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prevent unacceptable bases from becoming bases through multiple inheritance (#24806)

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This commit is contained in:
Benjamin Peterson 2015-10-06 19:36:54 -07:00
parent 106ddf07b3
commit bd6c41a185
3 changed files with 40 additions and 6 deletions
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31
Lib/test/test_descr.py
View File

@ -3735,6 +3735,37 @@ order (MRO) for bases """
else:
assert 0, "best_base calculation found wanting"
def test_unsubclassable_types(self):
with self.assertRaises(TypeError):
class X(type(None)):
pass
with self.assertRaises(TypeError):
class X(object, type(None)):
pass
with self.assertRaises(TypeError):
class X(type(None), object):
pass
class O(object):
pass
with self.assertRaises(TypeError):
class X(O, type(None)):
pass
with self.assertRaises(TypeError):
class X(type(None), O):
pass
class X(object):
pass
with self.assertRaises(TypeError):
X.__bases__ = type(None),
with self.assertRaises(TypeError):
X.__bases__ = object, type(None)
with self.assertRaises(TypeError):
X.__bases__ = type(None), object
with self.assertRaises(TypeError):
X.__bases__ = O, type(None)
with self.assertRaises(TypeError):
X.__bases__ = type(None), O
def test_mutable_bases_with_failing_mro(self):
# Testing mutable bases with failing mro...

3
Misc/NEWS
View File

@ -10,6 +10,9 @@ Release date: tba
Core and Builtins
-----------------
- Issue #24806: Prevent builtin types that are not allowed to be subclassed from
being subclassed through multiple inheritance.
- Issue #24848: Fixed a number of bugs in UTF-7 decoding of misformed data.
- Issue #25280: Import trace messages emitted in verbose (-v) mode are no

12
Objects/typeobject.c
View File

@ -1937,6 +1937,12 @@ best_base(PyObject *bases)
if (PyType_Ready(base_i) < 0)
return NULL;
}
if (!PyType_HasFeature(base_i, Py_TPFLAGS_BASETYPE)) {
PyErr_Format(PyExc_TypeError,
"type '%.100s' is not an acceptable base type",
base_i->tp_name);
return NULL;
}
candidate = solid_base(base_i);
if (winner == NULL) {
winner = candidate;
@ -2317,12 +2323,6 @@ type_new(PyTypeObject *metatype, PyObject *args, PyObject *kwds)
if (base == NULL) {
goto error;
}
if (!PyType_HasFeature(base, Py_TPFLAGS_BASETYPE)) {
PyErr_Format(PyExc_TypeError,
"type '%.100s' is not an acceptable base type",
base->tp_name);
goto error;
}
dict = PyDict_Copy(orig_dict);
if (dict == NULL)