gh-145876: preserve AttributeError in dict unpacking by zakiscoding · Pull Request #145878 · python/cpython

Pull request overview

This PR adjusts dict-unpacking ({**obj} / DICT_UPDATE) error handling so that AttributeError raised from within a mapping’s keys() / __getitem__ is propagated, instead of being incorrectly rewritten as TypeError: '... object is not a mapping'.

Changes:

• Update DICT_UPDATE to only convert AttributeError into “not a mapping” when update_o truly lacks a keys attribute; otherwise restore and propagate the original exception.
• Regenerate the tier-1 interpreter cases to include the updated error-handling logic.
• Add doctest coverage ensuring AttributeError from keys() / __getitem__ is preserved during dict unpacking.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
Python/generated_cases.c.h	Regenerated tier-1 interpreter DICT_UPDATE case to preserve AttributeError from mapping internals.
Python/bytecodes.c	Updates the DICT_UPDATE bytecode definition’s error translation logic.
Lib/test/test_unpack_ex.py	Adds doctests to ensure {**obj} propagates AttributeError raised by keys() / __getitem__.

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