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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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30
Python/bltinmodule.c
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@ -35,9 +35,10 @@ int Py_HasFileSystemDefaultEncoding = 1;
static PyObject *
builtin___build_class__(PyObject *self, PyObject *args, PyObject *kwds)
{
PyObject *func, *name, *bases, *mkw, *meta, *prep, *ns, *cell;
PyObject *func, *name, *bases, *mkw, *meta, *winner, *prep, *ns, *cell;
PyObject *cls = NULL;
Py_ssize_t nargs, nbases;
int isclass;
assert(args != NULL);
if (!PyTuple_Check(args)) {
@ -82,17 +83,42 @@ builtin___build_class__(PyObject *self, PyObject *args, PyObject *kwds)
Py_DECREF(bases);
return NULL;
}
/* metaclass is explicitly given, check if it's indeed a class */
isclass = PyType_Check(meta);
}
}
if (meta == NULL) {
if (PyTuple_GET_SIZE(bases) == 0)
/* if there are no bases, use type: */
if (PyTuple_GET_SIZE(bases) == 0) {
meta = (PyObject *) (&PyType_Type);
}
/* else get the type of the first base */
else {
PyObject *base0 = PyTuple_GET_ITEM(bases, 0);
meta = (PyObject *) (base0->ob_type);
}
Py_INCREF(meta);
isclass = 1; /* meta is really a class */
}
if (isclass) {
/* meta is really a class, so check for a more derived
metaclass, or possible metaclass conflicts: */
winner = (PyObject *)_PyType_CalculateMetaclass((PyTypeObject *)meta,
bases);
if (winner == NULL) {
Py_DECREF(meta);
Py_XDECREF(mkw);
Py_DECREF(bases);
return NULL;
}
if (winner != meta) {
Py_DECREF(meta);
meta = winner;
Py_INCREF(meta);
}
}
/* else: meta is not a class, so we cannot do the metaclass
calculation, so we will use the explicitly given object as it is */
prep = PyObject_GetAttrString(meta, "__prepare__");
if (prep == NULL) {
if (PyErr_ExceptionMatches(PyExc_AttributeError)) {