@asynccontextmanager doesn't work well with async generators

[ValentinLavrinenko]

BPO	33786
Nosy	@ncoghlan, @ned-deily, @asvetlov, @ambv, @1st1, @miss-islington, @oremanj
PRs	bpo-33786: Fix asynchronous generators to handle GeneratorExit in athrow() #7467 [3.7] bpo-33786: Fix asynchronous generators to handle GeneratorExit in athrow() (GH-7467) #7506 [3.6] bpo-33786: Fix asynchronous generators to handle GeneratorExit in athrow() #7507 bpo-33786: Fix asynchronous generators to handle GeneratorExit in athrow() #7514 [3.7] bpo-33786: Fix asynchronous generators to handle GeneratorExit in athrow() (GH-7467) #21878

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2020-08-14.09:53:24.162>
created_at = <Date 2018-06-06.17:24:35.200>
labels = ['interpreter-core', '3.8', 'type-bug', '3.7']
title = "@asynccontextmanager doesn't work well with async generators"
updated_at = <Date 2020-08-14.09:54:49.933>
user = 'https://bugs.python.org/ValentinLavrinenko'

bugs.python.org fields:

activity = <Date 2020-08-14.09:54:49.933>
actor = 'asvetlov'
assignee = 'none'
closed = True
closed_date = <Date 2020-08-14.09:53:24.162>
closer = 'ned.deily'
components = ['Interpreter Core']
creation = <Date 2018-06-06.17:24:35.200>
creator = 'Valentin Lavrinenko'
dependencies = []
files = []
hgrepos = []
issue_num = 33786
keywords = ['patch']
message_count = 12.0
messages = ['318853', '318854', '318882', '318967', '318998', '319005', '319012', '375189', '375219', '375388', '375389', '375390']
nosy_count = 8.0
nosy_names = ['ncoghlan', 'ned.deily', 'asvetlov', 'lukasz.langa', 'yselivanov', 'miss-islington', 'Valentin Lavrinenko', 'Joshua Oreman']
pr_nums = ['7467', '7506', '7507', '7514', '21878']
priority = None
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue33786'
versions = ['Python 3.6', 'Python 3.7', 'Python 3.8']

[ValentinLavrinenko]

@asynccontextmanager
async def ctx():
    yield


async def gen():
    async with ctx():
        yield 'hello'
        yield 'world'


async def main():
    async with ctx():
        async for value in gen():
            print(value)
            raise RuntimeError()

Running main() leads to RuntimeError: generator didn't stop after throw(). This happens because async gernerator's .athrow() method doesn't re-throw GeneratorExit exception; probably, this is wrong.

[ValentinLavrinenko]

Sorry, async with ctx() in main() is not needed.

[1st1]

Would be nice to fix this in 3.7.0

[ned-deily]

Would be nice to fix this in 3.7.0

Please do!

[1st1]

New changeset 52698c7 by Yury Selivanov in branch 'master':
bpo-33786: Fix asynchronous generators to handle GeneratorExit in athrow() (GH-7467)
52698c7

[1st1]

New changeset 8de73d5 by Yury Selivanov in branch '3.6':
bpo-33786: Fix asynchronous generators to handle GeneratorExit in athrow() (GH-7467) (GH-7507)
8de73d5

[1st1]

New changeset b0bb9a8 by Yury Selivanov in branch '3.6':
bpo-33786: Fix asynchronous generators to handle GeneratorExit in athrow() (GH-7467) (bpo-7514)
b0bb9a8