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Issue 1294232: Fix errors in metaclass calculation affecting some cases of metaclass inheritance. Patch by Daniel Urban.

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This commit is contained in:
Nick Coghlan 2011-10-23 22:04:16 +10:00
parent 711f87ca7d
commit de31b191e5
5 changed files with 242 additions and 22 deletions
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61
Objects/typeobject.c
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@ -1912,6 +1912,42 @@ PyType_GetFlags(PyTypeObject *type)
return type->tp_flags;
}
/* Determine the most derived metatype. */
PyTypeObject *
_PyType_CalculateMetaclass(PyTypeObject *metatype, PyObject *bases)
{
Py_ssize_t i, nbases;
PyTypeObject *winner;
PyObject *tmp;
PyTypeObject *tmptype;
/* Determine the proper metatype to deal with this,
and check for metatype conflicts while we're at it.
Note that if some other metatype wins to contract,
it's possible that its instances are not types. */
nbases = PyTuple_GET_SIZE(bases);
winner = metatype;
for (i = 0; i < nbases; i++) {
tmp = PyTuple_GET_ITEM(bases, i);
tmptype = Py_TYPE(tmp);
if (PyType_IsSubtype(winner, tmptype))
continue;
if (PyType_IsSubtype(tmptype, winner)) {
winner = tmptype;
continue;
}
/* else: */
PyErr_SetString(PyExc_TypeError,
"metaclass conflict: "
"the metaclass of a derived class "
"must be a (non-strict) subclass "
"of the metaclasses of all its bases");
return NULL;
}
return winner;
}
static PyObject *
type_new(PyTypeObject *metatype, PyObject *args, PyObject *kwds)
{
@ -1955,28 +1991,12 @@ type_new(PyTypeObject *metatype, PyObject *args, PyObject *kwds)
&PyDict_Type, &dict))
return NULL;
/* Determine the proper metatype to deal with this,
and check for metatype conflicts while we're at it.
Note that if some other metatype wins to contract,
it's possible that its instances are not types. */
nbases = PyTuple_GET_SIZE(bases);
winner = metatype;
for (i = 0; i < nbases; i++) {
tmp = PyTuple_GET_ITEM(bases, i);
tmptype = Py_TYPE(tmp);
if (PyType_IsSubtype(winner, tmptype))
continue;
if (PyType_IsSubtype(tmptype, winner)) {
winner = tmptype;
continue;
}
PyErr_SetString(PyExc_TypeError,
"metaclass conflict: "
"the metaclass of a derived class "
"must be a (non-strict) subclass "
"of the metaclasses of all its bases");
/* Determine the proper metatype to deal with this: */
winner = _PyType_CalculateMetaclass(metatype, bases);
if (winner == NULL) {
return NULL;
}
if (winner != metatype) {
if (winner->tp_new != type_new) /* Pass it to the winner */
return winner->tp_new(winner, args, kwds);
@ -1984,6 +2004,7 @@ type_new(PyTypeObject *metatype, PyObject *args, PyObject *kwds)
}
/* Adjust for empty tuple bases */
nbases = PyTuple_GET_SIZE(bases);
if (nbases == 0) {
bases = PyTuple_Pack(1, &PyBaseObject_Type);
if (bases == NULL)