Several places in _PyEval_MatchClass call PyList_Append without checking the return value (e.g., https://github.com/python/cpython/blob/fc2cb86d210555d509debaeefd370d5331cd9d93/Python/ceval.c#L509C13-L509C26). However, PyList_Append can fail. It will only fail if we're out of memory or if we passed a non-list, so it's unlikely to come up in practice, but we should still check for errors.

cc @brandtbucher for pattern matching

Linked PRs

• gh-110237: Check PyList_Append for errors in _PyEval_MatchClass #110238
• [3.12] gh-110237: Check PyList_Append for errors in _PyEval_MatchClass (GH-110238) #110511
• [3.11] gh-110237: Check PyList_Append for errors in _PyEval_MatchClass (GH-110238) #110512