Define PY_SSIZE_T_CLEAN macro

before #include "Python.h" as recommended in Python 3.7 and later.

Issue #2277

CHANGES.current

@@ -7,6 +7,17 @@ the issue number to the end of the URL: https://github.com/swig/swig/issues/
 Version 4.1.0 (in progress)
 ===========================
 
+2022-05-27: xypron
+            [Python] #2277 Define PY_SSIZE_T_CLEAN macro before #include "Python.h" as
+            recommended in Python 3.7 and later.
+
+            To avoid this macro definition, add the following to your interface file so
+            that SWIG_NO_PY_SSIZE_T_CLEAN is defined at the beginning of the C++ wrappers:
+
+              %begin %{
+              #define SWIG_NO_PY_SSIZE_T_CLEAN
+              %}
+
 2022-05-07: KrisThielemans
             [Python] Fix "too many initializers for 'PyHeapTypeObject'" errors
             using PyPy 3.8 and later.

Lib/python/embed.i

@@ -29,7 +29,7 @@ As far as I know, this module is C++ safe.
 #endif
 
 %wrapper %{
-#ifndef PY_SSIZE_T_CLEAN
+#ifndef SWIG_NO_PY_SSIZE_T_CLEAN
 #define PY_SSIZE_T_CLEAN
 #endif
 #include <Python.h>

Lib/python/pyruntime.swg

@@ -11,7 +11,7 @@
 # include <corecrt.h>
 #endif
 
-#ifndef PY_SSIZE_T_CLEAN
+#ifndef SWIG_NO_PY_SSIZE_T_CLEAN
 #define PY_SSIZE_T_CLEAN
 #endif
 #if defined(_DEBUG) && defined(SWIG_PYTHON_INTERPRETER_NO_DEBUG)