ClangImporter: Support for subclass existentials #8847
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Class-constrained existentials usually have unknown reference counting in Swift, because they can contain either Objective-C or native Swift classes. But if the class existential has a superclass bound which is known to be an imported Objective-C class, we can use Objective-C reference counting instead of unknown reference counting. This is tested with the next commit that adds ClangImporter support.
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@swift-ci Please test |
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In Swift 3, an Objective-C type like SomeClass <SomeProtocol> is imported as SomeClass. The protocol qualification is erased unless the class bound is 'id' or 'Class'. Importing such types as class-constrained existentials is a source breaking change, so the new behavior is only enabled in Swift 4 mode. Furthermore as a transitional step the staging flag -enable-experimental-subclass-existentials has to be passed in also. The flag will soon be removed.
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@swift-ci Please clean test |
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@swift-ci smoke test Linux |
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@aciidb0mb3r Can you take a look at the Linux test failure here? https://ci.swift.org/job/swift-PR-Linux/6876/consoleFull#-5114079ee1a197b-acac-4b17-83cf-a53b95139a76 |
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Ah, that was a non-deterministic test. It was fixed by: swiftlang/swift-package-manager#1097 |
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Thanks! |
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