Line Breaks on long class member names

[timozerrer]

Describe the bug

Black does not break lines containing class member access even though character line limit is exceeded.

To Reproduce

Given this code using dataclasses with long member names:

from dataclasses import dataclass


@dataclass
class SomeNestedDataclass:
    very_long_nested_dataclass_variable_name: str


@dataclass
class SomeDataclass:
    long_dataclass_variable_name: SomeNestedDataclass


def some_func(some_datclass_param):
    pass


some_dataclass = SomeDataclass(
    long_dataclass_variable_name=SomeNestedDataclass(
        very_long_nested_dataclass_variable_name="VeryLongString"
    )
)
some_func(
    some_datclass_param=some_dataclass.long_dataclass_variable_name.very_long_nested_dataclass_variable_name
)

Black removes line breaks if I insert them myself (See expected behaviour section).

Running black formatter with explicit line length:

 python3.8 -m black test_line_lenght.py --line-length 88                                                     
All done! ✨ 🍰 ✨
1 file left unchanged.

Pylint reports line exceeding length:

python3.8 -m pylint test_line_lenght.py --disable=missing-module-docstring,missing-function-docstring,unused-argument,missing-function-docstring,invalid-name,missing-class-docstring
************* Module test_line_lengh
test_line_lenght.py:24:0: C0301: Line too long (108/88) (line-too-long)

------------------------------------------------------------------
Your code has been rated at 8.89/10 (previous run: 8.89/10, +0.00)

Expected behavior

Black should insert line break on line exceeding 88 characters. My interpretation it should look like this based on PEP8:

some_func(
    some_datclass_param=some_dataclass.long_dataclass_variable_name.
    very_long_nested_dataclass_variable_name
)

If manually applying this refactoring, black will revert so this assignment is a one-liner again.

Environment

• Black's version: 22.10.0
• OS and Python version:

Additional context Similar issue on line breaks #1802 recommends using --experimental-string-processing which does not solve this issue.

I frequently use nested dataclasses in my projects and i run into this issue every now and then because pylint reports line-too-long errors.

[JelleZijlstra]

The last case is a duplicate of #510 (attribute chains). You mention various other cases, but those should get specific issues in the https://github.com/psf/black/labels/F%3A%20linetoolong label.