Crash when defining __post_init__ outside the base-level of a class

[tjkuson]

Crash Report

Defining a function named __post_init__ anywhere that isn't a class base-level crashes mypy.

Traceback

lmao.py:1: error: INTERNAL ERROR -- Please try using mypy master on GitHub:
https://mypy.readthedocs.io/en/stable/common_issues.html#using-a-development-mypy-build
Please report a bug at https://github.com/python/mypy/issues
version: 1.6.1
Traceback (most recent call last):
  File "mypy/checker.py", line 585, in accept
  File "mypy/nodes.py", line 790, in accept
  File "mypy/checker.py", line 994, in visit_func_def
  File "mypy/checker.py", line 998, in _visit_func_def
  File "mypy/checker.py", line 1081, in check_func_item
  File "mypy/plugins/dataclasses.py", line 1091, in is_processed_dataclass
AttributeError: attribute 'metadata' of 'TypeInfo' undefined
lmao.py:1: : note: use --pdb to drop into pdb

To Reproduce

Top-level:

def __post_init__(): ...

Nested:

class Foo:
    def func(self):
        def __post_init__(): ...

The following does not cause mypy to crash:

__post_init__ = lambda _: ...

Nor does

class Foo:
    def __post_init__(): ...

Your Environment

• mypy version used: 1.61
• Python version used: Reproduced on 3.9 and 3.11
• Operating system and version: macOS Sonoma 14.1

[AlexWaygood]

This reproduces with mypy 1.6.1, but is already fixed on the mypy master branch. The fix will be included with mypy 1.7, which should be released soon (see #16341)

[AlexWaygood]

(See #16057 and #16080 for the previous issue/PR for regarding this bug :)

[tjkuson]

Thanks for the quick response! Apologies for missing the previous issue.