Merge pull request #19118 from BvB93/sty

MAINT: Misc cleaning of `numpy.typing`

9 files changed, 231 insertions, 232 deletions

diff --git a/numpy/typing/__init__.py b/numpy/typing/__init__.py
index 1bfdf07ae..04d34f0c7 100644
--- a/numpy/typing/__init__.py
+++ b/numpy/typing/__init__.py
@@ -164,11 +164,19 @@ API
 from typing import TYPE_CHECKING, List
 
 if TYPE_CHECKING:
-    import sys
-    if sys.version_info >= (3, 8):
-        from typing import final
+    # typing_extensions is always available when type-checking
+    from typing_extensions import Literal as L
+    _HAS_TYPING_EXTENSIONS: L[True]
+else:
+    try:
+        import typing_extensions
+    except ImportError:
+        _HAS_TYPING_EXTENSIONS = False
     else:
-        from typing_extensions import final
+        _HAS_TYPING_EXTENSIONS = True
+
+if TYPE_CHECKING:
+    from typing_extensions import final
 else:
     def final(f): return f
 
@@ -204,14 +212,14 @@ class NBitBase:
     .. code-block:: python
 
         >>> from __future__ import annotations
-        >>> from typing import TypeVar, Union, TYPE_CHECKING
+        >>> from typing import TypeVar, TYPE_CHECKING
         >>> import numpy as np
         >>> import numpy.typing as npt
 
         >>> T1 = TypeVar("T1", bound=npt.NBitBase)
         >>> T2 = TypeVar("T2", bound=npt.NBitBase)
 
-        >>> def add(a: np.floating[T1], b: np.integer[T2]) -> np.floating[Union[T1, T2]]:
+        >>> def add(a: np.floating[T1], b: np.integer[T2]) -> np.floating[T1 | T2]:
         ...     return a + b
 
         >>> a = np.float16()
@@ -352,6 +360,7 @@ from ._array_like import (
 )
 from ._generic_alias import (
     NDArray as NDArray,
+    _DType,
     _GenericAlias,
 )
 
diff --git a/numpy/typing/_array_like.py b/numpy/typing/_array_like.py
index 2283c98d7..2b823ecc0 100644
--- a/numpy/typing/_array_like.py
+++ b/numpy/typing/_array_like.py
@@ -21,23 +21,20 @@ from numpy import (
     bytes_,
 )
 
+from . import _HAS_TYPING_EXTENSIONS
+from ._dtype_like import DTypeLike
+
 if sys.version_info >= (3, 8):
     from typing import Protocol
-    HAVE_PROTOCOL = True
-else:
-    try:
-        from typing_extensions import Protocol
-    except ImportError:
-        HAVE_PROTOCOL = False
-    else:
-        HAVE_PROTOCOL = True
+elif _HAS_TYPING_EXTENSIONS:
+    from typing_extensions import Protocol
 
 _T = TypeVar("_T")
 _ScalarType = TypeVar("_ScalarType", bound=generic)
 _DType = TypeVar("_DType", bound="dtype[Any]")
 _DType_co = TypeVar("_DType_co", covariant=True, bound="dtype[Any]")
 
-if TYPE_CHECKING or HAVE_PROTOCOL:
+if TYPE_CHECKING or _HAS_TYPING_EXTENSIONS:
     # The `_SupportsArray` protocol only cares about the default dtype
     # (i.e. `dtype=None` or no `dtype` parameter at all) of the to-be returned
     # array.
diff --git a/numpy/typing/_callable.py b/numpy/typing/_callable.py
index 8f838f1ae..54f9b1425 100644
--- a/numpy/typing/_callable.py
+++ b/numpy/typing/_callable.py
@@ -45,21 +45,15 @@ from ._scalars import (
     _FloatLike_co,
     _NumberLike_co,
 )
-from . import NBitBase
+from . import NBitBase, _HAS_TYPING_EXTENSIONS
 from ._generic_alias import NDArray
 
 if sys.version_info >= (3, 8):
     from typing import Protocol
-    HAVE_PROTOCOL = True
-else:
-    try:
-        from typing_extensions import Protocol
-    except ImportError:
-        HAVE_PROTOCOL = False
-    else:
-        HAVE_PROTOCOL = True
-
-if TYPE_CHECKING or HAVE_PROTOCOL:
+elif _HAS_TYPING_EXTENSIONS:
+    from typing_extensions import Protocol
+
+if TYPE_CHECKING or _HAS_TYPING_EXTENSIONS:
     _T1 = TypeVar("_T1")
     _T2 = TypeVar("_T2")
     _2Tuple = Tuple[_T1, _T1]
@@ -108,7 +102,7 @@ if TYPE_CHECKING or HAVE_PROTOCOL:
 
     class _BoolTrueDiv(Protocol):
         @overload
-        def __call__(self, __other: Union[float, _IntLike_co]) -> float64: ...
+        def __call__(self, __other: float | _IntLike_co) -> float64: ...
         @overload
         def __call__(self, __other: complex) -> complex128: ...
         @overload
@@ -132,7 +126,7 @@ if TYPE_CHECKING or HAVE_PROTOCOL:
         @overload  # platform dependent
         def __call__(self, __other: int) -> _2Tuple[int_]: ...
         @overload
-        def __call__(self, __other: float) -> _2Tuple[floating[Union[_NBit1, _NBitDouble]]]: ...
+        def __call__(self, __other: float) -> _2Tuple[floating[_NBit1 | _NBitDouble]]: ...
         @overload
         def __call__(self, __other: _IntType) -> _2Tuple[_IntType]: ...
         @overload
@@ -150,15 +144,15 @@ if TYPE_CHECKING or HAVE_PROTOCOL:
         @overload
         def __call__(self, __other: bool) -> floating[_NBit1]: ...
         @overload
-        def __call__(self, __other: int) -> floating[Union[_NBit1, _NBitInt]]: ...
+        def __call__(self, __other: int) -> floating[_NBit1 | _NBitInt]: ...
         @overload
-        def __call__(self, __other: float) -> floating[Union[_NBit1, _NBitDouble]]: ...
+        def __call__(self, __other: float) -> floating[_NBit1 | _NBitDouble]: ...
         @overload
         def __call__(
             self, __other: complex
-        ) -> complexfloating[Union[_NBit1, _NBitDouble], Union[_NBit1, _NBitDouble]]: ...
+        ) -> complexfloating[_NBit1 | _NBitDouble, _NBit1 | _NBitDouble]: ...
         @overload
-        def __call__(self, __other: integer[_NBit2]) -> floating[Union[_NBit1, _NBit2]]: ...
+        def __call__(self, __other: integer[_NBit2]) -> floating[_NBit1 | _NBit2]: ...
 
     class _UnsignedIntOp(Protocol[_NBit1]):
         # NOTE: `uint64 + signedinteger -> float64`
@@ -166,18 +160,18 @@ if TYPE_CHECKING or HAVE_PROTOCOL:
         def __call__(self, __other: bool) -> unsignedinteger[_NBit1]: ...
         @overload
         def __call__(
-            self, __other: Union[int, signedinteger[Any]]
+            self, __other: int | signedinteger[Any]
         ) -> Any: ...
         @overload
-        def __call__(self, __other: float) -> floating[Union[_NBit1, _NBitDouble]]: ...
+        def __call__(self, __other: float) -> floating[_NBit1 | _NBitDouble]: ...
         @overload
         def __call__(
             self, __other: complex
-        ) -> complexfloating[Union[_NBit1, _NBitDouble], Union[_NBit1, _NBitDouble]]: ...
+        ) -> complexfloating[_NBit1 | _NBitDouble, _NBit1 | _NBitDouble]: ...
         @overload
         def __call__(
             self, __other: unsignedinteger[_NBit2]
-        ) -> unsignedinteger[Union[_NBit1, _NBit2]]: ...
+        ) -> unsignedinteger[_NBit1 | _NBit2]: ...
 
     class _UnsignedIntBitOp(Protocol[_NBit1]):
         @overload
@@ -189,135 +183,135 @@ if TYPE_CHECKING or HAVE_PROTOCOL:
         @overload
         def __call__(
             self, __other: unsignedinteger[_NBit2]
-        ) -> unsignedinteger[Union[_NBit1, _NBit2]]: ...
+        ) -> unsignedinteger[_NBit1 | _NBit2]: ...
 
     class _UnsignedIntMod(Protocol[_NBit1]):
         @overload
         def __call__(self, __other: bool) -> unsignedinteger[_NBit1]: ...
         @overload
         def __call__(
-            self, __other: Union[int, signedinteger[Any]]
+            self, __other: int | signedinteger[Any]
         ) -> Any: ...
         @overload
-        def __call__(self, __other: float) -> floating[Union[_NBit1, _NBitDouble]]: ...
+        def __call__(self, __other: float) -> floating[_NBit1 | _NBitDouble]: ...
         @overload
         def __call__(
             self, __other: unsignedinteger[_NBit2]
-        ) -> unsignedinteger[Union[_NBit1, _NBit2]]: ...
+        ) -> unsignedinteger[_NBit1 | _NBit2]: ...
 
     class _UnsignedIntDivMod(Protocol[_NBit1]):
         @overload
         def __call__(self, __other: bool) -> _2Tuple[signedinteger[_NBit1]]: ...
         @overload
         def __call__(
-            self, __other: Union[int, signedinteger[Any]]
+            self, __other: int | signedinteger[Any]
         ) -> _2Tuple[Any]: ...
         @overload
-        def __call__(self, __other: float) -> _2Tuple[floating[Union[_NBit1, _NBitDouble]]]: ...
+        def __call__(self, __other: float) -> _2Tuple[floating[_NBit1 | _NBitDouble]]: ...
         @overload
         def __call__(
             self, __other: unsignedinteger[_NBit2]
-        ) -> _2Tuple[unsignedinteger[Union[_NBit1, _NBit2]]]: ...
+        ) -> _2Tuple[unsignedinteger[_NBit1 | _NBit2]]: ...
 
     class _SignedIntOp(Protocol[_NBit1]):
         @overload
         def __call__(self, __other: bool) -> signedinteger[_NBit1]: ...
         @overload
-        def __call__(self, __other: int) -> signedinteger[Union[_NBit1, _NBitInt]]: ...
+        def __call__(self, __other: int) -> signedinteger[_NBit1 | _NBitInt]: ...
         @overload
-        def __call__(self, __other: float) -> floating[Union[_NBit1, _NBitDouble]]: ...
+        def __call__(self, __other: float) -> floating[_NBit1 | _NBitDouble]: ...
         @overload
         def __call__(
             self, __other: complex
-        ) -> complexfloating[Union[_NBit1, _NBitDouble], Union[_NBit1, _NBitDouble]]: ...
+        ) -> complexfloating[_NBit1 | _NBitDouble, _NBit1 | _NBitDouble]: ...
         @overload
         def __call__(
             self, __other: signedinteger[_NBit2]
-        ) -> signedinteger[Union[_NBit1, _NBit2]]: ...
+        ) -> signedinteger[_NBit1 | _NBit2]: ...
 
     class _SignedIntBitOp(Protocol[_NBit1]):
         @overload
         def __call__(self, __other: bool) -> signedinteger[_NBit1]: ...
         @overload
-        def __call__(self, __other: int) -> signedinteger[Union[_NBit1, _NBitInt]]: ...
+        def __call__(self, __other: int) -> signedinteger[_NBit1 | _NBitInt]: ...
         @overload
         def __call__(
             self, __other: signedinteger[_NBit2]
-        ) -> signedinteger[Union[_NBit1, _NBit2]]: ...
+        ) -> signedinteger[_NBit1 | _NBit2]: ...
 
     class _SignedIntMod(Protocol[_NBit1]):
         @overload
         def __call__(self, __other: bool) -> signedinteger[_NBit1]: ...
         @overload
-        def __call__(self, __other: int) -> signedinteger[Union[_NBit1, _NBitInt]]: ...
+        def __call__(self, __other: int) -> signedinteger[_NBit1 | _NBitInt]: ...
         @overload
-        def __call__(self, __other: float) -> floating[Union[_NBit1, _NBitDouble]]: ...
+        def __call__(self, __other: float) -> floating[_NBit1 | _NBitDouble]: ...
         @overload
         def __call__(
             self, __other: signedinteger[_NBit2]
-        ) -> signedinteger[Union[_NBit1, _NBit2]]: ...
+        ) -> signedinteger[_NBit1 | _NBit2]: ...
 
     class _SignedIntDivMod(Protocol[_NBit1]):
         @overload
         def __call__(self, __other: bool) -> _2Tuple[signedinteger[_NBit1]]: ...
         @overload
-        def __call__(self, __other: int) -> _2Tuple[signedinteger[Union[_NBit1, _NBitInt]]]: ...
+        def __call__(self, __other: int) -> _2Tuple[signedinteger[_NBit1 | _NBitInt]]: ...
         @overload
-        def __call__(self, __other: float) -> _2Tuple[floating[Union[_NBit1, _NBitDouble]]]: ...
+        def __call__(self, __other: float) -> _2Tuple[floating[_NBit1 | _NBitDouble]]: ...
         @overload
         def __call__(
             self, __other: signedinteger[_NBit2]
-        ) -> _2Tuple[signedinteger[Union[_NBit1, _NBit2]]]: ...
+        ) -> _2Tuple[signedinteger[_NBit1 | _NBit2]]: ...
 
     class _FloatOp(Protocol[_NBit1]):
         @overload
         def __call__(self, __other: bool) -> floating[_NBit1]: ...
         @overload
-        def __call__(self, __other: int) -> floating[Union[_NBit1, _NBitInt]]: ...
+        def __call__(self, __other: int) -> floating[_NBit1 | _NBitInt]: ...
         @overload
-        def __call__(self, __other: float) -> floating[Union[_NBit1, _NBitDouble]]: ...
+        def __call__(self, __other: float) -> floating[_NBit1 | _NBitDouble]: ...
         @overload
         def __call__(
             self, __other: complex
-        ) -> complexfloating[Union[_NBit1, _NBitDouble], Union[_NBit1, _NBitDouble]]: ...
+        ) -> complexfloating[_NBit1 | _NBitDouble, _NBit1 | _NBitDouble]: ...
         @overload
         def __call__(
-            self, __other: Union[integer[_NBit2], floating[_NBit2]]
-        ) -> floating[Union[_NBit1, _NBit2]]: ...
+            self, __other: integer[_NBit2] | floating[_NBit2]
+        ) -> floating[_NBit1 | _NBit2]: ...
 
     class _FloatMod(Protocol[_NBit1]):
         @overload
         def __call__(self, __other: bool) -> floating[_NBit1]: ...
         @overload
-        def __call__(self, __other: int) -> floating[Union[_NBit1, _NBitInt]]: ...
+        def __call__(self, __other: int) -> floating[_NBit1 | _NBitInt]: ...
         @overload
-        def __call__(self, __other: float) -> floating[Union[_NBit1, _NBitDouble]]: ...
+        def __call__(self, __other: float) -> floating[_NBit1 | _NBitDouble]: ...
         @overload
         def __call__(
-            self, __other: Union[integer[_NBit2], floating[_NBit2]]
-        ) -> floating[Union[_NBit1, _NBit2]]: ...
+            self, __other: integer[_NBit2] | floating[_NBit2]
+        ) -> floating[_NBit1 | _NBit2]: ...
 
     class _FloatDivMod(Protocol[_NBit1]):
         @overload
         def __call__(self, __other: bool) -> _2Tuple[floating[_NBit1]]: ...
         @overload
-        def __call__(self, __other: int) -> _2Tuple[floating[Union[_NBit1, _NBitInt]]]: ...
+        def __call__(self, __other: int) -> _2Tuple[floating[_NBit1 | _NBitInt]]: ...
         @overload
-        def __call__(self, __other: float) -> _2Tuple[floating[Union[_NBit1, _NBitDouble]]]: ...
+        def __call__(self, __other: float) -> _2Tuple[floating[_NBit1 | _NBitDouble]]: ...
         @overload
         def __call__(
-            self, __other: Union[integer[_NBit2], floating[_NBit2]]
-        ) -> _2Tuple[floating[Union[_NBit1, _NBit2]]]: ...
+            self, __other: integer[_NBit2] | floating[_NBit2]
+        ) -> _2Tuple[floating[_NBit1 | _NBit2]]: ...
 
     class _ComplexOp(Protocol[_NBit1]):
         @overload
         def __call__(self, __other: bool) -> complexfloating[_NBit1, _NBit1]: ...
         @overload
-        def __call__(self, __other: int) -> complexfloating[Union[_NBit1, _NBitInt], Union[_NBit1, _NBitInt]]: ...
+        def __call__(self, __other: int) -> complexfloating[_NBit1 | _NBitInt, _NBit1 | _NBitInt]: ...
         @overload
         def __call__(
-            self, __other: Union[float, complex]
-        ) -> complexfloating[Union[_NBit1, _NBitDouble], Union[_NBit1, _NBitDouble]]: ...
+            self, __other: complex
+        ) -> complexfloating[_NBit1 | _NBitDouble, _NBit1 | _NBitDouble]: ...
         @overload
         def __call__(
             self,
@@ -326,7 +320,7 @@ if TYPE_CHECKING or HAVE_PROTOCOL:
                 floating[_NBit2],
                 complexfloating[_NBit2, _NBit2],
             ]
-        ) -> complexfloating[Union[_NBit1, _NBit2], Union[_NBit1, _NBit2]]: ...
+        ) -> complexfloating[_NBit1 | _NBit2, _NBit1 | _NBit2]: ...
 
     class _NumberOp(Protocol):
         def __call__(self, __other: _NumberLike_co) -> Any: ...
@@ -338,25 +332,25 @@ if TYPE_CHECKING or HAVE_PROTOCOL:
         def __call__(self, __other: _T2) -> NDArray[bool_]: ...
 
 else:
-    _BoolOp = Any
-    _BoolBitOp = Any
-    _BoolSub = Any
-    _BoolTrueDiv = Any
-    _BoolMod = Any
-    _BoolDivMod = Any
-    _TD64Div = Any
-    _IntTrueDiv = Any
-    _UnsignedIntOp = Any
-    _UnsignedIntBitOp = Any
-    _UnsignedIntMod = Any
-    _UnsignedIntDivMod = Any
-    _SignedIntOp = Any
-    _SignedIntBitOp = Any
-    _SignedIntMod = Any
-    _SignedIntDivMod = Any
-    _FloatOp = Any
-    _FloatMod = Any
-    _FloatDivMod = Any
-    _ComplexOp = Any
-    _NumberOp = Any
-    _ComparisonOp = Any
+    _BoolOp = NotImplemented
+    _BoolBitOp = NotImplemented
+    _BoolSub = NotImplemented
+    _BoolTrueDiv = NotImplemented
+    _BoolMod = NotImplemented
+    _BoolDivMod = NotImplemented
+    _TD64Div = NotImplemented
+    _IntTrueDiv = NotImplemented
+    _UnsignedIntOp = NotImplemented
+    _UnsignedIntBitOp = NotImplemented
+    _UnsignedIntMod = NotImplemented
+    _UnsignedIntDivMod = NotImplemented
+    _SignedIntOp = NotImplemented
+    _SignedIntBitOp = NotImplemented
+    _SignedIntMod = NotImplemented
+    _SignedIntDivMod = NotImplemented
+    _FloatOp = NotImplemented
+    _FloatMod = NotImplemented
+    _FloatDivMod = NotImplemented
+    _ComplexOp = NotImplemented
+    _NumberOp = NotImplemented
+    _ComparisonOp = NotImplemented
diff --git a/numpy/typing/_char_codes.py b/numpy/typing/_char_codes.py
index 6b6f7ae88..6b33f995d 100644
--- a/numpy/typing/_char_codes.py
+++ b/numpy/typing/_char_codes.py
@@ -1,18 +1,14 @@
 import sys
 from typing import Any, TYPE_CHECKING
 
+from . import _HAS_TYPING_EXTENSIONS
+
 if sys.version_info >= (3, 8):
     from typing import Literal
-    HAVE_LITERAL = True
-else:
-    try:
-        from typing_extensions import Literal
-    except ImportError:
-        HAVE_LITERAL = False
-    else:
-        HAVE_LITERAL = True
-
-if TYPE_CHECKING or HAVE_LITERAL:
+elif _HAS_TYPING_EXTENSIONS:
+    from typing_extensions import Literal
+
+if TYPE_CHECKING or _HAS_TYPING_EXTENSIONS:
     _BoolCodes = Literal["?", "=?", "<?", ">?", "bool", "bool_", "bool8"]
 
     _UInt8Codes = Literal["uint8", "u1", "=u1", "<u1", ">u1"]
@@ -124,52 +120,52 @@ if TYPE_CHECKING or HAVE_LITERAL:
     ]
 
 else:
-    _BoolCodes = Any
-
-    _UInt8Codes = Any
-    _UInt16Codes = Any
-    _UInt32Codes = Any
-    _UInt64Codes = Any
-
-    _Int8Codes = Any
-    _Int16Codes = Any
-    _Int32Codes = Any
-    _Int64Codes = Any
-
-    _Float16Codes = Any
-    _Float32Codes = Any
-    _Float64Codes = Any
-
-    _Complex64Codes = Any
-    _Complex128Codes = Any
-
-    _ByteCodes = Any
-    _ShortCodes = Any
-    _IntCCodes = Any
-    _IntPCodes = Any
-    _IntCodes = Any
-    _LongLongCodes = Any
-
-    _UByteCodes = Any
-    _UShortCodes = Any
-    _UIntCCodes = Any
-    _UIntPCodes = Any
-    _UIntCodes = Any
-    _ULongLongCodes = Any
-
-    _HalfCodes = Any
-    _SingleCodes = Any
-    _DoubleCodes = Any
-    _LongDoubleCodes = Any
-
-    _CSingleCodes = Any
-    _CDoubleCodes = Any
-    _CLongDoubleCodes = Any
-
-    _StrCodes = Any
-    _BytesCodes = Any
-    _VoidCodes = Any
-    _ObjectCodes = Any
-
-    _DT64Codes = Any
-    _TD64Codes = Any
+    _BoolCodes = NotImplemented
+
+    _UInt8Codes = NotImplemented
+    _UInt16Codes = NotImplemented
+    _UInt32Codes = NotImplemented
+    _UInt64Codes = NotImplemented
+
+    _Int8Codes = NotImplemented
+    _Int16Codes = NotImplemented
+    _Int32Codes = NotImplemented
+    _Int64Codes = NotImplemented
+
+    _Float16Codes = NotImplemented
+    _Float32Codes = NotImplemented
+    _Float64Codes = NotImplemented
+
+    _Complex64Codes = NotImplemented
+    _Complex128Codes = NotImplemented
+
+    _ByteCodes = NotImplemented
+    _ShortCodes = NotImplemented
+    _IntCCodes = NotImplemented
+    _IntPCodes = NotImplemented
+    _IntCodes = NotImplemented
+    _LongLongCodes = NotImplemented
+
+    _UByteCodes = NotImplemented
+    _UShortCodes = NotImplemented
+    _UIntCCodes = NotImplemented
+    _UIntPCodes = NotImplemented
+    _UIntCodes = NotImplemented
+    _ULongLongCodes = NotImplemented
+
+    _HalfCodes = NotImplemented
+    _SingleCodes = NotImplemented
+    _DoubleCodes = NotImplemented
+    _LongDoubleCodes = NotImplemented
+
+    _CSingleCodes = NotImplemented
+    _CDoubleCodes = NotImplemented
+    _CLongDoubleCodes = NotImplemented
+
+    _StrCodes = NotImplemented
+    _BytesCodes = NotImplemented
+    _VoidCodes = NotImplemented
+    _ObjectCodes = NotImplemented
+
+    _DT64Codes = NotImplemented
+    _TD64Codes = NotImplemented
diff --git a/numpy/typing/_dtype_like.py b/numpy/typing/_dtype_like.py
index a41e2f358..405cc4a3c 100644
--- a/numpy/typing/_dtype_like.py
+++ b/numpy/typing/_dtype_like.py
@@ -2,18 +2,20 @@ import sys
 from typing import Any, List, Sequence, Tuple, Union, Type, TypeVar, TYPE_CHECKING
 
 import numpy as np
+
+from . import _HAS_TYPING_EXTENSIONS
 from ._shape import _ShapeLike
+from ._generic_alias import _DType as DType
 
 if sys.version_info >= (3, 8):
     from typing import Protocol, TypedDict
-    HAVE_PROTOCOL = True
+elif _HAS_TYPING_EXTENSIONS:
+    from typing_extensions import Protocol, TypedDict
+
+if sys.version_info >= (3, 9):
+    from types import GenericAlias
 else:
-    try:
-        from typing_extensions import Protocol, TypedDict
-    except ImportError:
-        HAVE_PROTOCOL = False
-    else:
-        HAVE_PROTOCOL = True
+    from ._generic_alias import _GenericAlias as GenericAlias
 
 from ._char_codes import (
     _BoolCodes,
@@ -58,8 +60,9 @@ from ._char_codes import (
 )
 
 _DTypeLikeNested = Any  # TODO: wait for support for recursive types
+_DType_co = TypeVar("_DType_co", covariant=True, bound=DType[Any])
 
-if TYPE_CHECKING or HAVE_PROTOCOL:
+if TYPE_CHECKING or _HAS_TYPING_EXTENSIONS:
     # Mandatory keys
     class _DTypeDictBase(TypedDict):
         names: Sequence[str]
@@ -72,16 +75,16 @@ if TYPE_CHECKING or HAVE_PROTOCOL:
         itemsize: int
         aligned: bool
 
-    _DType_co = TypeVar("_DType_co", covariant=True, bound=np.dtype)
-
     # A protocol for anything with the dtype attribute
     class _SupportsDType(Protocol[_DType_co]):
         @property
         def dtype(self) -> _DType_co: ...
 
 else:
-    _DTypeDict = Any
-    _SupportsDType = Any
+    _DTypeDict = NotImplemented
+
+    class _SupportsDType: ...
+    _SupportsDType = GenericAlias(_SupportsDType, _DType_co)
 
 
 # Would create a dtype[np.void]
@@ -106,13 +109,13 @@ _VoidDTypeLike = Union[
 # Anything that can be coerced into numpy.dtype.
 # Reference: https://docs.scipy.org/doc/numpy/reference/arrays.dtypes.html
 DTypeLike = Union[
-    np.dtype,
+    DType[Any],
     # default data type (float64)
     None,
     # array-scalar types and generic types
-    type,  # TODO: enumerate these when we add type hints for numpy scalars
+    Type[Any],  # TODO: enumerate these when we add type hints for numpy scalars
     # anything with a dtype attribute
-    "_SupportsDType[np.dtype[Any]]",
+    _SupportsDType[DType[Any]],
     # character codes, type strings or comma-separated fields, e.g., 'float64'
     str,
     _VoidDTypeLike,
@@ -130,14 +133,14 @@ DTypeLike = Union[
 _DTypeLikeBool = Union[
     Type[bool],
     Type[np.bool_],
-    "np.dtype[np.bool_]",
-    "_SupportsDType[np.dtype[np.bool_]]",
+    DType[np.bool_],
+    _SupportsDType[DType[np.bool_]],
     _BoolCodes,
 ]
 _DTypeLikeUInt = Union[
     Type[np.unsignedinteger],
-    "np.dtype[np.unsignedinteger]",
-    "_SupportsDType[np.dtype[np.unsignedinteger]]",
+    DType[np.unsignedinteger],
+    _SupportsDType[DType[np.unsignedinteger]],
     _UInt8Codes,
     _UInt16Codes,
     _UInt32Codes,
@@ -152,8 +155,8 @@ _DTypeLikeUInt = Union[
 _DTypeLikeInt = Union[
     Type[int],
     Type[np.signedinteger],
-    "np.dtype[np.signedinteger]",
-    "_SupportsDType[np.dtype[np.signedinteger]]",
+    DType[np.signedinteger],
+    _SupportsDType[DType[np.signedinteger]],
     _Int8Codes,
     _Int16Codes,
     _Int32Codes,
@@ -168,8 +171,8 @@ _DTypeLikeInt = Union[
 _DTypeLikeFloat = Union[
     Type[float],
     Type[np.floating],
-    "np.dtype[np.floating]",
-    "_SupportsDType[np.dtype[np.floating]]",
+    DType[np.floating],
+    _SupportsDType[DType[np.floating]],
     _Float16Codes,
     _Float32Codes,
     _Float64Codes,
@@ -181,8 +184,8 @@ _DTypeLikeFloat = Union[
 _DTypeLikeComplex = Union[
     Type[complex],
     Type[np.complexfloating],
-    "np.dtype[np.complexfloating]",
-    "_SupportsDType[np.dtype[np.complexfloating]]",
+    DType[np.complexfloating],
+    _SupportsDType[DType[np.complexfloating]],
     _Complex64Codes,
     _Complex128Codes,
     _CSingleCodes,
@@ -191,41 +194,41 @@ _DTypeLikeComplex = Union[
 ]
 _DTypeLikeDT64 = Union[
     Type[np.timedelta64],
-    "np.dtype[np.timedelta64]",
-    "_SupportsDType[np.dtype[np.timedelta64]]",
+    DType[np.timedelta64],
+    _SupportsDType[DType[np.timedelta64]],
     _TD64Codes,
 ]
 _DTypeLikeTD64 = Union[
     Type[np.datetime64],
-    "np.dtype[np.datetime64]",
-    "_SupportsDType[np.dtype[np.datetime64]]",
+    DType[np.datetime64],
+    _SupportsDType[DType[np.datetime64]],
     _DT64Codes,
 ]
 _DTypeLikeStr = Union[
     Type[str],
     Type[np.str_],
-    "np.dtype[np.str_]",
-    "_SupportsDType[np.dtype[np.str_]]",
+    DType[np.str_],
+    _SupportsDType[DType[np.str_]],
     _StrCodes,
 ]
 _DTypeLikeBytes = Union[
     Type[bytes],
     Type[np.bytes_],
-    "np.dtype[np.bytes_]",
-    "_SupportsDType[np.dtype[np.bytes_]]",
+    DType[np.bytes_],
+    _SupportsDType[DType[np.bytes_]],
     _BytesCodes,
 ]
 _DTypeLikeVoid = Union[
     Type[np.void],
-    "np.dtype[np.void]",
-    "_SupportsDType[np.dtype[np.void]]",
+    DType[np.void],
+    _SupportsDType[DType[np.void]],
     _VoidCodes,
     _VoidDTypeLike,
 ]
 _DTypeLikeObject = Union[
     type,
-    "np.dtype[np.object_]",
-    "_SupportsDType[np.dtype[np.object_]]",
+    DType[np.object_],
+    _SupportsDType[DType[np.object_]],
     _ObjectCodes,
 ]
 
diff --git a/numpy/typing/_generic_alias.py b/numpy/typing/_generic_alias.py
index 68523827a..0d30f54ca 100644
--- a/numpy/typing/_generic_alias.py
+++ b/numpy/typing/_generic_alias.py
@@ -199,6 +199,7 @@ else:
 ScalarType = TypeVar("ScalarType", bound=np.generic, covariant=True)
 
 if TYPE_CHECKING:
+    _DType = np.dtype[ScalarType]
     NDArray = np.ndarray[Any, np.dtype[ScalarType]]
 elif sys.version_info >= (3, 9):
     _DType = types.GenericAlias(np.dtype, (ScalarType,))
diff --git a/numpy/typing/_shape.py b/numpy/typing/_shape.py
index b720c3ffc..0742be8a9 100644
--- a/numpy/typing/_shape.py
+++ b/numpy/typing/_shape.py
@@ -1,13 +1,14 @@
 import sys
 from typing import Sequence, Tuple, Union
 
+from . import _HAS_TYPING_EXTENSIONS
+
 if sys.version_info >= (3, 8):
     from typing import SupportsIndex
+elif _HAS_TYPING_EXTENSIONS:
+    from typing_extensions import SupportsIndex
 else:
-    try:
-        from typing_extensions import SupportsIndex
-    except ImportError:
-        SupportsIndex = NotImplemented
+    SupportsIndex = NotImplemented
 
 _Shape = Tuple[int, ...]
 
diff --git a/numpy/typing/_ufunc.pyi b/numpy/typing/_ufunc.pyi
index b3b9fa95e..f4fead504 100644
--- a/numpy/typing/_ufunc.pyi
+++ b/numpy/typing/_ufunc.pyi
@@ -11,11 +11,9 @@ from typing import (
     Any,
     Generic,
     List,
-    Optional,
     overload,
     Tuple,
     TypeVar,
-    Union,
 )
 
 from numpy import ufunc, _Casting, _OrderKACF
@@ -82,26 +80,26 @@ class _UFunc_Nin1_Nout1(ufunc, Generic[_NameType, _NTypes, _IDType]):
         __x1: _ScalarLike_co,
         out: None = ...,
         *,
-        where: Optional[_ArrayLikeBool_co] = ...,
+        where: None | _ArrayLikeBool_co = ...,
         casting: _Casting = ...,
         order: _OrderKACF = ...,
         dtype: DTypeLike = ...,
         subok: bool = ...,
-        signature: Union[str, _2Tuple[Optional[str]]] = ...,
+        signature: str | _2Tuple[None | str] = ...,
         extobj: List[Any] = ...,
     ) -> Any: ...
     @overload
     def __call__(
         self,
         __x1: ArrayLike,
-        out: Union[None, NDArray[Any], Tuple[NDArray[Any]]] = ...,
+        out: None | NDArray[Any] | Tuple[NDArray[Any]] = ...,
         *,
-        where: Optional[_ArrayLikeBool_co] = ...,
+        where: None | _ArrayLikeBool_co = ...,
         casting: _Casting = ...,
         order: _OrderKACF = ...,
         dtype: DTypeLike = ...,
         subok: bool = ...,
-        signature: Union[str, _2Tuple[Optional[str]]] = ...,
+        signature: str | _2Tuple[None | str] = ...,
         extobj: List[Any] = ...,
     ) -> NDArray[Any]: ...
 
@@ -134,12 +132,12 @@ class _UFunc_Nin2_Nout1(ufunc, Generic[_NameType, _NTypes, _IDType]):
         __x2: _ScalarLike_co,
         out: None = ...,
         *,
-        where: Optional[_ArrayLikeBool_co] = ...,
+        where: None | _ArrayLikeBool_co = ...,
         casting: _Casting = ...,
         order: _OrderKACF = ...,
         dtype: DTypeLike = ...,
         subok: bool = ...,
-        signature: Union[str, _3Tuple[Optional[str]]] = ...,
+        signature: str | _3Tuple[None | str] = ...,
         extobj: List[Any] = ...,
     ) -> Any: ...
     @overload
@@ -147,14 +145,14 @@ class _UFunc_Nin2_Nout1(ufunc, Generic[_NameType, _NTypes, _IDType]):
         self,
         __x1: ArrayLike,
         __x2: ArrayLike,
-        out: Union[None, NDArray[Any], Tuple[NDArray[Any]]] = ...,
+        out: None | NDArray[Any] | Tuple[NDArray[Any]] = ...,
         *,
-        where: Optional[_ArrayLikeBool_co] = ...,
+        where: None | _ArrayLikeBool_co = ...,
         casting: _Casting = ...,
         order: _OrderKACF = ...,
         dtype: DTypeLike = ...,
         subok: bool = ...,
-        signature: Union[str, _3Tuple[Optional[str]]] = ...,
+        signature: str | _3Tuple[None | str] = ...,
         extobj: List[Any] = ...,
     ) -> NDArray[Any]: ...
 
@@ -168,9 +166,9 @@ class _UFunc_Nin2_Nout1(ufunc, Generic[_NameType, _NTypes, _IDType]):
     def reduce(
         self,
         array: ArrayLike,
-        axis: Optional[_ShapeLike] = ...,
+        axis: None | _ShapeLike = ...,
         dtype: DTypeLike = ...,
-        out: Optional[NDArray[Any]] = ...,
+        out: None | NDArray[Any] = ...,
         keepdims: bool = ...,
         initial: Any = ...,
         where: _ArrayLikeBool_co = ...,
@@ -181,7 +179,7 @@ class _UFunc_Nin2_Nout1(ufunc, Generic[_NameType, _NTypes, _IDType]):
         array: ArrayLike,
         axis: SupportsIndex = ...,
         dtype: DTypeLike = ...,
-        out: Optional[NDArray[Any]] = ...,
+        out: None | NDArray[Any] = ...,
     ) -> NDArray[Any]: ...
 
     def reduceat(
@@ -190,7 +188,7 @@ class _UFunc_Nin2_Nout1(ufunc, Generic[_NameType, _NTypes, _IDType]):
         indices: _ArrayLikeInt_co,
         axis: SupportsIndex = ...,
         dtype: DTypeLike = ...,
-        out: Optional[NDArray[Any]] = ...,
+        out: None | NDArray[Any] = ...,
     ) -> NDArray[Any]: ...
 
     # Expand `**kwargs` into explicit keyword-only arguments
@@ -201,12 +199,12 @@ class _UFunc_Nin2_Nout1(ufunc, Generic[_NameType, _NTypes, _IDType]):
         __B: _ScalarLike_co,
         *,
         out: None = ...,
-        where: Optional[_ArrayLikeBool_co] = ...,
+        where: None | _ArrayLikeBool_co = ...,
         casting: _Casting = ...,
         order: _OrderKACF = ...,
         dtype: DTypeLike = ...,
         subok: bool = ...,
-        signature: Union[str, _3Tuple[Optional[str]]] = ...,
+        signature: str | _3Tuple[None | str] = ...,
         extobj: List[Any] = ...,
     ) -> Any: ...
     @overload
@@ -215,13 +213,13 @@ class _UFunc_Nin2_Nout1(ufunc, Generic[_NameType, _NTypes, _IDType]):
         __A: ArrayLike,
         __B: ArrayLike,
         *,
-        out: Union[None, NDArray[Any], Tuple[NDArray[Any]]] = ...,
-        where: Optional[_ArrayLikeBool_co] = ...,
+        out: None | NDArray[Any] | Tuple[NDArray[Any]] = ...,
+        where: None | _ArrayLikeBool_co = ...,
         casting: _Casting = ...,
         order: _OrderKACF = ...,
         dtype: DTypeLike = ...,
         subok: bool = ...,
-        signature: Union[str, _3Tuple[Optional[str]]] = ...,
+        signature: str | _3Tuple[None | str] = ...,
         extobj: List[Any] = ...,
     ) -> NDArray[Any]: ...
 
@@ -258,28 +256,28 @@ class _UFunc_Nin1_Nout2(ufunc, Generic[_NameType, _NTypes, _IDType]):
         __out1: None = ...,
         __out2: None = ...,
         *,
-        where: Optional[_ArrayLikeBool_co] = ...,
+        where: None | _ArrayLikeBool_co = ...,
         casting: _Casting = ...,
         order: _OrderKACF = ...,
         dtype: DTypeLike = ...,
         subok: bool = ...,
-        signature: Union[str, _3Tuple[Optional[str]]] = ...,
+        signature: str | _3Tuple[None | str] = ...,
         extobj: List[Any] = ...,
     ) -> _2Tuple[Any]: ...
     @overload
     def __call__(
         self,
         __x1: ArrayLike,
-        __out1: Optional[NDArray[Any]] = ...,
-        __out2: Optional[NDArray[Any]] = ...,
+        __out1: None | NDArray[Any] = ...,
+        __out2: None | NDArray[Any] = ...,
         *,
         out: _2Tuple[NDArray[Any]] = ...,
-        where: Optional[_ArrayLikeBool_co] = ...,
+        where: None | _ArrayLikeBool_co = ...,
         casting: _Casting = ...,
         order: _OrderKACF = ...,
         dtype: DTypeLike = ...,
         subok: bool = ...,
-        signature: Union[str, _3Tuple[Optional[str]]] = ...,
+        signature: str | _3Tuple[None | str] = ...,
         extobj: List[Any] = ...,
     ) -> _2Tuple[NDArray[Any]]: ...
 
@@ -317,12 +315,12 @@ class _UFunc_Nin2_Nout2(ufunc, Generic[_NameType, _NTypes, _IDType]):
         __out1: None = ...,
         __out2: None = ...,
         *,
-        where: Optional[_ArrayLikeBool_co] = ...,
+        where: None | _ArrayLikeBool_co = ...,
         casting: _Casting = ...,
         order: _OrderKACF = ...,
         dtype: DTypeLike = ...,
         subok: bool = ...,
-        signature: Union[str, _4Tuple[Optional[str]]] = ...,
+        signature: str | _4Tuple[None | str] = ...,
         extobj: List[Any] = ...,
     ) -> _2Tuple[Any]: ...
     @overload
@@ -330,16 +328,16 @@ class _UFunc_Nin2_Nout2(ufunc, Generic[_NameType, _NTypes, _IDType]):
         self,
         __x1: ArrayLike,
         __x2: ArrayLike,
-        __out1: Optional[NDArray[Any]] = ...,
-        __out2: Optional[NDArray[Any]] = ...,
+        __out1: None | NDArray[Any] = ...,
+        __out2: None | NDArray[Any] = ...,
         *,
         out: _2Tuple[NDArray[Any]] = ...,
-        where: Optional[_ArrayLikeBool_co] = ...,
+        where: None | _ArrayLikeBool_co = ...,
         casting: _Casting = ...,
         order: _OrderKACF = ...,
         dtype: DTypeLike = ...,
         subok: bool = ...,
-        signature: Union[str, _4Tuple[Optional[str]]] = ...,
+        signature: str | _4Tuple[None | str] = ...,
         extobj: List[Any] = ...,
     ) -> _2Tuple[NDArray[Any]]: ...
 
@@ -384,7 +382,7 @@ class _GUFunc_Nin2_Nout1(ufunc, Generic[_NameType, _NTypes, _IDType]):
         order: _OrderKACF = ...,
         dtype: DTypeLike = ...,
         subok: bool = ...,
-        signature: Union[str, _3Tuple[Optional[str]]] = ...,
+        signature: str | _3Tuple[None | str] = ...,
         extobj: List[Any] = ...,
         axes: List[_2Tuple[SupportsIndex]] = ...,
     ) -> Any: ...
@@ -393,13 +391,13 @@ class _GUFunc_Nin2_Nout1(ufunc, Generic[_NameType, _NTypes, _IDType]):
         self,
         __x1: ArrayLike,
         __x2: ArrayLike,
-        out: Union[NDArray[Any], Tuple[NDArray[Any]]],
+        out: NDArray[Any] | Tuple[NDArray[Any]],
         *,
         casting: _Casting = ...,
         order: _OrderKACF = ...,
         dtype: DTypeLike = ...,
         subok: bool = ...,
-        signature: Union[str, _3Tuple[Optional[str]]] = ...,
+        signature: str | _3Tuple[None | str] = ...,
         extobj: List[Any] = ...,
         axes: List[_2Tuple[SupportsIndex]] = ...,
     ) -> NDArray[Any]: ...
diff --git a/numpy/typing/mypy_plugin.py b/numpy/typing/mypy_plugin.py
index 901bf4fb1..100e0d957 100644
--- a/numpy/typing/mypy_plugin.py
+++ b/numpy/typing/mypy_plugin.py
@@ -14,7 +14,7 @@ try:
     from mypy.build import PRI_MED
 
     _HookFunc = t.Callable[[AnalyzeTypeContext], Type]
-    MYPY_EX: t.Optional[ModuleNotFoundError] = None
+    MYPY_EX: None | ModuleNotFoundError = None
 except ModuleNotFoundError as ex:
     MYPY_EX = ex
 
@@ -90,7 +90,7 @@ if t.TYPE_CHECKING or MYPY_EX is None:
     class _NumpyPlugin(Plugin):
         """A plugin for assigning platform-specific `numpy.number` precisions."""
 
-        def get_type_analyze_hook(self, fullname: str) -> t.Optional[_HookFunc]:
+        def get_type_analyze_hook(self, fullname: str) -> None | _HookFunc:
             """Set the precision of platform-specific `numpy.number` subclasses.
 
             For example: `numpy.int_`, `numpy.longlong` and `numpy.longdouble`.