(🐞) the construction of a variable of `type`, applied with a type variable bound to a union, does not produce an type that is assignable to that type variable
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bug
- Dominant language
- Python
- Stars
- 20.6k
- Forks
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Description
from typing import TypeVar
T = TypeVar("T", bound=int | str)
def foo(t: T, tt: type[T]):
a: T = type(t)() # error
b: T = tt() # error
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reproducing the two assignment errors in the linked mypy-play playground, using the shown TypeVar bound and generic function. Trace how the type checker handles type(t)() and tt() when T is bound to a union. Done means the intended constructions are analyzed consistently and regression coverage verifies both assignments.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100