refactor: add shim for Py_SET_SIZE

Author: Xmader

include/pyshim.hh

@@ -107,4 +107,15 @@ inline void PyErr_SetKeyError(PyObject *key) {
 #endif
 }
 
+/**
+ * @brief Shim for `Py_SET_SIZE`.
+ *        `Py_SET_SIZE` is not available in Python < 3.9
+ */
+#ifndef Py_SET_SIZE
+static inline void _Py_SET_SIZE(PyVarObject *ob, Py_ssize_t size) {
+  ob->ob_size = size;
+}
+#define Py_SET_SIZE(ob, size) _Py_SET_SIZE((PyVarObject *)(ob), size)
+#endif
+
 #endif // #ifndef PythonMonkey_py_version_shim_

src/IntType.cc

@@ -44,11 +44,7 @@ static inline void PythonLong_SetSign(PyLongObject *op, int sign) {
 #else // Python version is less than 3.12
   // see https://github.com/python/cpython/blob/v3.9.16/Objects/longobject.c#L956
   Py_ssize_t pyDigitCount = Py_SIZE(op);
-  #if PY_VERSION_HEX >= 0x03090000
   Py_SET_SIZE(op, sign * std::abs(pyDigitCount));
-  #else
-  ((PyVarObject *)op)->ob_size = sign * std::abs(pyDigitCount); // Py_SET_SIZE is not available in Python < 3.9
-  #endif
 #endif
 }