TYP: Add annotations for the py3.12 buffer protocol

numpy/__init__.pyi

@@ -1,4 +1,5 @@
 import builtins
+import sys
 import os
 import mmap
 import ctypes as ct
@@ -1440,17 +1441,18 @@ _ShapeType = TypeVar("_ShapeType", bound=Any)
 _ShapeType2 = TypeVar("_ShapeType2", bound=Any)
 _NumberType = TypeVar("_NumberType", bound=number[Any])
 
-# There is currently no exhaustive way to type the buffer protocol,
-# as it is implemented exclusively in the C API (python/typing#593)
-_SupportsBuffer = Union[
-    bytes,
-    bytearray,
-    memoryview,
-    _array.array[Any],
-    mmap.mmap,
-    NDArray[Any],
-    generic,
-]
+if sys.version_info >= (3, 12):
+    from collections.abc import Buffer as _SupportsBuffer
+else:
+    _SupportsBuffer = (
+        bytes
+        | bytearray
+        | memoryview
+        | _array.array[Any]
+        | mmap.mmap
+        | NDArray[Any]
+        | generic
+    )
 
 _T = TypeVar("_T")
 _T_co = TypeVar("_T_co", covariant=True)
@@ -1513,6 +1515,9 @@ class ndarray(_ArrayOrScalarCommon, Generic[_ShapeType, _DType_co]):
         order: _OrderKACF = ...,
     ) -> _ArraySelf: ...
 
+    if sys.version_info >= (3, 12):
+        def __buffer__(self, flags: int, /) -> memoryview: ...
+
     def __class_getitem__(self, item: Any) -> GenericAlias: ...
 
     @overload
@@ -2570,6 +2575,9 @@ class generic(_ArrayOrScalarCommon):
     @property
     def flat(self: _ScalarType) -> flatiter[ndarray[Any, _dtype[_ScalarType]]]: ...
 
+    if sys.version_info >= (3, 12):
+        def __buffer__(self, flags: int, /) -> memoryview: ...
+
     @overload
     def astype(
         self,
@@ -2772,6 +2780,9 @@ class object_(generic):
     def __float__(self) -> float: ...
     def __complex__(self) -> complex: ...
 
+    if sys.version_info >= (3, 12):
+        def __release_buffer__(self, buffer: memoryview, /) -> None: ...
+
 # The `datetime64` constructors requires an object with the three attributes below,
 # and thus supports datetime duck typing
 class _DatetimeScalar(Protocol):

numpy/_typing/_array_like.py

@@ -1,7 +1,9 @@
 from __future__ import annotations
 
+import sys
 from collections.abc import Collection, Callable, Sequence
 from typing import Any, Protocol, Union, TypeVar, runtime_checkable
+
 from numpy import (
     ndarray,
     dtype,
@@ -76,17 +78,18 @@ def __array_function__(
     _NestedSequence[_T],
 ]
 
-# TODO: support buffer protocols once
-#
-# https://bugs.python.org/issue27501
-#
-# is resolved. See also the mypy issue:
-#
-# https://github.com/python/typing/issues/593
-ArrayLike = _DualArrayLike[
-    dtype[Any],
-    Union[bool, int, float, complex, str, bytes],
-]
+if sys.version_info >= (3, 12):
+    from collections.abc import Buffer
+
+    ArrayLike = Buffer | _DualArrayLike[
+        dtype[Any],
+        Union[bool, int, float, complex, str, bytes],
+    ]
+else:
+    ArrayLike = _DualArrayLike[
+        dtype[Any],
+        Union[bool, int, float, complex, str, bytes],
+    ]
 
 # `ArrayLike<X>_co`: array-like objects that can be coerced into `X`
 # given the casting rules `same_kind`

numpy/array_api/_typing.py

@@ -17,6 +17,8 @@
     "PyCapsule",
 ]
 
+import sys
+
 from typing import (
     Any,
     Literal,
@@ -63,8 +65,11 @@ def __len__(self, /) -> int: ...
     float64,
 ]]
 
+if sys.version_info >= (3, 12):
+    from collections.abc import Buffer as SupportsBufferProtocol
+else:
+    SupportsBufferProtocol = Any
 
-SupportsBufferProtocol = Any
 PyCapsule = Any
 
 class SupportsDLPack(Protocol):

numpy/typing/tests/data/reveal/array_constructors.pyi

@@ -211,3 +211,11 @@ assert_type(np.stack([A, A], out=B), SubClass[np.float64])
 
 assert_type(np.block([[A, A], [A, A]]), npt.NDArray[Any])
 assert_type(np.block(C), npt.NDArray[Any])
+
+if sys.version_info >= (3, 12):
+    from collections.abc import Buffer
+
+    def create_array(obj: npt.ArrayLike) -> npt.NDArray[Any]: ...
+
+    buffer: Buffer
+    assert_type(create_array(buffer), npt.NDArray[Any])