python / python/cpython

AST: ensure kw_defaults is always allocated for kw-only args (fix NULL deref)

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interpreter-core topic-parser type-bug
Dominant language
Python
Stars
77.2k
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PR merge metrics
PR metrics pending

Description

Bug report

Bug description:

has_kwonlydefaults can null-deref kw_defaults when the AST arguments node is constructed with kwonlyargs but a null kw_defaults.

CPython versions tested on:

3.15, CPython main branch

Operating systems tested on:

macOS

Linked PRs
  • gh-142463

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the AST arguments-node handling around has_kwonlydefaults, kwonlyargs, and kw_defaults. Review linked PR gh-142463 and verify that constructing the node with kwonlyargs and a null kw_defaults no longer causes a null dereference, with regression coverage for that case.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
compilers
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
25/100

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