[Runtime] Fixed shared cache protocol conformance lookup with subclasses. #36468
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…ses.
Match the logic used in the non-shared-cache case, where we walk up the class hierarchy to find the class where the conformance actually applies. This is important in cases like:
class Super<T> : Proto {}
class Sub: Super<Int> {}
Looking up the conformance `Sub: Proto` without this logic causes it to attempt to find the witness table for `Sub<Int>`, which fails. The correct logic looks up the witness table for `Super<Int>`.
While we're in there, fix a bug in the shared cache validation code (std::find wasn't checked for failure correctly) and add a `SWIFT_DEBUG_ENABLE_SHARED_CACHE_PROTOCOL_CONFORMANCES` environment variable to allow us to turn the shared cache integration off at runtime.
rdar://75431771
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@swift-ci please test |
cooperp
approved these changes
Mar 17, 2021
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Match the logic used in the non-shared-cache case, where we walk up the class hierarchy to find the class where the conformance actually applies. This is important in cases like:
class Super : Proto {}
class Sub: Super {}
Looking up the conformance
Sub: Protowithout this logic causes it to attempt to find the witness table forSub<Int>, which fails. The correct logic looks up the witness table forSuper<Int>.While we're in there, fix a bug in the shared cache validation code (std::find wasn't checked for failure correctly) and add a
SWIFT_DEBUG_ENABLE_SHARED_CACHE_PROTOCOL_CONFORMANCESenvironment variable to allow us to turn the shared cache integration off at runtime.rdar://75431771