[TypeJoin] Implement Type::join for protocols and protocol compositions. #19677
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This is mostly complete, but we still need to add support for joins between these two types and other types.
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@swift-ci Please test source compatibility |
lib/AST/TypeJoinMeet.cpp
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| assert(First != second); | ||
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| // FIXME: Handle other types here. | ||
| if (First->getKind() != TypeKind::Protocol && |
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You should be using isa<> instead of getKind(), I think
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Ah yes, I'll fix that up.
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Is that because isa<> strips sugar? I still can’t say when it would make sense to use getKind vs. isa<> with confidence... is getKind supposed to be used only by switch statements?
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In general that's a good reason to use is<> and getAs<>, but in this case we're working with CanTypes so that shouldn't make a difference (*). It's generally shorter and more idiomatic to use these templated functions.
Add a comment explaining that the distributive law isn't generally true for lattices but should be for ours, and fix up the test case to not use the real stdlib Strideable protocol in a couple places.
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@swift-ci Please smoke test |
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@swift-ci Please test source compatibility |
lib/AST/TypeJoinMeet.cpp
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| assert(First != second); | ||
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| // FIXME: Handle other types here. | ||
| if (!First->is<ProtocolType>() && |
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This is First->isExistentialType()
lib/AST/TypeJoinMeet.cpp
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| } | ||
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| // Return true if the first ProtocolDecl is a supertype of the second. | ||
| static bool isSupertypeOf(ProtocolDecl *super, ProtocolDecl *sub) { |
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Is this not the same as ProtocolDecl::inheritsFrom()?
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Close enough for my purposes, but the function I defined returns true if they are the same type. It shouldn't be calling them with the same type though, so I'll change it.
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@swift-ci Please smoke test |
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@swift-ci Please test source compatibility |
This is mostly complete, but we still need to add support for joins
between these two types and other types.