gh-126012: Add `__class_getitem__` to `memoryview` (#126013)

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>
Co-authored-by: Peter Bierma <zintensitydev@gmail.com>

Doc/library/stdtypes.rst

@@ -3889,6 +3889,9 @@ copying.
    .. versionchanged:: 3.5
       memoryviews can now be indexed with tuple of integers.
 
+   .. versionchanged:: next
+      memoryview is now a :term:`generic type`.
+
    :class:`memoryview` has several methods:
 
    .. method:: __eq__(exporter)

Doc/whatsnew/3.14.rst

@@ -194,6 +194,10 @@ Other language changes
   :mod:`copyable <copy>`.
   (Contributed by Serhiy Storchaka in :gh:`125767`.)
 
+* The :class:`memoryview` type now supports subscription,
+  making it a :term:`generic type`.
+  (Contributed by Brian Schubert in :gh:`126012`.)
+
 
 New modules
 ===========

Lib/test/test_genericalias.py

@@ -100,7 +100,7 @@ _UNPACKED_TUPLES = [
 
 class BaseTest(unittest.TestCase):
     """Test basics."""
-    generic_types = [type, tuple, list, dict, set, frozenset, enumerate,
+    generic_types = [type, tuple, list, dict, set, frozenset, enumerate, memoryview,
                      defaultdict, deque,
                      SequenceMatcher,
                      dircmp,

Misc/NEWS.d/next/Core and Builtins/2024-10-26-13-32-48.gh-issue-126012.2KalhG.rst

@@ -0,0 +1,2 @@
+The :class:`memoryview` type now supports subscription, making it a
+:term:`generic type`.

Objects/memoryobject.c

@@ -3286,6 +3286,7 @@ static PyMethodDef memory_methods[] = {
     MEMORYVIEW__FROM_FLAGS_METHODDEF
     {"__enter__",   memory_enter, METH_NOARGS, NULL},
     {"__exit__",    memory_exit, METH_VARARGS, memory_exit_doc},
+    {"__class_getitem__", Py_GenericAlias, METH_O|METH_CLASS, PyDoc_STR("See PEP 585")},
     {NULL,          NULL}
 };