Minimal file produces invalid code

[codyd51]

Describe the bug Under certain circumstances, annotating a method with # yapf: disable among other inputs causes black to produce invalid code.

To Reproduce Steps to reproduce the behavior:

Minimal reproducing input:

class BaseClass1:
    # yapf: disable
    def method1(self):
        pass


class BaseClass2:
    # yapf: disable
    def method2(self):
        pass


class Mixin(BaseClass1, BaseClass2):
    pass

$ black bad_input.py
error: cannot format bad_input.py: INTERNAL ERROR: Black produced invalid code: expected an indented block (<unknown>, line 8). Please report a bug on https://github.com/ambv/black/issues.  This invalid output might be helpful: /var/folders/y0/clprvktj3b5__hkvm2p4m_yr0000gn/T/blk_8rbcsejt.log
All done! 💥 💔 💥
1 file failed to reformat.

Here's the associated logfile: blk_8rbcsejt.log

Expected behavior The file is reformatted while preserving code structure.

Environment (please complete the following information):

• Version: Tested against master and 19.3b0
• OS and Python version: macOS Catalina 10.15.3 Beta / Python 3.7.7

Does this bug also happen on master? Yes. I tested the sample file with https://black.now.sh/?version=master.

[greschd]

I've just encountered the same issue, with black==20.8b0, Python 3.7.9, Ubuntu 18.04.

To add some observations, here's another reproducing example:

def foo():
    # yapf: disable
    pass

1

It appears the error is that indentation is wrong after the reformatting: This is the result from black --fast:

def foo():
    # yapf: disable
    pass

    1

[ichard26]

Duplicate of #569. # yapf: enable/disable are aliases to Black's own # fmt: off/on.