Support assertion style type guards in exhaustive branch analysis #11238

Activity

1. KotlinIsland

   added

   feature

   on Oct 1, 2021
2. hi-ogawa commented on Oct 17, 2021

   

   hi-ogawa

   on Oct 17, 2021

   Contributor

   More actions

   Considering the behavior of the example below, "narrowing" is happening in some sense, but possibly mypy's join type is producing join(int, str) = object.

   # test1.py
   
   class P:
       pass
   
   
   class C1(P):
       pass
   
   
   class C2(P):
       pass
   
   
   def f(a: object, b: bool) -> None:
       if b:
           assert isinstance(a, C1)
       else:
           assert isinstance(a, C2)
   
       reveal_type(a)  # note: Revealed type is "test1.P"
3. JelleZijlstra

   added

   topic-join-v-unionUsing join vs. using unionsUsing join vs. using unions

   on Mar 19, 2022
4. AlexWaygood

   added

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

   on Mar 28, 2022
5. brianschubert commented on Apr 18, 2025

   

   brianschubert

   on Apr 18, 2025

   Collaborator

   More actions

   This was implemented in #18538, which should release with v1.16.0
6. brianschubert

   closed this as completedon Apr 18, 2025