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gh-152405 Safer mapping proxy comparisons #152489

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da-woods wants to merge 7 commits into from
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gh-152405 Safer mapping proxy comparisons #152489

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01b58de
gh-152405 Safer mapping proxy comparisons
da-woods Jun 28, 2026
f8b63a5
Fix 'w' type check
da-woods Jun 28, 2026
c1b3d47
Orderdict special case too
da-woods Jun 28, 2026
3e2f474
Appease linter
da-woods Jun 28, 2026
ed44817
Actually appease linter
da-woods Jun 28, 2026
6cdf9a0
Fix mappingproxy "or" too
da-woods Jun 28, 2026
d0d0833
Small formatting cleanup
da-woods Jun 28, 2026
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45 changes: 37 additions & 8 deletions Objects/descrobject.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1061,16 +1061,33 @@ static PyMappingMethods mappingproxy_as_mapping = {
0, /* mp_ass_subscript */
};

static int mappingproxy_is_known_dict_subclass_or(PyObject *o) {
return (PyAnyDict_CheckExact(o) || PyODict_CheckExact(o) ||
(PyAnyDict_Check(o) && Py_TYPE(o)->tp_as_number->nb_or == PyDict_Type.tp_as_number->nb_or)) ||
(PyODict_Check(o) && Py_TYPE(o)->tp_as_number->nb_or == PyODict_Type.tp_as_number->nb_or);
}

static PyObject *
mappingproxy_or(PyObject *left, PyObject *right)

@sobolevn sobolevn Jun 28, 2026

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I would prefer to keep this PR focused on one specific problem :)

We already have 3 versions, let's no make it even more complicated, please

@da-woods da-woods Jun 28, 2026

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Sorry! I promise I'm done changing this for now.

Obviously it can be split off separately if cleaner (but probably not worth it while the approach is still undecided).

{
if (PyObject_TypeCheck(left, &PyDictProxy_Type)) {
left = ((mappingproxyobject*)left)->mapping;
}
if (PyObject_TypeCheck(right, &PyDictProxy_Type)) {
right = ((mappingproxyobject*)right)->mapping;
if (PyObject_TypeCheck(right, &PyDictProxy_Type)) {
right = ((mappingproxyobject*)right)->mapping;
}
PyObject *left_mapping = ((mappingproxyobject*)left)->mapping;
if (mappingproxy_is_known_dict_subclass_or(right) || PyFrozenDict_CheckExact(left_mapping)) {
return PyNumber_Or(left_mapping, right);
}
} else {
assert(PyObject_TypeCheck(right, &PyDictProxy_Type));
PyObject *right_mapping = ((mappingproxyobject*)right)->mapping;
if (mappingproxy_is_known_dict_subclass_or(left) || PyFrozenDict_CheckExact(right_mapping)) {
return PyNumber_Or(left, right_mapping);
}
}
return PyNumber_Or(left, right);

// The non-mappingproxy "or" will have to deal with a mappingproxy.
Py_RETURN_NOTIMPLEMENTED;
}

static PyObject *
Expand Down Expand Up @@ -1229,14 +1246,26 @@ mappingproxy_traverse(PyObject *self, visitproc visit, void *arg)
return 0;
}

static int
mappingproxy_is_known_dict_subclass_richcompare(PyObject *o) {
return (PyAnyDict_CheckExact(o) || PyODict_CheckExact(o) ||
(PyAnyDict_Check(o) && Py_TYPE(o)->tp_richcompare == PyDict_Type.tp_richcompare) ||
(PyODict_Check(o) && Py_TYPE(o)->tp_richcompare == PyODict_Type.tp_richcompare));
}

static PyObject *
mappingproxy_richcompare(PyObject *self, PyObject *w, int op)
{
mappingproxyobject *v = (mappingproxyobject *)self;
if (op == Py_EQ || op == Py_NE) {
return PyObject_RichCompare(v->mapping, w, op);
mappingproxyobject *v = (mappingproxyobject *)self;
if (PyObject_TypeCheck(w, &PyDictProxy_Type)) {
w = ((mappingproxyobject *)w)->mapping;
}
if (mappingproxy_is_known_dict_subclass_richcompare(w) || PyFrozenDict_CheckExact(v->mapping)) {
return PyObject_RichCompare(v->mapping, w, op);
}
}
Py_RETURN_NOTIMPLEMENTED;
Py_RETURN_NOTIMPLEMENTED; // Defer to w's richcompare
}

static int
Expand Down
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