From 103474c9f82c636b361bf3c10de892f685f14abd Mon Sep 17 00:00:00 2001
From: ToBeReplaced <ToBeReplaced@gmail.com>
Date: Tue, 5 Jul 2022 12:27:15 +0800
Subject: [PATCH] Add PEP 585 (__class_getitem__ -> GenericAlias) support

---
 immutables/_map.c              | 11 ++---------
 immutables/pythoncapi_compat.h | 11 +++++++++++
 2 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/immutables/_map.c b/immutables/_map.c
index 7e510fd1..2dea8352 100644
--- a/immutables/_map.c
+++ b/immutables/_map.c
@@ -3359,13 +3359,6 @@ map_reduce(MapObject *self)
     return tup;
 }
 
-static PyObject *
-map_py_class_getitem(PyObject *type, PyObject *item)
-{
-    Py_INCREF(type);
-    return type;
-}
-
 static PyMethodDef Map_methods[] = {
     {"set", (PyCFunction)map_py_set, METH_VARARGS, NULL},
     {"get", (PyCFunction)map_py_get, METH_VARARGS, NULL},
@@ -3379,9 +3372,9 @@ static PyMethodDef Map_methods[] = {
     {"__dump__", (PyCFunction)map_py_dump, METH_NOARGS, NULL},
     {
         "__class_getitem__",
-        (PyCFunction)map_py_class_getitem,
+        Py_GenericAlias,
         METH_O|METH_CLASS,
-        NULL
+        "See PEP 585"
     },
     {NULL, NULL}
 };
diff --git a/immutables/pythoncapi_compat.h b/immutables/pythoncapi_compat.h
index 2837467e..890dfece 100644
--- a/immutables/pythoncapi_compat.h
+++ b/immutables/pythoncapi_compat.h
@@ -406,6 +406,17 @@ PyFloat_Unpack2(const char *p, int le)
 #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_Pack4(), PyFloat_Pack8(), PyFloat_Unpack4() and
 // PyFloat_Unpack8() to Python 3.11a7.
 // Python 3.11a2 moved _PyFloat_Pack4(), _PyFloat_Pack8(), _PyFloat_Unpack4()