bpo-39481: Implementation for PEP 585 (#18239)
This implements things like `list[int]`,
which returns an object of type `types.GenericAlias`.
This object mostly acts as a proxy for `list`,
but has attributes `__origin__` and `__args__`
that allow recovering the parts (with values `list` and `(int,)`.
There is also an approximate notion of type variables;
e.g. `list[T]` has a `__parameters__` attribute equal to `(T,)`.
Type variables are objects of type `typing.TypeVar`.
diff --git a/Objects/descrobject.c b/Objects/descrobject.c
index cb7572b..5fab222 100644
--- a/Objects/descrobject.c
+++ b/Objects/descrobject.c
@@ -1092,6 +1092,8 @@
PyDoc_STR("D.items() -> list of D's (key, value) pairs, as 2-tuples")},
{"copy", (PyCFunction)mappingproxy_copy, METH_NOARGS,
PyDoc_STR("D.copy() -> a shallow copy of D")},
+ {"__class_getitem__", (PyCFunction)Py_GenericAlias, METH_O|METH_CLASS,
+ PyDoc_STR("See PEP 585")},
{0}
};