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GeezerVison is showing github.com — GH-146096: Fix base exception group repr by sergey-miryanov · Pull Request #146141 · python/cpython

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sergey-miryanov commented Mar 18, 2026 •

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Fix segfault when calling repr for BaseExceptionGroup.

cc @dr-carlos

Issue: Out-of-bounds tuple access in BaseExceptionGroup_repr #146096

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sergey-miryanov added 3 commits

March 19, 2026 01:16


          Fix BaseExceptionGroup repr

2f0e336


          Add tests

007cac7


          Add news entry

4f9a6ba

sergey-miryanov requested a review from iritkatriel as a code owner

March 18, 2026 20:20

bedevere-app Bot mentioned this pull request

Mar 18, 2026

Out-of-bounds tuple access in BaseExceptionGroup_repr #146096

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Mar 18, 2026

sergey-miryanov requested review from picnixz and removed request for iritkatriel

March 18, 2026 20:21

dr-carlos commented Mar 18, 2026 •

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Thanks for the fix @sergey-miryanov! All looks good to me.
My apologies for not considering that args was mutable in the first implementation!

It's a pity that we don't preserve the list-like repr (ExceptionGroup('msg', [ValueError()])) in this case. But mutating the args to something without an exceptions list in it seems like a weird enough use case that we can just do this?
If this is something that people actually do (why?), we could just set the self->excs_str in all cases, but that can be quite inefficient and I'd really prefer not to.

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iritkatriel reviewed

Mar 18, 2026

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Objects/exceptions.c

		* 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))) {

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 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 Mar 19, 2026

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

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sergey-miryanov Mar 19, 2026

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Done

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iritkatriel approved these changes

Mar 19, 2026

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bedevere-app Bot added awaiting merge and removed awaiting review labels

Mar 19, 2026


          Add assertion

5fdaa02

sergey-miryanov commented Mar 19, 2026

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I'm not sure that failed test related to change.

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          Merge branch 'main' into bug/146096-fix-base-exception-group-repr

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iritkatriel merged commit ced6460 into python:main

Mar 19, 2026

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bedevere-app Bot removed the awaiting merge label

Mar 19, 2026

sergey-miryanov deleted the bug/146096-fix-base-exception-group-repr branch

March 19, 2026 11:26

sergey-miryanov commented Mar 19, 2026

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Thanks all!

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pablogsal mentioned this pull request

Apr 4, 2026

gh-130273: Fix traceback color output with unicode characters #142529

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ljfp pushed a commit to ljfp/cpython that referenced this pull request

Apr 25, 2026


          pythonGH-146096: Fix segfault in BaseExceptionGroup repr (python#146141)

a1de9c6

encukou commented Sep 3, 2026

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The cause of the segfault, #141732, was backported to 3.13 & 3.14. The reproducer crashes on both:

eg = ExceptionGroup("msg", [ValueError()])
eg.args = ()
# repr of the ExceptionGroup with empty args should not crash
print(repr(eg), "ExceptionGroup('msg', (ValueError(),))")

I'll backport the fix there.

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encukou added needs backport to 3.13

only security fixes

needs backport to 3.14 bugs and security fixes labels

Sep 3, 2026

miss-islington-app Bot commented Sep 3, 2026

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Thanks @sergey-miryanov for the PR, and @iritkatriel for merging it 🌮🎉.. I'm working now to backport this PR to: 3.14.
🐍🍒⛏🤖 I'm not a witch! I'm not a witch!

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miss-islington-app Bot commented Sep 3, 2026

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Thanks @sergey-miryanov for the PR, and @iritkatriel for merging it 🌮🎉.. I'm working now to backport this PR to: 3.13.
🐍🍒⛏🤖

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bedevere-app Bot commented Sep 3, 2026

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GH-156903 is a backport of this pull request to the 3.13 branch.

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bedevere-app Bot removed the needs backport to 3.13 only security fixes label

Sep 3, 2026

bedevere-app Bot commented Sep 3, 2026

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GH-156904 is a backport of this pull request to the 3.14 branch.

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bedevere-app Bot removed the needs backport to 3.14 bugs and security fixes label

Sep 3, 2026

encukou pushed a commit that referenced this pull request

Sep 4, 2026


          [3.14] GH-146096: Fix segfault in BaseExceptionGroup repr (GH-146141) (…

1cb0003

…GH-156904)

(cherry picked from commit ced6460)

Co-authored-by: Sergey Miryanov <[email protected]>

encukou pushed a commit that referenced this pull request

Sep 4, 2026


          [3.13] GH-146096: Fix segfault in BaseExceptionGroup repr (GH-146141) (…

9ce6acd

…GH-156903)

(cherry picked from commit ced6460)

Co-authored-by: Sergey Miryanov <[email protected]>

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iritkatriel

iritkatriel approved these changes

picnixz

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sergey-miryanov commented Mar 18, 2026 •

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dr-carlos commented Mar 18, 2026 •

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