Fix crash on ErasedType and covers_at_runtime
#11924
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JukkaL
reviewed
Jan 6, 2022
mypy/subtypes.py
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| @@ -1167,6 +1167,14 @@ def restrict_subtype_away(t: Type, s: Type, *, ignore_promotions: bool = False) | |||
| def covers_at_runtime(item: Type, supertype: Type, ignore_promotions: bool) -> bool: | |||
| """Will isinstance(item, supertype) always return True at runtime?""" | |||
| item = get_proper_type(item) | |||
| supertype = get_proper_type(supertype) | |||
| if (isinstance(item, (ErasedType, DeletedType)) | |||
| or isinstance(supertype, (ErasedType, DeletedType))): | |||
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Hmm I wonder if ErasedType instances can be nested inside unions, for example, and still cause a crash. Maybe erase_type should just propagate erased types unmodified? I don't think that DeletedType can be nested so it seems safe to handle here, though I'm not sure we need special casing for it. Did you find a use case where we encounter deleted types here, or is it here more as a defensive measure?
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Hm, good idea. I will try it!
Did you find a use case where we encounter deleted types here, or is it here more as a defensive measure?
More like a defensive programming. I will remove it, because it does not make much sense without ErasedType.
hauntsaninja
reviewed
Jan 6, 2022
Co-authored-by: Shantanu <12621235+hauntsaninja@users.noreply.github.com>
tushar-deepsource
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to DeepSourceCorp/mypy
that referenced
this pull request
Jan 20, 2022
Closes python#11913 Refs python#11273 Co-authored-by: Shantanu <12621235+hauntsaninja@users.noreply.github.com>
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Closes #11913
Refs #11273
CC @hauntsaninja