INTERNAL ERROR on mismatched # fmt comments

[inglesp]

Describe the bug INTERNAL ERROR on mismatched # fmt comments

To Reproduce Steps to reproduce the behavior:

Run black over a file containing mismatched # fmt comments inside functions.

$ cat bad.py 
def f1():
    pass
    # fmt: off
    # fmt: off


def f2():
    pass
    # fmt: off
    # fmt: on

$ black bad.py
error: cannot format bad.py: INTERNAL ERROR: Black produced code that is not equivalent to the source.  Please report a bug on https://github.com/psf/black/issues.  This diff might be helpful: /var/folders/fm/_0l2_jwj0cs6mz43zdq91gfw0000gn/T/blk_62sexy11.log
Oh no! 💥 💔 💥
1 file failed to reformat.

Expected behavior Black should not crash, and should point out the mismatched # fmt comments.

Environment (please complete the following information):

• Version: 19.10b0
• OS and Python version: OSX/Python 3.8.0

Does this bug also happen on master? To answer this, you have two options:

Yes, with 19.10b1.dev48+g959848c on my machine.

But with the online formatter (running 959848c) it doesn't crash, but produces something incorrect:

def f1():
    pass
    # fmt: off
    # fmt: off

    def f2():
        pass
        # fmt: off
        # fmt: on

Additional context I have attached the debug output.

blk_62sexy11.log

[ichard26]

The behaviour seen here signals that this is a duplicate of #569. If you move the formatting control comments to the global scope, Black won't produce bad code.

(black-rHKUX7ap) R:\Programming\black>type test.py
# fmt: off
# fmt: off
some_var = [1, 3,
 3 ,124 , 125]

def foo(): pass

def baz():
    return "I'm baz!"

# fmt: off
# fmt: on

def bar():
    raise NotImplementedError("It's a test function duh!")

another_misformatted_var = ('hello world', [1, 2
], 53,
"placeholder text")

(black-rHKUX7ap) R:\Programming\black>black test.py --diff --color
--- test.py     2020-08-04 00:25:30.870797 +0000
+++ test.py     2020-08-04 00:28:10.698073 +0000
@@ -9,11 +9,11 @@
     return "I'm baz!"

 # fmt: off
 # fmt: on

+
 def bar():
     raise NotImplementedError("It's a test function duh!")

-another_misformatted_var = ('hello world', [1, 2
-], 53,
-"placeholder text")
+
+another_misformatted_var = ("hello world", [1, 2], 53, "placeholder text")
would reformat test.py
All done! ✨ 🍰 ✨
1 file would be reformatted.

Thanks for filing this bug report!

Side-note: if someone else is interested having Black notice and warn about mismatched formatting control comments, please file a new (enhancement) issue.

---

Environment:

• Black version: master (b59a524)
• Python version: CPython 3.8.1
• OS version: Windows 10 Home Build 18383