Issue #20204: Deprecation warning is now raised for builtin type without the

__module__ attribute.

Doc/whatsnew/3.5.rst

@@ -561,3 +561,8 @@ Changes in the C API
 * Removed non-documented macro :c:macro:`PyObject_REPR` which leaked references.
   Use format character ``%R`` in :c:func:`PyUnicode_FromFormat`-like functions
   to format the :func:`repr` of the object.
+
+* Because the lack of the :attr:`__module__` attribute breaks pickling and
+  introspection, a deprecation warning now is raised for builtin type without
+  the :attr:`__module__` attribute.  Would be an AttributeError in future.
+  (:issue:`20204`)

Misc/NEWS

@@ -88,6 +88,12 @@ Build
 - Issue #23445: pydebug builds now use "gcc -Og" where possible, to make
   the resulting executable faster.
 
+C API
+-----
+
+- Issue #20204: Deprecation warning is now raised for builtin type without the
+  __module__ attribute.
+
 Windows
 -------
 

Objects/typeobject.c

@@ -2808,6 +2808,12 @@ PyType_FromSpecWithBases(PyType_Spec *spec, PyObject *bases)
         _PyDict_SetItemId(type->tp_dict, &PyId___module__,
             PyUnicode_FromStringAndSize(
                 spec->name, (Py_ssize_t)(s - spec->name)));
+    else {
+        if (PyErr_WarnFormat(PyExc_DeprecationWarning, 1,
+                "builtin type %.200s has no the __module__ attribute",
+                spec->name))
+            goto fail;
+    }
 
     return (PyObject*)res;