From eb00e9070165ebee26c05b239f06ed7c03314e49 Mon Sep 17 00:00:00 2001
From: Elvis Pranskevichus <elvis@edgedb.com>
Date: Tue, 13 Sep 2022 16:36:22 -0700
Subject: [PATCH] Add Py_GenericAlias

Useful for extensions implementing generic container types, like
`immutables` (see MagicStack/immutables#89).

Co-Authored-By: ToBeReplaced <ToBeReplaced@gmail.com>
---
 pythoncapi_compat.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/pythoncapi_compat.h b/pythoncapi_compat.h
index d422996..05a58f7 100644
--- a/pythoncapi_compat.h
+++ b/pythoncapi_compat.h
@@ -428,6 +428,15 @@ _Py_IS_TYPE(PyObject *ob, PyTypeObject *type) {
 #define Py_IS_TYPE(ob, type) _Py_IS_TYPE(_PyObject_CAST(ob), type)
 #endif
 
+// bpo-39481 added Py_GenericAlias to Python 3.9.0a6.
+#if PY_VERSION_HEX < 0x030900A6 && !defined(Py_GenericAlias)
+PYCAPI_COMPAT_STATIC_INLINE(PyObject *)
+Py_GenericAlias(PyObject *type, PyObject *item)
+{
+    Py_INCREF(type);
+    return type;
+}
+#endif
 
 // bpo-46906 added PyFloat_Pack2() and PyFloat_Unpack2() to Python 3.11a7.
 // bpo-11734 added _PyFloat_Pack2() and _PyFloat_Unpack2() to Python 3.6.0b1.