[Python-checkins] gh-87822: Make traceback module robust to exceptions from repr() of local values (GH-94691)

Mon Jul 11 05:14:58 EDT 2022

https://github.com/python/cpython/commit/46fc584b00f2ccee5b77d8fc525881def8670a02
commit: 46fc584b00f2ccee5b77d8fc525881def8670a02
branch: main
author: Simon-Martin Schröder <martin.schroeder at nerdluecht.de>
committer: iritkatriel <1055913+iritkatriel at users.noreply.github.com>
date: 2022年07月11日T10:14:15+01:00
summary:
gh-87822: Make traceback module robust to exceptions from repr() of local values (GH-94691)
files:
A Misc/NEWS.d/next/Library/2022-07-08-17-49-12.gh-issue-87822.F9dzkf.rst
M Doc/library/traceback.rst
M Lib/test/test_traceback.py
M Lib/traceback.py
M Misc/ACKS

diff --git a/Doc/library/traceback.rst b/Doc/library/traceback.rst
index a8412cc93d16f..8cb6af9bc840b 100644
--- a/Doc/library/traceback.rst
+++ b/Doc/library/traceback.rst
@@ -341,6 +341,10 @@ capture data for later printing in a lightweight fashion.
 local variables in each :class:`FrameSummary` are captured as object
 representations.
 
+ .. versionchanged:: 3.12
+ Exceptions raised from :func:`repr` on a local variable (when
+ *capture_locals* is ``True``) are no longer propagated to the caller.
+
 .. classmethod:: from_list(a_list)
 
 Construct a :class:`StackSummary` object from a supplied list of
diff --git a/Lib/test/test_traceback.py b/Lib/test/test_traceback.py
index f4161fbf0178d..602bd2cae0a96 100644
--- a/Lib/test/test_traceback.py
+++ b/Lib/test/test_traceback.py
@@ -2279,6 +2279,9 @@ def format_frame_summary(self, frame_summary):
 f' File "{__file__}", line {lno}, in f\n 1/0\n'
 )
 
+class Unrepresentable:
+ def __repr__(self) -> str:
+ raise Exception("Unrepresentable")
 
 class TestTracebackException(unittest.TestCase):
 
@@ -2546,12 +2549,13 @@ def test_locals(self):
 linecache.updatecache('/foo.py', globals())
 e = Exception("uh oh")
 c = test_code('/foo.py', 'method')
- f = test_frame(c, globals(), {'something': 1, 'other': 'string'})
+ f = test_frame(c, globals(), {'something': 1, 'other': 'string', 'unrepresentable': Unrepresentable()})
 tb = test_tb(f, 6, None, 0)
 exc = traceback.TracebackException(
 Exception, e, tb, capture_locals=True)
 self.assertEqual(
- exc.stack[0].locals, {'something': '1', 'other': "'string'"})
+ exc.stack[0].locals,
+ {'something': '1', 'other': "'string'", 'unrepresentable': '<local repr() failed>'})
 
 def test_no_locals(self):
 linecache.updatecache('/foo.py', globals())
diff --git a/Lib/traceback.py b/Lib/traceback.py
index 55f8080044053..b1a5fd0a26d40 100644
--- a/Lib/traceback.py
+++ b/Lib/traceback.py
@@ -279,7 +279,8 @@ def __init__(self, filename, lineno, name, *, lookup_line=True,
 self._line = line
 if lookup_line:
 self.line
- self.locals = {k: repr(v) for k, v in locals.items()} if locals else None
+ self.locals = {k: _safe_string(v, 'local', func=repr)
+ for k, v in locals.items()} if locals else None
 self.end_lineno = end_lineno
 self.colno = colno
 self.end_colno = end_colno
diff --git a/Misc/ACKS b/Misc/ACKS
index b6340414cf701..32475f874c36d 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1590,6 +1590,7 @@ Ed Schouten
 Scott Schram
 Robin Schreiber
 Chad J. Schroeder
+Simon-Martin Schroeder
 Christian Schubert
 Sam Schulenburg
 Andreas Schwab
diff --git a/Misc/NEWS.d/next/Library/2022-07-08-17-49-12.gh-issue-87822.F9dzkf.rst b/Misc/NEWS.d/next/Library/2022-07-08-17-49-12.gh-issue-87822.F9dzkf.rst
new file mode 100644
index 0000000000000..7b27f5df45ba2
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-07-08-17-49-12.gh-issue-87822.F9dzkf.rst
@@ -0,0 +1 @@
+When called with ``capture_locals=True``, the :mod:`traceback` module functions swallow exceptions raised from calls to ``repr()`` on local variables of frames. This is in order to prioritize the original exception over rendering errors. An indication of the failure is printed in place of the missing value. (Patch by Simon-Martin Schroeder).
