From 8767ce92d24d3687405848442e6c67cf0af1c657 Mon Sep 17 00:00:00 2001
From: Andy Lester <andy@petdance.com>
Date: Fri, 6 Mar 2020 02:03:58 -0600
Subject: [PATCH] bpo-39573: Make Py_IS_TYPE() take constant parameters
 (GH-18799)

Add _PyObject_CAST_CONST() macro: cast a pointer to (const PyObject *).
---
 Include/object.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/Include/object.h b/Include/object.h
index 3d0da52c2b6..6b6c66a52a6 100644
--- a/Include/object.h
+++ b/Include/object.h
@@ -110,6 +110,7 @@ typedef struct _object {
 
 /* Cast argument to PyObject* type. */
 #define _PyObject_CAST(op) ((PyObject*)(op))
+#define _PyObject_CAST_CONST(op) ((const PyObject*)(op))
 
 typedef struct {
     PyObject ob_base;
@@ -123,10 +124,10 @@ typedef struct {
 #define Py_TYPE(ob)             (_PyObject_CAST(ob)->ob_type)
 #define Py_SIZE(ob)             (_PyVarObject_CAST(ob)->ob_size)
 
-static inline int _Py_IS_TYPE(PyObject *ob, PyTypeObject *type) {
+static inline int _Py_IS_TYPE(const PyObject *ob, const PyTypeObject *type) {
     return ob->ob_type == type;
 }
-#define Py_IS_TYPE(ob, type) _Py_IS_TYPE(_PyObject_CAST(ob), type)
+#define Py_IS_TYPE(ob, type) _Py_IS_TYPE(_PyObject_CAST_CONST(ob), type)
 
 static inline void _Py_SET_REFCNT(PyObject *ob, Py_ssize_t refcnt) {
     ob->ob_refcnt = refcnt;