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gh-110782: Fix crash when TypeVar is constructed with keyword args #110784

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Merged
JelleZijlstra merged 2 commits into from
Oct 12, 2023
Merged

gh-110782: Fix crash when TypeVar is constructed with keyword args #110784

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fb598e7
gh-110782: Fix crash when TypeVar is constructed with keyword args
JelleZijlstra Oct 12, 2023
7558e8e
Merge branch 'main' into tvkw
AlexWaygood Oct 12, 2023
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gh-110782: Fix crash when TypeVar is constructed with keyword args
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@JelleZijlstra
JelleZijlstra committed Oct 12, 2023
commit fb598e7568ce390aeedaaa3b03fb68d474c279c0
6 changes: 6 additions & 0 deletions Lib/test/test_typing.py
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Original file line number Diff line number Diff line change
Expand Up @@ -554,6 +554,12 @@ def test_many_weakrefs(self):
vals[x] = cls(str(x))
del vals

def test_constructor(self):
T = TypeVar(name="T")
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@gvanrossum gvanrossum Oct 12, 2023

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I find this form offensive, but since we allowed it in 3.11 I guess we have to keep supporting it, and we can't just make it an error (not crashing of course). (It's especially weird since a type var with constraints requires the name to be positional.)

self.assertEqual(T.__name__, "T")
self.assertEqual(T.__constraints__, ())
self.assertIs(T.__bound__, None)


def template_replace(templates: list[str], replacements: dict[str, list[str]]) -> list[tuple[str]]:
"""Renders templates with possible combinations of replacements.
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2023-10-12-15-03-24.gh-issue-110782.EqzIzi.rst
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@@ -0,0 +1,2 @@
Fix crash when :class:`typing.TypeVar` is constructed with a keyword
argument. Patch by Jelle Zijlstra.
38 changes: 20 additions & 18 deletions Objects/typevarobject.c
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Expand Up @@ -364,24 +364,26 @@ typevar_new_impl(PyTypeObject *type, PyObject *name, PyObject *constraints,
}
}

if (!PyTuple_CheckExact(constraints)) {
PyErr_SetString(PyExc_TypeError,
"constraints must be a tuple");
return NULL;
}
Py_ssize_t n_constraints = PyTuple_GET_SIZE(constraints);
if (n_constraints == 1) {
PyErr_SetString(PyExc_TypeError,
"A single constraint is not allowed");
Py_XDECREF(bound);
return NULL;
} else if (n_constraints == 0) {
constraints = NULL;
} else if (bound != NULL) {
PyErr_SetString(PyExc_TypeError,
"Constraints cannot be combined with bound=...");
Py_XDECREF(bound);
return NULL;
if (constraints != NULL) {
if (!PyTuple_CheckExact(constraints)) {
PyErr_SetString(PyExc_TypeError,
"constraints must be a tuple");
return NULL;
}
Py_ssize_t n_constraints = PyTuple_GET_SIZE(constraints);
if (n_constraints == 1) {
PyErr_SetString(PyExc_TypeError,
"A single constraint is not allowed");
Py_XDECREF(bound);
return NULL;
} else if (n_constraints == 0) {
constraints = NULL;
} else if (bound != NULL) {
PyErr_SetString(PyExc_TypeError,
"Constraints cannot be combined with bound=...");
Py_XDECREF(bound);
return NULL;
}
}
PyObject *module = caller();
if (module == NULL) {
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