Incorrect union narrowing in chained conditionals #12208

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1. JaviFuentes94

   added

   bugmypy got something wrongmypy got something wrong

   on Feb 18, 2022
2. erictraut commented on Feb 19, 2022

   

   erictraut

   on Feb 19, 2022

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   Which version of mypy are you using? I'm not able to repro this error with the latest published version.
3. JelleZijlstra commented on Mar 19, 2022

   

   JelleZijlstra

   on Mar 19, 2022

   Member

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   Doesn't repro for me either: https://mypy-play.net/?mypy=latest&python=3.10&gist=e2c735beb847d6da4d53477050f3a119
4. JelleZijlstra

   closed this as completedon Mar 19, 2022
5. JelleZijlstra

   added

   topic-type-narrowingConditional type narrowing / binderConditional type narrowing / binder

   on Mar 19, 2022
6. JaviFuentes94 commented on Mar 22, 2022

   

   JaviFuentes94

   on Mar 22, 2022

   Last edited by JaviFuentes94

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   Hello again, sorry I made a mistake while testing my minimal example. The problem comes with a Literal that is an enum field:

   from typing_extensions import Literal
   from typing import Union, Dict
   import enum
   
   class Types(str, enum.Enum):
       animal = "animal"
       plant = "plant"
   
   
   class Animal:
       name: Literal[Types.animal]
       n_legs: int
   
   class Plant:
       name: Literal[Types.plant]
   
   def get_n_legs(item: Union[Animal, Plant]):
       if item.name == Types.animal and item.n_legs > 6:   
           return "Many" 
   

   Here you can reproduce it: https://mypy-play.net/?mypy=latest&python=3.10&gist=dfcdd1d12e53c80d0e58ba5ed8750ccf
7. JelleZijlstra

   reopened this on Mar 22, 2022
8. mikaelarguedas commented on Mar 4, 2023

   

   mikaelarguedas

   on Mar 4, 2023

   Last edited by mikaelarguedas

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   Hey there,

   I believe I ran into another occurrence of this. It looks like the type has not been narrowed by the first if statement.
   Happens with latest mypy on Python3.8.
   Trying it on https://mypy-play.net looks to happen on more recent versions of Python as well.

   Reproducible example: https://mypy-play.net/?mypy=latest&python=3.11&flags=verbose&gist=07d004a22a748059c834ff42d690c2ed

   from typing import Optional, Union
   
   
   class RangeVals:
       """Hold a parameter value range."""
   
       def __init__(
           self,
           min_val: Union[int, float],
           max_val: Union[int, float],
       ) -> None:
           self.min_val = min_val
           self.max_val = max_val
   
   
   def functionn(default_val: Union[str, float, int], rangeval: RangeVals):
       if type(default_val) != type(rangeval.min_val):
           raise TypeError("foo")
       if default_val < rangeval.min_val:
           raise ValueError("bar")
   
   
   functionn("abc", RangeVals(min_val=3, max_val=10))
9. erictraut commented on Aug 13, 2023

   

   erictraut

   on Aug 13, 2023

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   The original bug in this issue appears to have been fixed in mypy 1.4.

   @mikaelarguedas, your issue is unrelated to OP's bug. The behavior in your sample is expected behavior in mypy.
10. hauntsaninja commented on Aug 13, 2023

    

    hauntsaninja

    on Aug 13, 2023

    Collaborator

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    I fixed this in #11521
11. hauntsaninja

    closed this as completedon Aug 13, 2023