python / python/mypy

Stubgen: Instance Attributes set to `Incomplete` even though explicit declared

Open
#14,673 5 comments 2 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

feature topic-stubgen
Dominant language
Python
Stars
20.6k
Forks
3.3k
PR merge metrics
PR metrics pending

Description

Bug Report

I am using Stubgen to type my files.
Here, I have a class with a lot of instance attributes.
They are all declared within the __init__ method.
They are set using a method which returns Any as type, but manually set to the correct type:

When generating the stub file, all are set to Incomplete instead of the highlighted code.
Trying to use # type: str behind it results in a error: Critical error during semantic analysis: foo/bar.py:424242: error: invalid syntax [syntax]

To Reproduce

from typing import Any


class MyClass:

    def __init__(self) -> None:
        bar = Bar("test")
        self.test: str = bar.foo("test")


class Bar:
    def __init__(self, anything: str) -> None:
          pass

    def foo(self, test: str) -> Any:
         return test

results in:

from _typeshed import Incomplete
from typing import Any

class MyClass:
    test: Incomplete
    def __init__(self) -> None: ...

class Bar:
    def __init__(self, anything: str) -> None: ...
    def foo(self, test: str) -> Any: ...

Gist URL: https://gist.github.com/27dfb95516013fa15ed80c1411ce5a4e
Playground URL: https://mypy-play.net/?mypy=latest&python=3.9&gist=27dfb95516013fa15ed80c1411ce5a4e

Expected Behavior

I want the attribute to have the correct, annotated type.

from typing import Any

class MyClass:
    test: str
    def __init__(self) -> None: ...

class Bar:
    def __init__(self, anything: str) -> None: ...
    def foo(self, test: str) -> Any: ...

Actual Behavior

It is exported as incomplete

from _typeshed import Incomplete
from typing import Any

class MyClass:
    test: Incomplete
    def __init__(self) -> None: ...

class Bar:
    def __init__(self, anything: str) -> None: ...
    def foo(self, test: str) -> Any: ...

Your Environment

  • Mypy version used: mypy 1.0.0 (compiled: yes)
  • Mypy command-line flags: stubgen ./foo_bar -o .
  • Mypy configuration options from mypy.ini (and other config files): None used
  • Python version used: Python 3.10.9

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reproducing the report with the shown Python example and stubgen ./foo_bar -o ., then inspect stubgen's handling of explicitly annotated instance attributes assigned from a method returning Any. Done means the generated stub contains test: str rather than importing and using Incomplete, without producing the reported syntax error.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
tooling
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
45/100

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.