Complex decorators break safe mode

[emfdavid]

Using decorator syntax with a chained function call breaks the AST validation in safe mode.
This is a pattern for prometheus client

Use black playground repro case

If I comment out the chained labels - it works.

Currently my best work around is to ignore the files using this syntax in my config and run black manually with fast for those files.

[JelleZijlstra]

We may never have properly added support for https://www.python.org/dev/peps/pep-0614/.

[isidentical]

AFAIK the PEP 614 support is there:

black/src/blib2to3/Grammar.txt

Line 15 in 98db4ab

decorator: '@' namedexpr_test NEWLINE

This seems like a problem with Black Playground, since they are still using Python 3.8. Created jpadilla/black-playground#53

@emfdavid what is the version of the python interpreter you are running the black with?

[emfdavid]

Excellent catch @isidentical
I set our commit hook to use py37 as the lowest level supported and didn't think twice about it when I could repro the issue in playground.
Are issues with ast validation rare enough that it would be helpful to add try checking your python version? to the error message?

[JelleZijlstra]

@emfdavid good idea, do you want to submit a PR?

[isidentical]

Are issues with ast validation rare enough that it would be helpful to add try checking your python version? to the error message?

I would assume if people are using the newer syntax, their python version would be higher. Though in case of pre-commit, it might go unnoticed considering it is using a separate environment. So I think it makes sense.

[isidentical]

This has been now fixed on the playground as well!

[emfdavid]

@JelleZijlstra #2786