Remove binding of captured exceptions when not used to reduce the chances of creating cycles (GH-17246)
Capturing exceptions into names can lead to reference cycles though the __traceback__ attribute of the exceptions in some obscure cases that have been reported previously and fixed individually. As these variables are not used anyway, we can remove the binding to reduce the chances of creating reference cycles.
See for example GH-13135
diff --git a/Lib/test/test_traceback.py b/Lib/test/test_traceback.py
index 72dc7af..7135d99 100644
--- a/Lib/test/test_traceback.py
+++ b/Lib/test/test_traceback.py
@@ -313,7 +313,7 @@
with captured_output("stderr") as stderr_f:
try:
f()
- except RecursionError as exc:
+ except RecursionError:
render_exc()
else:
self.fail("no recursion occurred")
@@ -360,7 +360,7 @@
with captured_output("stderr") as stderr_g:
try:
g()
- except ValueError as exc:
+ except ValueError:
render_exc()
else:
self.fail("no value error was raised")
@@ -396,7 +396,7 @@
with captured_output("stderr") as stderr_h:
try:
h()
- except ValueError as exc:
+ except ValueError:
render_exc()
else:
self.fail("no value error was raised")
@@ -424,7 +424,7 @@
with captured_output("stderr") as stderr_g:
try:
g(traceback._RECURSIVE_CUTOFF)
- except ValueError as exc:
+ except ValueError:
render_exc()
else:
self.fail("no error raised")
@@ -452,7 +452,7 @@
with captured_output("stderr") as stderr_g:
try:
g(traceback._RECURSIVE_CUTOFF + 1)
- except ValueError as exc:
+ except ValueError:
render_exc()
else:
self.fail("no error raised")