gh-113358: Fix rendering tracebacks with exceptions with a broken __getattr__ (GH-113359)

Co-authored-by: Irit Katriel <1055913+iritkatriel@users.noreply.github.com>

Author: perrinjerome

Lib/test/test_traceback.py

@@ -2209,6 +2209,20 @@ def __repr__(self):
  err_msg = "b'please do not show me as numbers'"
  self.assertEqual(self.get_report(e), vanilla + err_msg + '\n')
 
+ # an exception with a broken __getattr__ raising a non expected error
+ class BrokenException(Exception):
+ broken = False
+ def __getattr__(self, name):
+ if self.broken:
+ raise ValueError(f'no {name}')
+
+ e = BrokenException(123)
+ vanilla = self.get_report(e)
+ e.broken = True
+ self.assertEqual(
+ self.get_report(e),
+ vanilla + "Ignored error getting __notes__: ValueError('no __notes__')\n")
+
  def test_exception_with_multiple_notes(self):
  for e in [ValueError(42), SyntaxError('bad syntax')]:
  with self.subTest(e=e):

Lib/traceback.py

@@ -1051,7 +1051,11 @@ def __init__(self, exc_type, exc_value, exc_traceback, *, limit=None,
  # Capture now to permit freeing resources: only complication is in the
  # unofficial API _format_final_exc_line
  self._str = _safe_string(exc_value, 'exception')
- self.__notes__ = getattr(exc_value, '__notes__', None)
+ try:
+ self.__notes__ = getattr(exc_value, '__notes__', None)
+ except Exception as e:
+ self.__notes__ = [
+ f'Ignored error getting __notes__: {_safe_string(e, '__notes__', repr)}']
 
  self._is_syntax_error = False
  self._have_exc_type = exc_type is not None

Misc/NEWS.d/next/Library/2023-12-21-14-55-06.gh-issue-113358.nRkiSL.rst

@@ -0,0 +1 @@
+Fix rendering tracebacks with exceptions with a broken __getattr__