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GH-146096: Fix base exception group repr #146141

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GH-146096: Fix base exception group repr #146141

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2f0e336
Fix BaseExceptionGroup repr
sergey-miryanov Mar 18, 2026
007cac7
Add tests
sergey-miryanov Mar 18, 2026
4f9a6ba
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sergey-miryanov Mar 18, 2026
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12 changes: 12 additions & 0 deletions Lib/test/test_exception_group.py
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Original file line number Diff line number Diff line change
Expand Up @@ -234,6 +234,18 @@ class MyEG(ExceptionGroup):
"ExceptionGroup('test', deque([ValueError(1), TypeError(2)]))"
)

def test_repr_small_size_args(self):
eg = ExceptionGroup("msg", [ValueError()])
eg.args = ()
# repr of the ExceptionGroup with empty args should not crash
self.assertEqual(repr(eg), "ExceptionGroup('msg', (ValueError(),))")

eg.args = (1,)
# repr of the ExceptionGroup with 1-size args should not crash
self.assertEqual(repr(eg), "ExceptionGroup('msg', (ValueError(),))")



def test_repr_raises(self):
class MySeq(collections.abc.Sequence):
def __init__(self, raises):
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core_and_Builtins/2026-03-19-01-19-34.gh-issue-146096.R9tkJX.rst
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@@ -0,0 +1,2 @@
Fixed segmentation fault when called repr for BaseExceptionGroup with empty
or 1-size tuple args.
2 changes: 1 addition & 1 deletion Objects/exceptions.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1091,7 +1091,7 @@ BaseExceptionGroup_repr(PyObject *op)
* value of self.args[1]; but this can be mutable and go out-of-sync
* with self.exceptions. Instead, use self.exceptions for accuracy,
* making it look like self.args[1] for backwards compatibility. */
if (PyList_Check(PyTuple_GET_ITEM(self->args, 1))) {
if (PyTuple_GET_SIZE(self->args) == 2 && PyList_Check(PyTuple_GET_ITEM(self->args, 1))) {
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@iritkatriel iritkatriel Mar 18, 2026

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Do we need to check that it's a Tuple first?

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@dr-carlos dr-carlos Mar 18, 2026

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No, args is always converted to a tuple in its setter:
https://github.com/sergey-miryanov/cpython/blob/4f9a6ba7ba98a83d5594aacadcddb90696ffd5d7/Objects/exceptions.c#L351-L364

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@iritkatriel iritkatriel Mar 19, 2026

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Could add an assert just so it reads like it makes sense.

PyObject *exceptions_list = PySequence_List(self->excs);
if (!exceptions_list) {
return NULL;
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