[IRGen] Fix witness table miscompilation. #60529
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al45tair
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@swift-ci Please smoke test |
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Hmmm. That exploded unexpectedly. I'll keep digging then. |
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Is it possible to add a test case? |
al45tair
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Should be, yes. |
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Having looked at this a bit further, I don't think it's feasible to write a test case that will work on macOS (this only affects synthesized conformances, which means the protocol in question needs to be in the Swift standard library, but on macOS that's dynamically linked and always resilient; building a test case there would require a fairly heroic effort), but it's probably possible on Linux. Trying to get a Linux build up so I can test it. |
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It turns out that it was feasible. Just somewhat tricky to get right (the compiler doesn't give very helpful error messages when bits of the |
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Failed on Windows and Linux, probably because of the section name. Looking at that now. |
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If a foreign type conforms to a protocol, and that conformance is not resilient, we were emitting an instantantiation function but it would never be called because we weren't emitting the `GenericWitnessTable` that would have contained a reference to it. This was happening because of a missing `isSynthesizedNonUnique()` call in `isDependentConformance()`. rdar://97290618
isDependentConformance() should always check for synthesized conformances, so do that further up the function. Also add a test. rdar://97290618
Changed the test case to pattern match various parts to make it work on 32-bit. rdar://97290618
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Windows adds a `comdat` flag. rdar://97290618
Linux uses different section names. rdar://97690618
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@swift-ci Please smoke test |
If a foreign type conforms to a protocol, and that conformance is not resilient, we were emitting an instantantiation function but it would never be called because we weren't emitting the
GenericWitnessTablethat would have contained a reference to it.This was happening because of a missing
isSynthesizedNonUnique()call inisDependentConformance().rdar://97290618