Normalise use of Never vs NoReturn (#8549)

Author: AlexWaygood

stdlib/asyncio/mixins.pyi

@@ -1,9 +1,9 @@
 import sys
 import threading
-from typing import NoReturn
+from typing_extensions import Never
 
 _global_lock: threading.Lock
 
 class _LoopBoundMixin:
     if sys.version_info < (3, 11):
-        def __init__(self, *, loop: NoReturn = ...) -> None: ...
+        def __init__(self, *, loop: Never = ...) -> None: ...

stdlib/typing.pyi

@@ -18,7 +18,7 @@ from types import (
     TracebackType,
     WrapperDescriptorType,
 )
-from typing_extensions import ParamSpec as _ParamSpec, final as _final
+from typing_extensions import Never as _Never, ParamSpec as _ParamSpec, final as _final
 
 __all__ = [
     "AbstractSet",
@@ -791,13 +791,13 @@ class _TypedDict(Mapping[str, object], metaclass=ABCMeta):
         __required_keys__: ClassVar[frozenset[str]]
         __optional_keys__: ClassVar[frozenset[str]]
     def copy(self: _typeshed.Self) -> _typeshed.Self: ...
-    # Using NoReturn so that only calls using mypy plugin hook that specialize the signature
+    # Using Never so that only calls using mypy plugin hook that specialize the signature
     # can go through.
-    def setdefault(self, k: NoReturn, default: object) -> object: ...
+    def setdefault(self, k: _Never, default: object) -> object: ...
     # Mypy plugin hook for 'pop' expects that 'default' has a type variable type.
-    def pop(self, k: NoReturn, default: _T = ...) -> object: ...  # pyright: ignore[reportInvalidTypeVarUse]
+    def pop(self, k: _Never, default: _T = ...) -> object: ...  # pyright: ignore[reportInvalidTypeVarUse]
     def update(self: _T, __m: _T) -> None: ...
-    def __delitem__(self, k: NoReturn) -> None: ...
+    def __delitem__(self, k: _Never) -> None: ...
     def items(self) -> dict_items[str, object]: ...
     def keys(self) -> dict_keys[str, object]: ...
     def values(self) -> dict_values[str, object]: ...

stdlib/typing_extensions.pyi

@@ -127,16 +127,16 @@ class _TypedDict(Mapping[str, object], metaclass=abc.ABCMeta):
     __optional_keys__: ClassVar[frozenset[str]]
     __total__: ClassVar[bool]
     def copy(self: _typeshed.Self) -> _typeshed.Self: ...
-    # Using NoReturn so that only calls using mypy plugin hook that specialize the signature
+    # Using Never so that only calls using mypy plugin hook that specialize the signature
     # can go through.
-    def setdefault(self, k: NoReturn, default: object) -> object: ...
+    def setdefault(self, k: Never, default: object) -> object: ...
     # Mypy plugin hook for 'pop' expects that 'default' has a type variable type.
-    def pop(self, k: NoReturn, default: _T = ...) -> object: ...  # pyright: ignore[reportInvalidTypeVarUse]
+    def pop(self, k: Never, default: _T = ...) -> object: ...  # pyright: ignore[reportInvalidTypeVarUse]
     def update(self: _T, __m: _T) -> None: ...
     def items(self) -> dict_items[str, object]: ...
     def keys(self) -> dict_keys[str, object]: ...
     def values(self) -> dict_values[str, object]: ...
-    def __delitem__(self, k: NoReturn) -> None: ...
+    def __delitem__(self, k: Never) -> None: ...
     if sys.version_info >= (3, 9):
         def __or__(self: _typeshed.Self, __value: _typeshed.Self) -> _typeshed.Self: ...
         def __ior__(self: _typeshed.Self, __value: _typeshed.Self) -> _typeshed.Self: ...
@@ -221,9 +221,9 @@ if sys.version_info >= (3, 11):
     )
 else:
     Self: _SpecialForm
-    Never: _SpecialForm
+    Never: _SpecialForm = ...
     def reveal_type(__obj: _T) -> _T: ...
-    def assert_never(__arg: NoReturn) -> NoReturn: ...
+    def assert_never(__arg: Never) -> Never: ...
     def assert_type(__val: _T, __typ: Any) -> _T: ...
     def clear_overloads() -> None: ...
     def get_overloads(func: Callable[..., object]) -> Sequence[Callable[..., object]]: ...

stubs/mypy-extensions/mypy_extensions.pyi

@@ -4,6 +4,7 @@ from _collections_abc import dict_items, dict_keys, dict_values
 from _typeshed import IdentityFunction, Self
 from collections.abc import Mapping
 from typing import Any, ClassVar, Generic, TypeVar, overload, type_check_only
+from typing_extensions import Never
 
 _T = TypeVar("_T")
 _U = TypeVar("_U")
@@ -16,16 +17,16 @@ class _TypedDict(Mapping[str, object], metaclass=abc.ABCMeta):
     # Unlike typing(_extensions).TypedDict,
     # subclasses of mypy_extensions.TypedDict do NOT have the __required_keys__ and __optional_keys__ ClassVars
     def copy(self: Self) -> Self: ...
-    # Using NoReturn so that only calls using mypy plugin hook that specialize the signature
+    # Using Never so that only calls using mypy plugin hook that specialize the signature
     # can go through.
-    def setdefault(self, k: NoReturn, default: object) -> object: ...
+    def setdefault(self, k: Never, default: object) -> object: ...
     # Mypy plugin hook for 'pop' expects that 'default' has a type variable type.
-    def pop(self, k: NoReturn, default: _T = ...) -> object: ...  # pyright: ignore[reportInvalidTypeVarUse]
+    def pop(self, k: Never, default: _T = ...) -> object: ...  # pyright: ignore[reportInvalidTypeVarUse]
     def update(self: Self, __m: Self) -> None: ...
     def items(self) -> dict_items[str, object]: ...
     def keys(self) -> dict_keys[str, object]: ...
     def values(self) -> dict_values[str, object]: ...
-    def __delitem__(self, k: NoReturn) -> None: ...
+    def __delitem__(self, k: Never) -> None: ...
     if sys.version_info >= (3, 9):
         def __or__(self: Self, __other: Self) -> Self: ...
         def __ior__(self: Self, __other: Self) -> Self: ...