bad-argument-type - false negative when calling decorator function with wrong type #5536

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1. DetachHead

   changed the title [-]no error when calling decorator function with wrong type[/-] [+]`bad-argument-type` - false negative when calling decorator function with wrong type[/+] on Nov 5, 2026
2. DetachHead commented on Nov 5, 2026

   

   DetachHead

   on Nov 5, 2026

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   it works when calling the function normally:

   def deco(cls: int) -> int: ...
   
   
   class Baz: ...
   
   deco(Baz) # error: Argument `type[Baz]` is not assignable to parameter `cls` with type `int` in function `deco` [bad-argument-type]

   pyright and mypy have had similar issues in the past, caused by the fact that they also use different logic for checking decorator calls for some reason. ideally it should use the same logic used for checking a regular function call to avoid issues like this.
3. rchen152

   added

   typechecking

   on Nov 5, 2026
4. rchen152

   added the

   Bug

   issue type on Nov 5, 2026
5. rchen152 commented on Nov 5, 2026

   

   rchen152

   on Nov 5, 2026

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   Likely related: #1180
6. connernilsen

   self-assigned this

   on Nov 5, 2026
7. connernilsen commented on Nov 5, 2026

   

   connernilsen

   on Nov 5, 2026

   Last edited by connernilsen

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   Yeah, I think #2294 (PR for #1180) may fix this, but will keep an eye on it to make sure once it's landed