Bug Report
Any attempt to call isinstance with a variable annotated as a TypeAlias seems to result in the error message error: Parameterized generics cannot be used with class or instance checks, even if the aliased type is non-generic. mypy_primer points at #18173 as the breaking commit, but that PR seems to have been intended to deal with type aliases of generic types; it seems that we're treating all TypeAlias-based aliases as generic types, which AFAICT is broader than intended.
To Reproduce
MyPy playground link, using current master
from typing import Any, TypeAlias
class Foo:
pass
Alias: TypeAlias = Foo
def is_foo(x: Any) -> bool:
return isinstance(x, Alias)Expected Behavior
MyPy finds no errors, matching the runtime behavior. Pyright and mypy 1.4 both find no errors in my minimal example.
Actual Behavior
Per the playground link:
main.py:9: error: Parameterized generics cannot be used with class or instance checks [misc]
Found 1 error in 1 file (checked 1 source file)
Your Environment
I found this when dogfooding mypy master commit c4e2eb7 against Dropbox's internal Python repo, but mypy_primer also reproduces the same thing, as does mypy playground.
Bug Report
Any attempt to call
isinstancewith a variable annotated as aTypeAliasseems to result in the error messageerror: Parameterized generics cannot be used with class or instance checks, even if the aliased type is non-generic. mypy_primer points at #18173 as the breaking commit, but that PR seems to have been intended to deal with type aliases of generic types; it seems that we're treating allTypeAlias-based aliases as generic types, which AFAICT is broader than intended.To Reproduce
MyPy playground link, using current master
Expected Behavior
MyPy finds no errors, matching the runtime behavior. Pyright and mypy 1.4 both find no errors in my minimal example.
Actual Behavior
Per the playground link:
Your Environment
I found this when dogfooding mypy master commit c4e2eb7 against Dropbox's internal Python repo, but mypy_primer also reproduces the same thing, as does mypy playground.