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gh-138949: Fix non-generic children of generic TypedDicts with future annotations by sobolevn · Pull Request #150762 · python/cpython · GitHub

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gh-138949: Fix non-generic children of generic TypedDicts with future annotations #150762

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gh-138949: Fix non-generic children of generic TypedDicts with future annotations #150762

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37 changes: 37 additions & 0 deletions Lib/test/test_typing.py
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Original file line number Diff line number Diff line change
Expand Up @@ -5364,6 +5364,43 @@ def test_pep_695_generics_with_future_annotations_nested_in_function(self):
set(results.generic_func.__type_params__)
)

def test_pep695_generic_class_with_future_typed_dicts(self):
# gh-138949
td1_hints = get_type_hints(ann_module695.TD1)
self.assertEqual(td1_hints, {'a': ann_module695.TD1.__type_params__[0]})

td2_hints = get_type_hints(ann_module695.TD2) # used to fail with `NameError`
self.assertEqual(
td2_hints,
{'a': ann_module695.TD1.__type_params__[0], 'b': int},
)

td3_hints = get_type_hints(ann_module695.TD3)
self.assertEqual(
td3_hints,
{
'a': ann_module695.TD1.__type_params__[0],
'b': int,
'c': ann_module695.TD3.__type_params__[0],
},
)

td4_hints = get_type_hints(ann_module695.TD4)
self.assertEqual(
td4_hints,
{
# Type param `TD4.T` must have a higher precedence over `TD1.T`:
'a': ann_module695.TD4.__type_params__[0],
'b': int,
'c': ann_module695.TD3.__type_params__[0],
'd': ann_module695.TD4.__type_params__[0],
'e': ann_module695.TD4.__type_params__[1],
},
)

with self.assertRaisesRegex(NameError, "name 'T' is not defined"):
get_type_hints(ann_module695.TD1_2)

def test_extended_generic_rules_subclassing(self):
class T1(Tuple[T, KT]): ...
class T2(Tuple[T, ...]): ...
Expand Down
21 changes: 20 additions & 1 deletion Lib/test/typinganndata/ann_module695.py
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
from __future__ import annotations
from typing import Callable
from typing import Callable, TypedDict


class A[T, *Ts, **P]:
Expand Down Expand Up @@ -70,3 +70,22 @@ def generic_function[Eggs, **Spam](x: Eggs, y: Spam): pass
generic_func=generic_function,
hints_for_generic_func=get_type_hints(generic_function)
)

# gh-138949
class TD1[T](TypedDict):
a: T

class TD2(TD1):
b: int

class TD3[CT](TD2):
c: CT

class TD4[T, E](TD3):
d: T
e: E

class TD1_2(TD1):
# This must raise a `NameError`, because `T` is only defined for a parent
# keys scope.
b: T
30 changes: 27 additions & 3 deletions Lib/typing.py
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Original file line number Diff line number Diff line change
Expand Up @@ -449,9 +449,33 @@ def _eval_type(t, globalns, localns, type_params, *, recursive_guard=frozenset()
# prefer_fwd_module flag), so that the default behavior remains more straightforward.
if prefer_fwd_module and t.__forward_module__ is not None:
globalns = None
# If there are type params on the owner, we need to add them back, because
# annotationlib won't.
if owner_type_params := getattr(owner, "__type_params__", None):
# # If there are type params on the owner, we need to add them back, because
# # annotationlib won't.
owner_type_params = getattr(owner, "__type_params__", ())
# TypedDict classes copy the parent type annotations, but do not
# copy parent type params / mro. So, we need to collect them manually here.
if is_typeddict(owner):
owner_type_params = list(owner_type_params)
mro_stack = list(owner.__orig_bases__)
seen = {tp.__name__ for tp in owner_type_params}
while mro_stack:
typ = mro_stack.pop(0)
if is_typeddict(typ):
mro_stack.extend(typ.__orig_bases__)
if t not in typ.__annotations__.values():
# We only copy __type_params__ for types that own
# this annotation. So, it won't be possible to use
# undeclared type parameters from parent types in children.
continue

base_type_params = getattr(typ, "__type_params__", ())
for btp in base_type_params:
if btp.__name__ in seen:

JelleZijlstra Jun 2, 2026

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Choose a reason Spam Abuse Off Topic Outdated Duplicate Resolved Low Quality

this seems wrong, base classes can have another type param with the same name
continue
owner_type_params.append(btp)
seen.add(btp.__name__)
owner_type_params = tuple(owner_type_params)
if owner_type_params:
globalns = getattr(
sys.modules.get(t.__forward_module__, None), "__dict__", None
)
Expand Down
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Library/2026-06-02-10-38-48.gh-issue-138949.KI54me.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Fix :exc:`NameError` in :func:`typing.get_type_hints` on non-generic
children of generic typed dicts with future annotations flag enabled.
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