async for statement is not a syntax error in sync context

[zsol]

BPO	33363
Nosy	@ned-deily, @njsmith, @1st1, @zsol
PRs	bpo-33363: raise SyntaxError for async for/with outside async functions #6616 [3.7] bpo-33363: raise SyntaxError for async for/with outside async functions (GH-6616). #6619

^{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 2018-04-27.22:34:03.590>
created_at = <Date 2018-04-26.05:18:50.185>
labels = ['interpreter-core', '3.8', 'type-bug', '3.7', 'release-blocker']
title = 'async for statement is not a syntax error in sync context'
updated_at = <Date 2018-04-27.22:34:03.589>
user = 'https://github.com/zsol'

bugs.python.org fields:

activity = <Date 2018-04-27.22:34:03.589>
actor = 'yselivanov'
assignee = 'none'
closed = True
closed_date = <Date 2018-04-27.22:34:03.590>
closer = 'yselivanov'
components = ['Interpreter Core']
creation = <Date 2018-04-26.05:18:50.185>
creator = 'zsol'
dependencies = []
files = []
hgrepos = []
issue_num = 33363
keywords = ['patch']
message_count = 6.0
messages = ['315775', '315776', '315777', '315847', '315859', '315860']
nosy_count = 4.0
nosy_names = ['ned.deily', 'njs', 'yselivanov', 'zsol']
pr_nums = ['6616', '6619']
priority = 'release blocker'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue33363'
versions = ['Python 3.7', 'Python 3.8']

[zsol]

Since 3.7, async generators can be used in non-async functions. The way this is implemented allows the following to be valid syntax:

def f():
    async for i in aiterable:
        pass
    return 1

The return value of the above function is a Future that will never be done().

[1st1]

Wow, this is a regression that has to be fixed in 3.7.

[njsmith]

Sorry, not sure why bpo decided to reset the priority there.

[1st1]

New changeset e239650 by Yury Selivanov (Zsolt Dollenstein) in branch 'master':
bpo-33363: raise SyntaxError for async for/with outside async functions (bpo-6616)
e239650

[1st1]

New changeset a93a663 by Yury Selivanov (Zsolt Dollenstein) in branch '3.7':
[3.7] bpo-33363: raise SyntaxError for async for/with outside async functions (GH-6616). (GH-6619)
a93a663

[1st1]

Thanks so much!