error: Expression is of type "Any", not "Any" (Using `Any` as a `type`)
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bug
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- Python
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Description
Here is a minimum reproducible example of this bug:
from typing import Any, assert_type
def foo[T](typ: type[T]) -> T: ...
assert_type(foo(Any), Any)
reveal_type(foo(Any), Any)
reveal_type(Any)
which produces this output:
error: Expression is of type "Any", not "Any" [assert-type]
note: Revealed type is "typing.Any"
note: Revealed type is "def () -> typing.Any"
I did not expect this to cause any mypy errors.
Or, it would say that Any is not a type.
Your Environment
- Mypy version used: mypy 1.19.1 (compiled: yes)
- Mypy command-line flags: NA
- Mypy configuration options from
mypy.ini(and other config files): NA - Python version used: 3.13.9 (also reproduced in 3.14.3)
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
No repository file or test is named. Start by running the provided reproducer against mypy 1.19.1, then trace how Any is handled when passed to type[T] and by assert_type; done means the example produces no erroneous assert-type error while retaining the revealed types.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- devtools
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100