From e1ae6478fda0ee9df827cbc8a9fd2df0883c5608 Mon Sep 17 00:00:00 2001
From: A5rocks <git@helvetica.moe>
Date: Thu, 19 Mar 2026 13:53:47 +0900
Subject: [PATCH] Allow ParamSpec in NamedTuple and TypedDict

---
 mypy/typeanal.py                              | 16 +++++++---
 .../unit/check-parameter-specification.test   | 32 +++++++++++++++++++
 test-data/unit/fixtures/paramspec.pyi         |  4 +--
 3 files changed, 45 insertions(+), 7 deletions(-)

diff --git a/mypy/typeanal.py b/mypy/typeanal.py
index b22e1f80be592..3c36ac80aa806 100644
--- a/mypy/typeanal.py
+++ b/mypy/typeanal.py
@@ -903,8 +903,12 @@ def analyze_type_with_type_info(
             if info.special_alias:
                 return instantiate_type_alias(
                     info.special_alias,
-                    # TODO: should we allow NamedTuples generic in ParamSpec?
-                    self.anal_array(args, allow_unpack=True),
+                    self.anal_array(
+                        args,
+                        allow_unpack=True,
+                        allow_param_spec=True,
+                        allow_param_spec_literals=True,
+                    ),
                     self.fail,
                     False,
                     ctx,
@@ -921,8 +925,12 @@ def analyze_type_with_type_info(
             if info.special_alias:
                 return instantiate_type_alias(
                     info.special_alias,
-                    # TODO: should we allow TypedDicts generic in ParamSpec?
-                    self.anal_array(args, allow_unpack=True),
+                    self.anal_array(
+                        args,
+                        allow_unpack=True,
+                        allow_param_spec=True,
+                        allow_param_spec_literals=True,
+                    ),
                     self.fail,
                     False,
                     ctx,
diff --git a/test-data/unit/check-parameter-specification.test b/test-data/unit/check-parameter-specification.test
index b0808105a3858..6be1d7983a0ec 100644
--- a/test-data/unit/check-parameter-specification.test
+++ b/test-data/unit/check-parameter-specification.test
@@ -2756,3 +2756,35 @@ reveal_type(Sneaky(f8, 1, y='').kwargs)  # N: Revealed type is "builtins.dict[bu
 reveal_type(Sneaky(f9, 1, y=0).kwargs)  # N: Revealed type is "TypedDict('builtins.dict', {'x'?: builtins.int, 'y': builtins.int, 'z'?: builtins.str})"
 reveal_type(Sneaky(f9, 1, y=0, z='').kwargs)  # N: Revealed type is "TypedDict('builtins.dict', {'x'?: builtins.int, 'y': builtins.int, 'z'?: builtins.str})"
 [builtins fixtures/paramspec.pyi]
+
+[case testNamedTupleAndTypedDictParamSpecInteraction]
+# https://github.com/python/mypy/issues/21039
+from typing import Callable, NamedTuple, TypedDict, ParamSpec, Generic
+
+P = ParamSpec("P")
+
+class X(TypedDict, Generic[P]):
+    c: Callable[P, None]
+
+def f1(y: X[P]) -> None: ...
+def f2(y: X[[int]]) -> None: ...
+def f3(y: X[...]) -> None: ...
+
+x1: X[[str]]
+f1(x1)
+f2(x1)  # E: Argument 1 to "f2" has incompatible type "X[[str]]"; expected "X[[int]]"
+f3(x1)
+
+class Y(NamedTuple, Generic[P]):
+    c: Callable[P, None]
+
+def g1(y: Y[P]) -> None: ...
+def g2(y: Y[[int]]) -> None: ...
+def g3(y: Y[...]) -> None: ...
+
+y1: Y[[str]]
+g1(y1)
+g2(y1)  # E: Argument 1 to "g2" has incompatible type "Y[[str]]"; expected "Y[[int]]"
+g3(y1)
+[builtins fixtures/paramspec.pyi]
+[typing fixtures/typing-full.pyi]
diff --git a/test-data/unit/fixtures/paramspec.pyi b/test-data/unit/fixtures/paramspec.pyi
index a61e5b66ae24a..af2331dbdc5d5 100644
--- a/test-data/unit/fixtures/paramspec.pyi
+++ b/test-data/unit/fixtures/paramspec.pyi
@@ -51,8 +51,6 @@ class tuple(Sequence[T_co], Generic[T_co]):
     def __len__(self) -> int: ...
     def count(self, obj: object) -> int: ...
 
-class _ItemsView(Iterable[Tuple[KT, VT]]): ...
-
 class dict(Mapping[KT, VT]):
     @overload
     def __init__(self, **kwargs: VT) -> None: ...
@@ -71,7 +69,7 @@ class dict(Mapping[KT, VT]):
     def get(self, key: KT, default: T, /) -> Union[VT, T]: ...
     def __len__(self) -> int: ...
     def pop(self, k: KT) -> VT: ...
-    def items(self) -> _ItemsView[KT, VT]: ...
+    def items(self) -> Iterable[Tuple[KT, VT]]: ...
 
 def isinstance(x: object, t: type) -> bool: ...