gh-115231: fill __module__ for built-in staticmethods

Lib/test/test_funcattrs.py

@@ -453,6 +453,29 @@ class BuiltinFunctionPropertiesTest(unittest.TestCase):
     # XXX Not sure where this should really go since I can't find a
     # test module specifically for builtin_function_or_method.
 
+    def test_builtin__module__(self):
+        import decimal
+        import math
+
+        # builtin function:
+        self.assertEqual(len.__module__, 'builtins')
+        self.assertEqual(math.sin.__module__, 'math')
+
+        # instance method:
+        self.assertRaises(AttributeError, getattr, int.to_bytes, '__module__')
+        self.assertRaises(AttributeError, getattr, decimal.Decimal.exp, '__module__')
+        self.assertEqual(int.to_bytes.__objclass__.__module__, 'builtins')
+        self.assertEqual(decimal.Decimal.exp.__objclass__.__module__, 'decimal')
+
+        # builtin classmethod:
+        self.assertEqual(int.from_bytes.__module__, 'builtins')
+        self.assertEqual(int.from_bytes.__self__.__module__, 'builtins')
+        self.assertEqual(decimal.Decimal.from_float.__module__, 'decimal')
+        self.assertEqual(decimal.Decimal.from_float.__self__.__module__, 'decimal')
+
+        # builtin staticmethod:
+        self.assertEqual(bytes.maketrans.__module__, 'builtins')
+
     def test_builtin__qualname__(self):
         import time
 

Misc/NEWS.d/next/Core and Builtins/2024-02-10-05-42-26.gh-issue-115231.6T7dzi.rst

@@ -0,0 +1,2 @@
+Setup ``__module__`` attribute for built-in class/static methods.  Patch by
+Sergey B Kirpichev.

Objects/descrobject.c

@@ -130,7 +130,11 @@ classmethod_get(PyObject *self, PyObject *obj, PyObject *type)
     if (descr->d_method->ml_flags & METH_METHOD) {
         cls = descr->d_common.d_type;
     }
-    return PyCMethod_New(descr->d_method, type, NULL, cls);
+    PyObject *mod = PyObject_GetAttr((PyObject*)type, &_Py_ID(__module__));
+    PyErr_Clear();
+    PyObject *result = PyCMethod_New(descr->d_method, type, mod, cls);
+    Py_XDECREF(mod);
+    return result;
 }
 
 static PyObject *

Objects/typeobject.c

@@ -6653,7 +6653,10 @@ type_add_method(PyTypeObject *type, PyMethodDef *meth)
         descr = PyDescr_NewClassMethod(type, meth);
     }
     else if (meth->ml_flags & METH_STATIC) {
-        PyObject *cfunc = PyCFunction_NewEx(meth, (PyObject*)type, NULL);
+        PyObject *mod = PyObject_GetAttr((PyObject*)type, &_Py_ID(__module__));
+        PyErr_Clear();
+        PyObject *cfunc = PyCFunction_NewEx(meth, (PyObject*)type, mod);
+        Py_XDECREF(mod);
         if (cfunc == NULL) {
             return -1;
         }