TypeError: __init__() missing required argument 'default' (pos 6)

[romulorosa]

Crash Report
I tried to run mypy --show-traceback since it is breaking on version 1.4.0 (I was using version 1.3.0 before)
(Tell us what happened.)

Traceback

Traceback (most recent call last):
  File "mypy/semanal.py", line 6451, in accept
  File "mypy/nodes.py", line 1139, in accept
  File "mypy/semanal.py", line 1582, in visit_class_def
  File "mypy/semanal.py", line 1667, in analyze_class
  File "mypy/semanal.py", line 1694, in analyze_class_body_common
  File "mypy/semanal.py", line 1777, in apply_class_plugin_hooks
  File "pydantic/mypy.py", line 129, in pydantic.mypy.PydanticPlugin._pydantic_model_class_maker_callback
  File "pydantic/mypy.py", line 262, in pydantic.mypy.PydanticModelTransformer.transform
  File "pydantic/mypy.py", line 441, in pydantic.mypy.PydanticModelTransformer.add_construct_method
TypeError: __init__() missing required argument 'default' (pos 6)

/Users/rrosa/env/lib/python3.11/site-packages/pydantic/env_settings.py:22: 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: 1.4.0
/Users/rrosa/env/lib/python3.11/site-packages/pydantic/env_settings.py:22: : note: use --pdb to drop into pdb

To Reproduce

(Write what you did to reproduce the crash. Full source code is
appreciated. We also very much appreciate it if you try to narrow the
source down to a small stand-alone example.)

Your Environment

• Mypy version used: 1.4.0
• Mypy command-line flags: mypy
• Mypy configuration options from mypy.ini (and other config files):

[mypy]
python_version = 3.11
files = my_project/**/*.py
plugins = pydantic.mypy
disallow_untyped_defs = true
warn_no_return = false
ignore_missing_imports = true

• Python version used: 3.11.3
• Operating system and version: MacOS Ventura 13.4 (M1 Pro)

[AlexWaygood]

The traceback indicates that this is an issue in pydantic's mypy plugin rather than mypy itself.

Are you using the latest version of pydantic? If not, does it still reproduce with the latest version?

[cdce8p]

Please update pydantic to version 1.10.9 or newer. That does resolve the crash.
https://github.com/pydantic/pydantic/releases/tag/v1.10.9

[AlexWaygood]

Closing based on what @cdce8p says. If there's still a problem with the latest version of pydantic, best to open an issue over at the pydantic repo, since this is a problem with the pydantic mypy plugin rather than with core mypy :)

[cdce8p]

If there's still a problem with the latest version of pydantic, best to open an issue over at the pydantic repo, since this is a problem with the pydantic mypy plugin rather than with core mypy :)

Technically, one of my mypy PR broke it. 😅 But, at least for pydantic, I already contributed the fix.

[AlexWaygood]

Technically, one of my mypy PR broke it. 😅 But, at least for pydantic, I already contributed the fix.

Ah -- worth posting in #6617, perhaps? :)

[cdce8p]

Technically, one of my mypy PR broke it. 😅 But, at least for pydantic, I already contributed the fix.

Ah -- worth posting in #6617, perhaps? :)

I didn't change the API, only added a new required argument to TypeVarType / TypeVarExpr. Will do that though.

[AlexWaygood]

I didn't change the API, only added a new required argument to TypeVarType / TypeVarExpr. Will do that though.

Yup. Still might be nice to do so as a courtesy to plugin authors, though, if there's a chance it might break other plugins 👍

[cdce8p]

I didn't change the API, only added a new required argument to TypeVarType / TypeVarExpr. Will do that though.

Yup. Still might be nice to do so as a courtesy to plugin authors, though, if there's a chance it might break other plugins 👍

Done #6617 (comment)

[AlexWaygood]

Thank you <3