feat: https://github.com/pandas-dev/pandas/blob/v2.3.1/pandas/core/common.py#L416-L417

Author: cmp0xff

pandas-stubs/core/frame.pyi

@@ -2,6 +2,7 @@ from builtins import (
     bool as _bool,
     str as _str,
 )
+from collections import defaultdict
 from collections.abc import (
     Callable,
     Hashable,
@@ -395,6 +396,14 @@ class DataFrame(NDFrame, OpsMixin, _GetItemHack):
         na_value: Scalar = ...,
     ) -> np.ndarray: ...
     @overload
+    def to_dict(
+        self,
+        orient=...,
+        *,
+        into: type[defaultdict],
+        index: Literal[True] = ...,
+    ) -> Never: ...
+    @overload
     def to_dict(
         self,
         orient: Literal["records"],

tests/test_frame.py

@@ -2,6 +2,7 @@
 
 from collections import defaultdict
 from collections.abc import (
+    Callable,
     Hashable,
     Iterable,
     Iterator,
@@ -20,7 +21,6 @@
 from typing import (
     TYPE_CHECKING,
     Any,
-    Callable,
     Generic,
     TypedDict,
     TypeVar,
@@ -39,6 +39,7 @@
 )
 import pytest
 from typing_extensions import (
+    Never,
     TypeAlias,
     assert_never,
     assert_type,
@@ -3650,6 +3651,15 @@ def test(mapping: Mapping) -> None:  # pyright: ignore[reportUnusedFunction]
                 into=mapping  # pyright: ignore[reportArgumentType,reportCallIssue]
             )
 
+        assert_type(DF.to_dict(into=defaultdict), Never)
+        assert_type(DF.to_dict("records", into=defaultdict), Never)
+        assert_type(DF.to_dict("index", into=defaultdict), Never)
+        assert_type(DF.to_dict("dict", into=defaultdict), Never)
+        assert_type(DF.to_dict("list", into=defaultdict), Never)
+        assert_type(DF.to_dict("series", into=defaultdict), Never)
+        assert_type(DF.to_dict("split", into=defaultdict), Never)
+        assert_type(DF.to_dict("tight", into=defaultdict), Never)
+
 
 def test_to_dict_into_defaultdict_any() -> None:
     """Test DataFrame.to_dict with `into=defaultdict[Any, list]`"""