bpo-44594: fix (Async)ExitStack handling of __context__ (gh-27089)

* bpo-44594: fix (Async)ExitStack handling of __context__

Make enter_context(foo()) / enter_async_context(foo()) equivalent to
`[async] with foo()` regarding __context__ when an exception is raised.

Previously exceptions would be caught and re-raised with the wrong
context when explicitly overriding __context__ with None.
This commit is contained in:
John Belmonte 2021-10-04 15:49:55 +09:00 committed by GitHub
parent a25dcaefb7
commit e6d1aa1ac6
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4 changed files with 76 additions and 4 deletions

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@ -553,10 +553,10 @@ class ExitStack(_BaseExitStack, AbstractContextManager):
# Context may not be correct, so find the end of the chain
while 1:
exc_context = new_exc.__context__
if exc_context is old_exc:
if exc_context is None or exc_context is old_exc:
# Context is already set correctly (see issue 20317)
return
if exc_context is None or exc_context is frame_exc:
if exc_context is frame_exc:
break
new_exc = exc_context
# Change the end of the chain to point to the exception
@ -693,10 +693,10 @@ class AsyncExitStack(_BaseExitStack, AbstractAsyncContextManager):
# Context may not be correct, so find the end of the chain
while 1:
exc_context = new_exc.__context__
if exc_context is old_exc:
if exc_context is None or exc_context is old_exc:
# Context is already set correctly (see issue 20317)
return
if exc_context is None or exc_context is frame_exc:
if exc_context is frame_exc:
break
new_exc = exc_context
# Change the end of the chain to point to the exception