Issue #23631: Fix traceback.format_list when a traceback has been mutated.
diff --git a/Lib/traceback.py b/Lib/traceback.py
index 0ac1819..f7705cd 100644
--- a/Lib/traceback.py
+++ b/Lib/traceback.py
@@ -348,11 +348,17 @@
This method supports the older Python API. Each tuple should be a
4-tuple with (filename, lineno, name, line) elements.
"""
- if isinstance(a_list, StackSummary):
- return StackSummary(a_list)
+ # While doing a fast-path check for isinstance(a_list, StackSummary) is
+ # appealing, idlelib.run.cleanup_traceback and other similar code may
+ # break this by making arbitrary frames plain tuples, so we need to
+ # check on a frame by frame basis.
result = StackSummary()
- for filename, lineno, name, line in a_list:
- result.append(FrameSummary(filename, lineno, name, line=line))
+ for frame in a_list:
+ if isinstance(frame, FrameSummary):
+ result.append(frame)
+ else:
+ filename, lineno, name, line = frame
+ result.append(FrameSummary(filename, lineno, name, line=line))
return result
def format(self):