pythongh-145099: Fix frozendict.__doc__ using dict's docstring

PyFrozenDict_Type.tp_doc was set to `dictionary_doc`, which describes
`dict()` — saying "dict() -> new empty dictionary" throughout. Since
frozendict is a separate type, it needs its own docstring. Add a
`frozendict_doc` with correct "frozendict()" references and a note
that frozendict is immutable and hashable.

https://claude.ai/code/session_01EdeU6enhg5YoLvKmBPpiZf

Author: claude

Lib/test/test_dict.py

@@ -1803,6 +1803,11 @@ def test_hash(self):
         with self.assertRaisesRegex(TypeError, "unhashable type: 'list'"):
             hash(fd)
 
+    def test_doc(self):
+        # frozendict.__doc__ must mention "frozendict", not "dict"
+        self.assertIn("frozendict", frozendict.__doc__)
+        self.assertNotIn("dict() ->", frozendict.__doc__)
+
     def test_fromkeys(self):
         self.assertEqual(frozendict.fromkeys('abc'),
                          frozendict(a=None, b=None, c=None))

Objects/dictobject.c

@@ -8123,6 +8123,19 @@ PyFrozenDict_New(PyObject *iterable)
 }
 
 
+PyDoc_STRVAR(frozendict_doc,
+"frozendict() -> new empty frozendict\n"
+"frozendict(mapping) -> new frozendict initialized from a mapping object's\n"
+"    (key, value) pairs\n"
+"frozendict(iterable) -> new frozendict initialized as if via:\n"
+"    d = {}\n"
+"    for k, v in iterable:\n"
+"        d[k] = v\n"
+"frozendict(**kwargs) -> new frozendict initialized with the name=value pairs\n"
+"    in the keyword argument list.  For example:  frozendict(one=1, two=2)\n"
+"\n"
+"Unlike dict, frozendict is immutable and hashable.");
+
 PyTypeObject PyFrozenDict_Type = {
     PyVarObject_HEAD_INIT(&PyType_Type, 0)
     .tp_name = "frozendict",
@@ -8137,7 +8150,7 @@ PyTypeObject PyFrozenDict_Type = {
     .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC
                 | Py_TPFLAGS_BASETYPE
                 | _Py_TPFLAGS_MATCH_SELF | Py_TPFLAGS_MAPPING,
-    .tp_doc = dictionary_doc,
+    .tp_doc = frozendict_doc,
     .tp_traverse = dict_traverse,
     .tp_clear = dict_tp_clear,
     .tp_richcompare = dict_richcompare,