[issue32703] 'async with' somehow suppresses unawaited coroutine warnings

Change by Xavier G. Domingo : -- nosy: +xgdomingo ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail

[issue32703] 'async with' somehow suppresses unawaited coroutine warnings

Yury Selivanov added the comment: Merged; closing this issue. -- resolution: -> fixed stage: patch review -> resolved status: open -> closed ___ Python tracker ___ ___

[issue32703] 'async with' somehow suppresses unawaited coroutine warnings

Yury Selivanov added the comment: New changeset 2a2270db9be9bdac5ffd2d50929bf905e7391a06 by Yury Selivanov in branch 'master': bpo-32703: Fix coroutine resource warning in case where there's an error (GH-5410) https://github.com/python/cpython/commit/2a2270db9be9bdac5ffd2d50929bf905e7391a06

[issue32703] 'async with' somehow suppresses unawaited coroutine warnings

Yury Selivanov added the comment: I knew about that "if", but it never fully registered to me why it's there and what it is protecting us from ;) So I had to debug half of ceval loop before I stumbled upon it again ;) -- ___ Python tracker

[issue32703] 'async with' somehow suppresses unawaited coroutine warnings

Nick Coghlan added the comment: Ah, and in my REPL example, the NameError was pending when the internal result storage was getting set back to None. I'm not sure I even knew the "Don't complain when an exception is pending" check existed, so it would have taken me a long time to find that. -

[issue32703] 'async with' somehow suppresses unawaited coroutine warnings

Nathaniel Smith added the comment: Well, I feel silly then: bpo-32605 -- ___ Python tracker ___ ___ Python-bugs-list mailing list Un

[issue32703] 'async with' somehow suppresses unawaited coroutine warnings

Yury Selivanov added the comment: So the problem was that _PyGen_Finalize wasn't issuing any warnings if there's any error set in the current tstate. And in Nathaniel's case, the current error was an AttributeError('__aexit__'). This check is weird, because right before raising the warning,

[issue32703] 'async with' somehow suppresses unawaited coroutine warnings

Change by Yury Selivanov : -- keywords: +patch pull_requests: +5243 stage: -> patch review ___ Python tracker ___ ___ Python-bugs-li

[issue32703] 'async with' somehow suppresses unawaited coroutine warnings

Yury Selivanov added the comment: Ah, we should never really get to WITH_CLEANUP_START; the exception should be raised in BEFORE_ASYNC_WITH -- ___ Python tracker ___ _

[issue32703] 'async with' somehow suppresses unawaited coroutine warnings

Yury Selivanov added the comment: So refactoring it into "c = open_file(); async with c" just prolongs the life of the coroutine so that it's GCed outside of WITH_CLEANUP_START/WITH_CLEANUP_FINISH block. Something weird is going on in that block. --

[issue32703] 'async with' somehow suppresses unawaited coroutine warnings

Yury Selivanov added the comment: The difference between these two functions is two extra opcodes: STORE_FAST/LOAD_FAST before BEFORE_ASYNC_WITH. With them we have a warning. -- ___ Python tracker _

[issue32703] 'async with' somehow suppresses unawaited coroutine warnings

Yury Selivanov added the comment: Changing async def main(): async with open_file(): pass to async def main(): c = open_file() async with c: pass also makes it print the warning :) Also I've made a test out of this snippet and running tests in refleak mode shows

[issue32703] 'async with' somehow suppresses unawaited coroutine warnings

Nick Coghlan added the comment: Looking at the ceval code, I think Yury's theory is plausible, and we may also be leaving the interpreter's internal stack in a dubious state. Things then get cleaned up if you wrap the async with in a try/except or try/finally: == >>> async def try

[issue32703] 'async with' somehow suppresses unawaited coroutine warnings

Change by Yury Selivanov : -- components: +Interpreter Core -asyncio nosy: +ncoghlan ___ Python tracker ___ ___ Python-bugs-list mail

[issue32703] 'async with' somehow suppresses unawaited coroutine warnings

Nathaniel Smith added the comment: > Yury's theory: maybe BEFORE_ASYNC_WITH's error-handling path is forgetting to > DECREF the object. Nope, that doesn't seem to be it. This version prints "refcount: 2" twice, *and* prints a proper "was never awaited" warning: - import sys async def o

[issue32703] 'async with' somehow suppresses unawaited coroutine warnings

New submission from Nathaniel Smith : Example (minimal version of https://github.com/python-trio/trio/issues/425): - async def open_file(): pass async def main(): async with open_file(): # Should be 'async with await open_file()' pass coro = main() coro.send(None) -