From ad366d0422225146f24881abeeef7f972f81edcd Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Tue, 18 Feb 2025 11:00:03 +0100
Subject: [PATCH] Don't redefine _Py_NULL macro if already defined

Original mypy fix by Michael R. Crusoe.
---
 pythoncapi_compat.h | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/pythoncapi_compat.h b/pythoncapi_compat.h
index 4d28846..836df7e 100644
--- a/pythoncapi_compat.h
+++ b/pythoncapi_compat.h
@@ -37,11 +37,13 @@ extern "C" {
 // Static inline functions should use _Py_NULL rather than using directly NULL
 // to prevent C++ compiler warnings. On C23 and newer and on C++11 and newer,
 // _Py_NULL is defined as nullptr.
-#if (defined (__STDC_VERSION__) && __STDC_VERSION__ > 201710L) \
-        || (defined(__cplusplus) && __cplusplus >= 201103)
-#  define _Py_NULL nullptr
-#else
-#  define _Py_NULL NULL
+#ifndef _Py_NULL
+#  if (defined (__STDC_VERSION__) && __STDC_VERSION__ > 201710L) \
+          || (defined(__cplusplus) && __cplusplus >= 201103)
+#    define _Py_NULL nullptr
+#  else
+#    define _Py_NULL NULL
+#  endif
 #endif
 
 // Cast argument to PyObject* type.