Crash in string annotations in lambda with keyword-only argument without default value

[serhiy-storchaka]

BPO	34854
Nosy	@gvanrossum, @ambv, @serhiy-storchaka, @miss-islington
PRs	bpo-34854: Fix a crash in string annotations containing specific lambda. #9645 [3.7] bpo-34854: Fix compiling string annotations containing lambdas. (GH-9645) #9646

^{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 2018-09-30.18:33:39.148>
created_at = <Date 2018-09-30.16:25:00.255>
labels = ['interpreter-core', '3.7', '3.8', 'type-crash']
title = 'Crash in string annotations in lambda with keyword-only argument without default value'
updated_at = <Date 2018-09-30.18:41:05.594>
user = 'https://github.com/serhiy-storchaka'

bugs.python.org fields:

activity = <Date 2018-09-30.18:41:05.594>
actor = 'gvanrossum'
assignee = 'none'
closed = True
closed_date = <Date 2018-09-30.18:33:39.148>
closer = 'serhiy.storchaka'
components = ['Interpreter Core']
creation = <Date 2018-09-30.16:25:00.255>
creator = 'serhiy.storchaka'
dependencies = []
files = []
hgrepos = []
issue_num = 34854
keywords = ['patch']
message_count = 5.0
messages = ['326730', '326737', '326739', '326742', '326743']
nosy_count = 4.0
nosy_names = ['gvanrossum', 'lukasz.langa', 'serhiy.storchaka', 'miss-islington']
pr_nums = ['9645', '9646']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'crash'
url = 'https://bugs.python.org/issue34854'
versions = ['Python 3.7', 'Python 3.8']

[serhiy-storchaka]

Compiling a string annotation containing a lambda with keyword-only argument without default value causes a crash.

from __future__ import annotations
def f() -> (lambda *, x: x): pass

The following PR fixes this crash. It also fixes other errors:

• Removes a space between "lambda" and ":" in the representation of lambda without argument.

• Removes the final "*" (it is incorrect syntax) in the representation of lambda without *args and keyword-only arguments when compile from AST.

[serhiy-storchaka]

New changeset 2a2940e by Serhiy Storchaka in branch 'master':
bpo-34854: Fix compiling string annotations containing lambdas. (GH-9645)
2a2940e

[miss-islington]

New changeset 0f161b3 by Miss Islington (bot) in branch '3.7':
bpo-34854: Fix compiling string annotations containing lambdas. (GH-9645)
0f161b3

[serhiy-storchaka]

These bugs was found when working on bpo-34856.

[gvanrossum]

Should go to @ambv.

On Sun, Sep 30, 2018 at 9:29 AM Serhiy Storchaka <report@bugs.python.org>
wrote:

Change by Serhiy Storchaka <storchaka+cpython@gmail.com>:

----------
keywords: +patch
pull_requests: +9037
stage: -> patch review

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Python tracker <report@bugs.python.org>
<https://bugs.python.org/issue34854\>

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