From d151f33d1728db290e7d50a063d613cc3b6101cd Mon Sep 17 00:00:00 2001
From: Basil Crow <me@basilcrow.com>
Date: Wed, 15 Jul 2026 12:41:43 -0700
Subject: [PATCH] gh-153782: Make traceback.print_list() delegate to
 format_list()

print_list() and format_list() each formatted a StackSummary with the
same expression, so their outputs agreed only by duplication. Route
print_list() through format_list() so print_list(x), keeping the two
public helpers from drifting, and add a regression test that
print_list() matches format_list() for tuple, FrameSummary, and
StackSummary inputs.
---
 Lib/test/test_traceback.py | 17 +++++++++++++++++
 Lib/traceback.py           |  2 +-
 Misc/ACKS                  |  1 +
 3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/Lib/test/test_traceback.py b/Lib/test/test_traceback.py
index e38d0942e463e9c..190618110d81a86 100644
--- a/Lib/test/test_traceback.py
+++ b/Lib/test/test_traceback.py
@@ -3431,6 +3431,23 @@ def test_format_smoke(self):
             ['  File "foo.py", line 1, in fred\n    line\n'],
             s.format())
 
+    def test_print_list_matches_format_list(self):
+        frame = traceback.FrameSummary('foo.py', 1, 'fred', line='line')
+        inputs = [
+            ('tuple', [('foo.py', 1, 'fred', 'line')]),
+            ('FrameSummary', [frame]),
+            ('StackSummary',
+             traceback.StackSummary.from_list([('foo.py', 1, 'fred', 'line')])),
+        ]
+        for input_type, extracted_list in inputs:
+            with self.subTest(input_type=input_type):
+                file = StringIO()
+                traceback.print_list(extracted_list, file=file)
+                self.assertEqual(
+                    file.getvalue(),
+                    ''.join(traceback.format_list(extracted_list)),
+                )
+
     def test_locals(self):
         linecache.updatecache('/foo.py', globals())
         c = test_code('/foo.py', 'method')
diff --git a/Lib/traceback.py b/Lib/traceback.py
index dcdab1f12e9a168..10784e6eadff656 100644
--- a/Lib/traceback.py
+++ b/Lib/traceback.py
@@ -72,7 +72,7 @@ def print_list(extracted_list, file=None):
     extract_stack() as a formatted stack trace to the given file."""
     if file is None:
         file = sys.stderr
-    for item in StackSummary.from_list(extracted_list).format():
+    for item in format_list(extracted_list):
         print(item, file=file, end="")
 
 def format_list(extracted_list):
diff --git a/Misc/ACKS b/Misc/ACKS
index fec00c1b272f4ea..7fee4a8ccc67d63 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -404,6 +404,7 @@ Laura Creighton
 Nick Crews
 Tyler Crompton
 Simon Cross
+Basil Crow
 Felipe Cruz
 Drew Csillag
 Alessandro Cucci