bpo-44486: Make sure that modules always have a dictionary. (GH-26847)

* Make sure that modules always have a dictionary.

Author: markshannon

Lib/test/test_module.py

@@ -22,8 +22,8 @@ def test_uninitialized(self):
  # An uninitialized module has no __dict__ or __name__,
  # and __doc__ is None
  foo = ModuleType.__new__(ModuleType)
- self.assertTrue(foo.__dict__ is None)
- self.assertRaises(TypeError, dir, foo)
+ self.assertTrue(isinstance(foo.__dict__, dict))
+ self.assertEqual(dir(foo), [])
  try:
  s = foo.__name__
  self.fail("__name__ = %s" % repr(s))
@@ -318,15 +318,6 @@ def test_setting_annotations(self):
  del foo.__dict__['__annotations__']
 
  def test_annotations_getset_raises(self):
- # module has no dict, all operations fail
- foo = ModuleType.__new__(ModuleType)
- with self.assertRaises(TypeError):
- print(foo.__annotations__)
- with self.assertRaises(TypeError):
- foo.__annotations__ = {}
- with self.assertRaises(TypeError):
- del foo.__annotations__
-
  # double delete
  foo = ModuleType("foo")
  foo.__annotations__ = {}

Misc/NEWS.d/next/Core and Builtins/2021-06-22-10-55-23.bpo-44486.wct-9X.rst

@@ -0,0 +1,2 @@
+Modules will always have a dictionary, even when created by
+``types.ModuleType.__new__()``

Objects/moduleobject.c

@@ -64,8 +64,7 @@ module_init_dict(PyModuleObject *mod, PyObject *md_dict,
  _Py_IDENTIFIER(__package__);
  _Py_IDENTIFIER(__loader__);
 
- if (md_dict == NULL)
- return -1;
+ assert(md_dict != NULL);
  if (doc == NULL)
  doc = Py_None;
 
@@ -87,19 +86,41 @@ module_init_dict(PyModuleObject *mod, PyObject *md_dict,
  return 0;
 }
 
-
-PyObject *
-PyModule_NewObject(PyObject *name)
+static PyModuleObject *
+new_module_notrack(PyTypeObject *mt)
 {
  PyModuleObject *m;
- m = PyObject_GC_New(PyModuleObject, &PyModule_Type);
+ m = PyObject_GC_New(PyModuleObject, mt);
  if (m == NULL)
  return NULL;
  m->md_def = NULL;
  m->md_state = NULL;
  m->md_weaklist = NULL;
  m->md_name = NULL;
  m->md_dict = PyDict_New();
+ if (m->md_dict != NULL) {
+ return m;
+ }
+ Py_DECREF(m);
+ return NULL;
+}
+
+static PyObject *
+new_module(PyTypeObject *mt, PyObject *args, PyObject *kws)
+{
+ PyObject *m = (PyObject *)new_module_notrack(mt);
+ if (m != NULL) {
+ PyObject_GC_Track(m);
+ }
+ return m;
+}
+
+PyObject *
+PyModule_NewObject(PyObject *name)
+{
+ PyModuleObject *m = new_module_notrack(&PyModule_Type);
+ if (m == NULL)
+ return NULL;
  if (module_init_dict(m, m->md_dict, name, NULL) != 0)
  goto fail;
  PyObject_GC_Track(m);
@@ -728,43 +749,42 @@ module_getattro(PyModuleObject *m, PyObject *name)
  return attr;
  }
  PyErr_Clear();
- if (m->md_dict) {
- _Py_IDENTIFIER(__getattr__);
- getattr = _PyDict_GetItemIdWithError(m->md_dict, &PyId___getattr__);
- if (getattr) {
- return PyObject_CallOneArg(getattr, name);
- }
- if (PyErr_Occurred()) {
- return NULL;
- }
- mod_name = _PyDict_GetItemIdWithError(m->md_dict, &PyId___name__);
- if (mod_name && PyUnicode_Check(mod_name)) {
- Py_INCREF(mod_name);
- PyObject *spec = _PyDict_GetItemIdWithError(m->md_dict, &PyId___spec__);
- if (spec == NULL && PyErr_Occurred()) {
- Py_DECREF(mod_name);
- return NULL;
- }
- Py_XINCREF(spec);
- if (_PyModuleSpec_IsInitializing(spec)) {
- PyErr_Format(PyExc_AttributeError,
- "partially initialized "
- "module '%U' has no attribute '%U' "
- "(most likely due to a circular import)",
- mod_name, name);
- }
- else {
- PyErr_Format(PyExc_AttributeError,
- "module '%U' has no attribute '%U'",
- mod_name, name);
- }
- Py_XDECREF(spec);
+ assert(m->md_dict != NULL);
+ _Py_IDENTIFIER(__getattr__);
+ getattr = _PyDict_GetItemIdWithError(m->md_dict, &PyId___getattr__);
+ if (getattr) {
+ return PyObject_CallOneArg(getattr, name);
+ }
+ if (PyErr_Occurred()) {
+ return NULL;
+ }
+ mod_name = _PyDict_GetItemIdWithError(m->md_dict, &PyId___name__);
+ if (mod_name && PyUnicode_Check(mod_name)) {
+ Py_INCREF(mod_name);
+ PyObject *spec = _PyDict_GetItemIdWithError(m->md_dict, &PyId___spec__);
+ if (spec == NULL && PyErr_Occurred()) {
  Py_DECREF(mod_name);
  return NULL;
  }
- else if (PyErr_Occurred()) {
- return NULL;
+ Py_XINCREF(spec);
+ if (_PyModuleSpec_IsInitializing(spec)) {
+ PyErr_Format(PyExc_AttributeError,
+ "partially initialized "
+ "module '%U' has no attribute '%U' "
+ "(most likely due to a circular import)",
+ mod_name, name);
  }
+ else {
+ PyErr_Format(PyExc_AttributeError,
+ "module '%U' has no attribute '%U'",
+ mod_name, name);
+ }
+ Py_XDECREF(spec);
+ Py_DECREF(mod_name);
+ return NULL;
+ }
+ else if (PyErr_Occurred()) {
+ return NULL;
  }
  PyErr_Format(PyExc_AttributeError,
  "module has no attribute '%U'", name);
@@ -948,7 +968,7 @@ PyTypeObject PyModule_Type = {
  0, /* tp_descr_set */
  offsetof(PyModuleObject, md_dict), /* tp_dictoffset */
  module___init__, /* tp_init */
- PyType_GenericAlloc, /* tp_alloc */
- PyType_GenericNew, /* tp_new */
+ 0,  /* tp_alloc */
+ new_module,  /* tp_new */
  PyObject_GC_Del, /* tp_free */
 };

Python/ceval.c

@@ -3337,6 +3337,7 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
  _PyLoadAttrCache *cache1 = &caches[-1].load_attr;
  DEOPT_IF(!PyModule_CheckExact(owner), LOAD_ATTR);
  PyDictObject *dict = (PyDictObject *)((PyModuleObject *)owner)->md_dict;
+ assert(dict != NULL);
  DEOPT_IF(dict->ma_keys->dk_version != cache1->dk_version_or_hint, LOAD_ATTR);
  assert(dict->ma_keys->dk_kind == DICT_KEYS_UNICODE);
  assert(cache0->index < dict->ma_keys->dk_nentries);