Empty line and `...` and "unindent does not match any outer indentation level"

[Azureblade3808]

Describe the bug

If the first line inside an indented function is empty and the body is ..., black fails to format it.

To Reproduce
https://black.vercel.app/?version=main&state=_Td6WFoAAATm1rRGAgAhARYAAAB0L-Wj4ACQAFxdAD2IimZxl1N_WlXnON2nzNJyA7rxEz3ITq0Rr8lcyuT-7lJq6-30yBPNldub44lXXOBKYonCShOJuW7cuZ_9TCCgKPjpZqqogwanJNRK0YrZc4gHqvyNL22TtygAACOiGQzKhfHyAAF4kQEAAAC0Mv5wscRn-wIAAAAABFla

class C:
    def f(self):

        ...

Expected behavior

The snippet above can be formatted.

Environment

• Black's version: Stable: 24.1.0 | Main: @ed770b
• OS and Python version: irrelevant

Additional context

None.

Edit

Function body being ... is a key condition.

[JelleZijlstra]

Confirmed:

% black -c '''class C:
    def f(self):

        ...
'''
class C:
    def f(self):

        ...
error: cannot format <string>: unindent does not match any outer indentation level (<tokenize>, line 5)

Black should instead format this as:

class C:
    def f(self): ...

[harvinmumick]

Hi, my friend, @peterkra25 , and I are two students from the University of Michigan enrolled in a software engineering class (EECS 481), and our final project is to contribute to an open-source Github project. We came across Black and saw this issue, and reached out to @JelleZijlstra regarding this. We're looking into this issue and will try to resolve it over the next few weeks.

[JelleZijlstra]

One more thought: I haven't looked at the code, but I suspect the changes in #3796 are closely related to this bug, so looking at the code affected by that change will be a good way to start finding the location of the bug.

[hauntsaninja]

Thank you for resolving this issue!