Sema: Relax primary associated type matching in matchExistentialTypes() #78559
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Recently I found a soundness hole here, where we would allow conversion between `any P<T>` and `any Q<T>` even if P and Q have different primary associated types. However, the fix was too strict, because we still want to allow the conversion when the associated types have the same name. Fixes rdar://141968103.
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@swift-ci Please test source compatibility |
xedin
approved these changes
Jan 10, 2025
AnthonyLatsis
approved these changes
Jan 10, 2025
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I found a soundness hole and fixed it in #77178, where we would allow conversion between
any P<T>andany Q<T>wherePinherits fromQ, even if P and Q declare different primary associated types.However, the fix was too strict, because we still want to allow the conversion when the associated types have the same name -- if one protocol inherits from two protocols that both declare an
A, the twoAs become semantically equivalent.Fixes rdar://141968103.