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GeezerVison is showing github.com — [3.14] gh-146056: Fix repr() for lists and tuples containing NULLs (GH-146129) (alt) by serhiy-storchaka · Pull Request #146204 · python/cpython

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@serhiy-storchaka

@serhiy-storchaka serhiy-storchaka commented Mar 20, 2026 •
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(cherry picked from commit 0f2246b)

This is an alternative to #146155 which only fixes PyUnicodeWriter_WriteRepr() for internal use, leaving users with the broken variant.

  • Issue: Crash in repr() for lists containing NULLs #146056

📚 Documentation preview 📚: https://cpython-previews--146204.org.readthedocs.build/

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@serhiy-storchaka @vstinner
[3.14] pythongh-146056: Fix list.__repr__() for lists containing NULLs (
fec7f55 
pythonGH-146129)

(cherry picked from commit 0f2246b)

Co-authored-by: Serhiy Storchaka <[email protected]>
Co-authored-by: Victor Stinner <[email protected]>
@serhiy-storchaka
serhiy-storchaka requested a review from vstinner March 20, 2026 11:47
@serhiy-storchaka serhiy-storchaka added the needs backport to 3.13 only security fixes label Mar 20, 2026
@bedevere-app bedevere-app Bot mentioned this pull request Mar 20, 2026
Crash in repr() for lists containing NULLs #146056
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@bedevere-app bedevere-app Bot added the awaiting core review label Mar 20, 2026
@bedevere-app bedevere-app Bot mentioned this pull request Mar 20, 2026
gh-146056: Fix repr() for lists and tuples containing NULLs #146129
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@serhiy-storchaka
Merge branch '3.14' into list-repr-null-3.14
a4ea518
@serhiy-storchaka serhiy-storchaka changed the title [3.14] gh-146056: Fix list.__repr__() for lists containing NULLs (GH-146129) [3.14] gh-146056: Fix list.__repr__() for lists containing NULLs (GH-146129) (alt) Mar 20, 2026
vstinner
vstinner reviewed Mar 20, 2026
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I don't think that this hack is needed. I would prefer to only change tuple_repr() and list_repr().

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Comment thread Misc/NEWS.d/next/C_API/2026-03-18-20-18-59.gh-issue-146056.nnZIgp.rst Outdated
@@ -0,0 +1 @@
:c:func:`PyUnicodeWriter_WriteRepr` now supports ``NULL`` argument.

@vstinner vstinner Mar 20, 2026

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This is no longer true.

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Comment thread Include/cpython/unicodeobject.h
PyObject *obj);
#if defined(Py_BUILD_CORE) || defined(Py_BUILD_CORE_MODULE)
#define PyUnicodeWriter_WriteRepr _PyUnicodeWriter_WriteReprTrue
#endif

@vstinner vstinner Mar 20, 2026

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It looks like a bad hack to me. I don't think that it's needed: only tuple_repr() and list_repr() should be modified to accept NULL: #146155 (comment), other functions cannot call PyUnicodeWriter_WriteRepr() with NULL.

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@serhiy-storchaka serhiy-storchaka Mar 20, 2026

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I tried to minimize the diff. If you prefer, we can simply replace PyUnicodeWriter_WriteRepr with _PyUnicodeWriter_WriteReprTrue. This will make future backports more difficult.

We cannot be sure that this is not needed until we analyze every use of PyUnicodeWriter_WriteRepr. This will take a time. Even if it is not needed right now, it can be needed after future backports.

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@serhiy-storchaka
Delete Misc/NEWS.d/next/C_API/2026-03-18-20-18-59.gh-issue-146056.nnZ…
5e3172c 
…Igp.rst
@serhiy-storchaka serhiy-storchaka changed the title [3.14] gh-146056: Fix list.__repr__() for lists containing NULLs (GH-146129) (alt) [3.14] gh-146056: Fix repr() for lists and tuples containing NULLs (GH-146129) (alt) Mar 20, 2026
@serhiy-storchaka serhiy-storchaka closed this Mar 22, 2026
@serhiy-storchaka
serhiy-storchaka deleted the list-repr-null-3.14 branch March 22, 2026 07:27
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awaiting core review needs backport to 3.13 only security fixes

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@serhiy-storchaka @vstinner
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