Apply suggestions from code review

Co-authored-by: Victor Stinner <vstinner@python.org>

Author: skirpichev

Lib/test/test_struct.py

@@ -594,7 +594,7 @@ def test_Struct_reinitialization(self):
 
     def check_sizeof(self, format_str, number_of_codes):
         # The size of 'PyStructObject'
-        totalsize = support.calcobjsize('2n3P1?')
+        totalsize = support.calcobjsize('2n3P?')
         # The size taken up by the 'formatcode' dynamic array
         totalsize += struct.calcsize('P3n0P') * (number_of_codes + 1)
         support.check_sizeof(self, struct.Struct(format_str), totalsize)

Misc/NEWS.d/next/Library/2026-01-10-16-23-21.gh-issue-143715.HZrfSA.rst

@@ -1,3 +1,3 @@
-Calling the ``Struct.__new__()`` without required argument now is deprecated.
+:mod:`struct`: Calling the ``Struct.__new__()`` without required argument now is deprecated.
 Calling :meth:`~object.__init__` method on initialized :class:`~struct.Struct`
 objects is deprecated.  Patch by Sergey B Kirpichev.

Modules/_struct.c

@@ -1809,7 +1809,7 @@ s_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
     if (self == NULL) {
         return NULL;
     }
-    self->s_format = Py_NewRef(Py_None);
+    self->s_format = Py_None;
     self->s_codes = NULL;
     self->s_size = -1;
     self->s_len = -1;