject_HashFast(key);
     if (hash == -1) {
-        dict_unhashable_type(d, key);
+        _Py_dict_unhashable_type(d, key);
         if (result) {
             *result = NULL;
         }
@@ -5128,7 +5128,7 @@ dict_contains(PyObject *op, PyObject *key)
 {
     Py_hash_t hash = _PyObject_HashFast(key);
     if (hash == -1) {
-        dict_unhashable_type(op, key);
+        _Py_dict_unhashable_type(op, key);
         return -1;
     }
 
@@ -7234,7 +7234,7 @@ _PyDict_SetItem_LockHeld(PyDictObject *dict, PyObject *name, PyObject *value)
     if (value == NULL) {
         Py_hash_t hash = _PyObject_HashFast(name);
         if (hash == -1) {
-            dict_unhashable_type((PyObject*)dict, name);
+            _Py_dict_unhashable_type((PyObject*)dict, name);
             return -1;
         }
         return _PyDict_DelItem_KnownHash_LockHeld((PyObject *)dict, name, hash);
diff --git a/Python/ceval.c b/Python/ceval.c
index 967d92f4ea6855..24deb3c428f3e9 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -435,8 +435,8 @@ _PyEval_MatchKeys(PyThreadState *tstate, PyObject *map, PyObject *keys)
     PyObject *values = NULL;
     // We use the two argument form of map.get(key, default) for two reasons:
     // - Atomically check for a key and get its value without error handling.
-    // - Don't cause key creation or resizing in dict subclasses like
-    //   collections.defaultdict that define __missing__ (or similar).
+    // - Don't cause key creation or resizing in dict subclasses that define
+    //   __missing__ (or similar).
     _PyCStackRef self, method;
     _PyThreadState_PushCStackRef(tstate, &self);
     _PyThreadState_PushCStackRef(tstate, &method);

From da97340900379810f1b63335c5517052a206a0e6 Mon Sep 17 00:00:00 2001
From: Changaco <changaco@changaco.oy.lc>
Date: Tue, 21 Apr 2026 22:20:04 +0000
Subject: [PATCH 4/7] add NEWS entry

---
 .../Library/2026-04-21-22-19-35.gh-issue-148242.unTO3m.rst    | 4 ++++
 1 file changed, 4 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2026-04-21-22-19-35.gh-issue-148242.unTO3m.rst

diff --git a/Misc/NEWS.d/next/Library/2026-04-21-22-19-35.gh-issue-148242.unTO3m.rst b/Misc/NEWS.d/next/Library/2026-04-21-22-19-35.gh-issue-148242.unTO3m.rst
new file mode 100644
index 00000000000000..a4f2dcba7af144
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-04-21-22-19-35.gh-issue-148242.unTO3m.rst
@@ -0,0 +1,4 @@
+The built-in :meth:`defaultdict.__missing__` method no longer exists. A custom
+:meth:`~object.__missing__` method should no longer insert the generated value
+into the dictionary, as this is done by the new :meth:`__getitem__` method.
+defaultdict is now safe to use with :term:`free threading`.

From a86ddb4a6d937ddbc582e9dc8057f73046221c88 Mon Sep 17 00:00:00 2001
From: Changaco <changaco@changaco.oy.lc>
Date: Wed, 22 Apr 2026 17:10:15 +0000
Subject: [PATCH 5/7] fix Sphinx warnings

---
 Doc/library/collections.rst                                 | 2 +-
 .../Library/2026-04-21-22-19-35.gh-issue-148242.unTO3m.rst  | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/Doc/library/collections.rst b/Doc/library/collections.rst
index 6eacaf92f5fc75..a55b3addf26f33 100644
--- a/Doc/library/collections.rst
+++ b/Doc/library/collections.rst
@@ -767,7 +767,7 @@ stack manipulations such as ``dup``, ``drop``, ``swap``, ``over``, ``pick``,
         :pep:`584`.
 
     .. versionchanged:: 3.15
-        The built-in :meth:`defaultdict.__missing__` method no longer exists. A
+        The built-in ``defaultdict.__missing__`` method no longer exists. A
         custom :meth:`~object.__missing__` method should no longer insert the
         generated value into the dictionary, as this is done by the new
         :meth:`__getitem__` method. defaultdict is now safe to use with
diff --git a/Misc/NEWS.d/next/Library/2026-04-21-22-19-35.gh-issue-148242.unTO3m.rst b/Misc/NEWS.d/next/Library/2026-04-21-22-19-35.gh-issue-148242.unTO3m.rst
index a4f2dcba7af144..faec272d0d5f5f 100644
--- a/Misc/NEWS.d/next/Library/2026-04-21-22-19-35.gh-issue-148242.unTO3m.rst
+++ b/Misc/NEWS.d/next/Library/2026-04-21-22-19-35.gh-issue-148242.unTO3m.rst
@@ -1,4 +1,4 @@
-The built-in :meth:`defaultdict.__missing__` method no longer exists. A custom
+The built-in ``defaultdict.__missing__`` method no longer exists. A custom
 :meth:`~object.__missing__` method should no longer insert the generated value
-into the dictionary, as this is done by the new :meth:`__getitem__` method.
-defaultdict is now safe to use with :term:`free threading`.
+into the dictionary, as this is done by the new :meth:`defaultdict.__getitem__`
+method. defaultdict is now safe to use with :term:`free threading`.

From 9f641e9ad795c61620a165137a672610b970a381 Mon Sep 17 00:00:00 2001
From: Changaco <changaco@changaco.oy.lc>
Date: Wed, 22 Apr 2026 19:54:12 +0000
Subject: [PATCH 6/7] fix still broken ref in NEWS entry

---
 .../2026-04-21-22-19-35.gh-issue-148242.unTO3m.rst        | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/Misc/NEWS.d/next/Library/2026-04-21-22-19-35.gh-issue-148242.unTO3m.rst b/Misc/NEWS.d/next/Library/2026-04-21-22-19-35.gh-issue-148242.unTO3m.rst
index faec272d0d5f5f..c60a2197911806 100644
--- a/Misc/NEWS.d/next/Library/2026-04-21-22-19-35.gh-issue-148242.unTO3m.rst
+++ b/Misc/NEWS.d/next/Library/2026-04-21-22-19-35.gh-issue-148242.unTO3m.rst
@@ -1,4 +1,4 @@
-The built-in ``defaultdict.__missing__`` method no longer exists. A custom
-:meth:`~object.__missing__` method should no longer insert the generated value
-into the dictionary, as this is done by the new :meth:`defaultdict.__getitem__`
-method. defaultdict is now safe to use with :term:`free threading`.
+The built-in ``defaultdict.__missing__`` method no longer exists. A custom :meth:`~object.__missing__`
+method should no longer insert the generated value into the dictionary, as this is done by the new
+:meth:`~collections.defaultdict.__getitem__` method. defaultdict is now safe to use with
+:term:`free threading`.

From 20139ff9d785e7e81ae52fa5de01967abb73e309 Mon Sep 17 00:00:00 2001
From: Changaco <changaco@changaco.oy.lc>
Date: Wed, 22 Apr 2026 20:18:56 +0000
Subject: [PATCH 7/7] update `Doc/tools/removed-ids.txt`

---
 Doc/tools/removed-ids.txt | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Doc/tools/removed-ids.txt b/Doc/tools/removed-ids.txt
index 7bffbb8d86197d..f2ff5175960d77 100644
--- a/Doc/tools/removed-ids.txt
+++ b/Doc/tools/removed-ids.txt
@@ -3,3 +3,4 @@
 # Remove from here in 3.16
 c-api/allocation.html: deprecated-aliases
 c-api/file.html: deprecated-api
+library/collections.html: collections.defaultdict.__missing__