don't support namedtuple helpers when unnamed fields are present

Signed-off-by: Filipe Laíns <[email protected]>

Author: FFY00

Lib/test/test_structseq.py

@@ -1,6 +1,7 @@
 import os
 import time
 import unittest
+import _testcapi
 
 
 class StructSeqTest(unittest.TestCase):
@@ -155,6 +156,14 @@ def test_tuple_asdict(self):
             'tm_isdst': 0,
         })
 
+    def test_tuple_attributes_unnamed(self):
+        for key in ['_fields', '_field_defaults']:
+            self.assertNotIn(key, dir(_testcapi.MixedNamedTuple))
+
+    def test_asdict_unnamed(self):
+        t = _testcapi.MixedNamedTuple((0, 1))
+        self.assertRaises(ValueError, t._asdict)
+
 
 if __name__ == "__main__":
     unittest.main()

Modules/_testcapimodule.c

@@ -3946,13 +3946,28 @@ static struct PyModuleDef _testcapimodule = {
     NULL
 };
 
+static PyStructSequence_Field MixedNamedTuple_fields[] = {
+    {"something", "some named entry"},
+    {NULL, "some unnamed entry"},
+    {0}
+};
+
+static PyStructSequence_Desc MixedNamedTuple_desc = {
+    .name = "_testcpi.MixedNamedTuple",
+    .doc = PyDoc_STR("Example of a named tuple with both named and unnamed fields."),
+    .fields = MixedNamedTuple_fields,
+    .n_in_sequence = 2
+};
+
+
 /* Per PEP 489, this module will not be converted to multi-phase initialization
  */
 
 PyMODINIT_FUNC
 PyInit__testcapi(void)
 {
     PyObject *m;
+    PyTypeObject *type;
 
     m = PyModule_Create(&_testcapimodule);
     if (m == NULL)
@@ -4047,6 +4062,13 @@ PyInit__testcapi(void)
                            (PyObject *) &ContainerNoGC_type) < 0)
         return NULL;
 
+    MixedNamedTuple_desc.fields[1].name = PyStructSequence_UnnamedField;
+    type = PyStructSequence_NewType(&MixedNamedTuple_desc);
+    if (type == NULL)
+        return NULL;
+    if (PyModule_AddType(m, type) < 0)
+        return NULL;
+
     /* Include tests from the _testcapi/ directory */
     if (_PyTestCapi_Init_Vectorcall(m) < 0) {
         return NULL;

Objects/structseq.c

@@ -376,6 +376,12 @@ structseq_asdict(PyStructSequence* self, PyObject *Py_UNUSED(ignored))
     n_visible_fields = VISIBLE_SIZE(self);
     n_unnamed_fields = UNNAMED_FIELDS(self);
 
+    if (n_unnamed_fields != 0) {
+        PyErr_SetString(PyExc_ValueError, "named tuples with both named and "
+                                          "unnamed fields don't support _asdict");
+        return NULL;
+    }
+
     dict = PyDict_New();
     if (!dict)
         return NULL;
@@ -434,7 +440,7 @@ initialize_structseq_dict(PyStructSequence_Desc *desc, PyObject* dict,
     SET_DICT_FROM_SIZE(real_length_key, n_members);
     SET_DICT_FROM_SIZE(unnamed_fields_key, n_unnamed_members);
 
-    // Prepare and set __match_args__ and _fields
+    // Prepare and set __match_args__
     Py_ssize_t i, k;
     PyObject* keys = PyTuple_New(desc->n_in_sequence);
     if (keys == NULL) {
@@ -461,20 +467,24 @@ initialize_structseq_dict(PyStructSequence_Desc *desc, PyObject* dict,
         goto error;
     }
 
-    if (PyDict_SetItemString(dict, named_fields_list_key, keys) < 0) {
-        goto error;
-    }
+    // Set _field and _field_defaults when we have no unnammed members
+    if (n_unnamed_members == 0) {
+        if (PyDict_SetItemString(dict, named_fields_list_key, keys) < 0) {
+            goto error;
+        }
 
-    // Set _fields_defaults to an empty dir, as we don't support defaults
-    defaults = PyDict_New();
-    if (!defaults)
-        goto error;
+        // Set _fields_defaults to an empty dir, as we don't support defaults
+        defaults = PyDict_New();
+        if (!defaults)
+            goto error;
 
-    if (PyDict_SetItemString(dict, named_fields_defaults_key, defaults) < 0) {
-        goto error;
+        if (PyDict_SetItemString(dict, named_fields_defaults_key, defaults) < 0) {
+            goto error;
+        }
+
+        Py_DECREF(defaults);
     }
 
-    Py_DECREF(defaults);
     Py_DECREF(keys);
     return 0;