Error on some assignment expressions

[dmyersturnbull]

Black seems to break on some assignment expressions.

This works fine:

if (version := get_version()) is not None:

This breaks:

if (version := get_version() is not None):

It should either do nothing or remove parentheses as per #1656.

• Version: master head as of 2020-01-01 (f07832e)
• OS and Python version: Windows, Python 3.9.1 (virtualenv inside Miniconda env)

[ichard26]

Thanks for the bug report! Unforutunately I can't reproduce the bug you're describing using the Black Playground and locally with CPython 3.8.5 and Ubuntu 20.04.01 LTS installed:

(black) ichard26@acer-ubuntu:~/programming/oss/black$ git log -n1
commit f07832eac44eb38f8b048aae3e1de3512a06057c (HEAD -> main, upstream/master)
Author: Paul "TBBle" Hampson <[email protected]>
Date:   Sat Jan 2 05:54:35 2021 +1100

    Use Prettier pre-commit mirror (#1896)
    
    This fixes Prettier install failures similar to those seen in
    https://github.com/prettier/prettier/issues/9459, and is the solution
    recommended there.
    
    Signed-off-by: Paul "TBBle" Hampson <[email protected]>
(black) ichard26@acer-ubuntu:~/programming/oss/black$ echo "if (version := get_version() is not None):
    pass" > test.py
(black) ichard26@acer-ubuntu:~/programming/oss/black$ black test.py --diff --check --color
All done! ✨ 🍰 ✨
1 file would be left unchanged.

I also tested in a CPython 3.9.1 virtualenv and still no error.

By any chance were you getting black produced different code on the second pass of the formatter errors? If yes, then I'm guessing you were hitting #1588 which is fixed on master although the fix hasn't been shipped in any release. If not, what error? The other two options are 1. black produced invalid code errors, OR 2. uncaught exceptions.

[dmyersturnbull]

@ichard26 Yes, I am seeing that. (I should have pasted the error message!)

Assuming #1588 is the underlying issue, I'll go ahead and close this.