Close #14969: Improve the handling of exception chaining in contextlib.ExitStack
diff --git a/Lib/contextlib.py b/Lib/contextlib.py
index f5232b6..bde2feb 100644
--- a/Lib/contextlib.py
+++ b/Lib/contextlib.py
@@ -225,6 +225,17 @@
return self
def __exit__(self, *exc_details):
+ # We manipulate the exception state so it behaves as though
+ # we were actually nesting multiple with statements
+ frame_exc = sys.exc_info()[1]
+ def _fix_exception_context(new_exc, old_exc):
+ while 1:
+ exc_context = new_exc.__context__
+ if exc_context in (None, frame_exc):
+ break
+ new_exc = exc_context
+ new_exc.__context__ = old_exc
+
# Callbacks are invoked in LIFO order to match the behaviour of
# nested context managers
suppressed_exc = False
@@ -236,9 +247,8 @@
exc_details = (None, None, None)
except:
new_exc_details = sys.exc_info()
- if exc_details != (None, None, None):
- # simulate the stack of exceptions by setting the context
- new_exc_details[1].__context__ = exc_details[1]
+ # simulate the stack of exceptions by setting the context
+ _fix_exception_context(new_exc_details[1], exc_details[1])
if not self._exit_callbacks:
raise
exc_details = new_exc_details