Black: Black fails with "AST error message: invalid syntax" if using the walrus operator in parenthesis

[brmc]

Describe the bug Black cannot format code that uses the walrus operator, := , in parentheses

To Reproduce Steps to reproduce the behavior:

1. Take this file:

if (blah := 4):
    print(666)

1. Run _Black_ (v19.10b0) on it with default arguments
2. It should produce the following error: error: cannot format example.py: cannot use --safe with this file; failed to parse source file. AST error message: invalid syntax (<unknown>, line 1)

Expected behavior It should format the file and not throw an error

Environment (please complete the following information):

• Version: 19.10b0
• OS and Python version: Linux Mint 19.3, python 3.8.0

Does this bug also happen on master? No

[zsol]

I can't repro this either locally or on https://black.now.sh so there's something likely with your environment. I would check what version of python Black is running with. You'd get this message if you're running it with something <3.8

[crmocz]

I can't reproduce this either. Tested with black 19.10b0 on Mint 19 and Python 3.8.1

✗ cat 1262.py
if (blah := 4):
print(666)

✗ black .
reformatted 1262.py
All done! ✨ 🍰 ✨
1 file reformatted, 17 files left unchanged.

✗ cat 1262.py
if (blah := 4) :
print(666)