Syntax error in generated stub when using dataclass

[bramstroker]

Bug Report

Stubgen generates an output file with a syntax error.
It generates def __mypy-replace which is invalid python syntax because of the dash.

To Reproduce

With the following python code, generate a stub including the --include-private flag.

stubgen --include-private test.py

from dataclasses import dataclass

@dataclass
class MyDataClass:
    foo: str
    bar: int

Expected Behavior

The stub is generated without syntax errors.

Actual Behavior

A syntax error is raised when parsing the file:

  File "out/test.pyi", line 5
    def __mypy-replace(*, foo, bar) -> None: ...
              ^
SyntaxError: invalid syntax

When I generate the file without --include-private than the stub is generated correctly.

Your Environment

• Mypy version used: 1.5.1
• Python version used: 3.11.4

Extra info

Also see KapJI/homeassistant-stubs#349 where this issue was raised.
These stubs are used in custom Home Assistant components, and currently this is broken.

[JelleZijlstra]

cf. #15689 which fixed a similar bug in stubtest

[hamdanal]

cf. #15689 which fixed a similar bug in stubtest

This is also fixed by #15625 which is functional but still waiting on an answer on how to test a dataclass with a _: dataclasses.KW_ONLY field on pythons <3.10