Skip to content

Typing of return type of a generic function #8946

@PeterLaudel

Description

@PeterLaudel

Note: if you are reporting a wrong signature of a function or a class in
the standard library, then the typeshed tracker is better suited
for this report: https://github.com/python/typeshed/issues

Please provide more information to help us understand the issue:

  • Are you reporting a bug, or opening a feature request?
    Reporting Bug
  • Please insert below the code you are checking with mypy,
    or a mock-up repro if the source is private. We would appreciate
    if you try to simplify your case to a minimal repro.
from typing import TypeVar, Type, Optional, List, cast

T = TypeVar("T")


def some_func(something: Type[T]) -> T:
    return "something"


some_func(Optional[str])
some_func(Type[str])
  • What is the actual behavior/output?
typing_test.py:7: error: Incompatible return value type (got "str", expected "T")
typing_test.py:10: error: Argument 1 to "some_func" has incompatible type "object"; expected "Type[<nothing>]"
typing_test.py:11: error: Argument 1 to "some_func" has incompatible type "object"; expected "Type[<nothing>]"
  • What is the behavior/output you expect?
    Actually since this answer https://stackoverflow.com/a/42226930 I would expect it work. It also worked in previsous versions.
  • What are the versions of mypy and Python you are using?
    mypy 0.780
    python 3.7.7

(You can freely edit this text, please remove all the lines
you believe are unnecessary.)

Metadata

Metadata

Assignees

No one assigned

    Labels

    No labels
    No labels

    Projects

    No projects

    Milestone

    No milestone

    Relationships

    None yet

    Development

    No branches or pull requests

    Issue actions