[SE-0466] Don't infer @MainActor on types conforming to Sendable #81468
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DougGregor
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ktoso,
slavapestov,
hborla and
xedin
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@swift-ci please smoke test |
ktoso
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May 13, 2025
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Intentionally not merging because this need more discussion and experimentation |
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(I'm going to put this behind an experimental flag so we can play with it more) |
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Fixes rdar://154373088 / issue swiftlang#82523
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@swift-ci please smoke test |
When the default isolation is main-actor, don't infer @mainactor for a type that conforms to a protocol P in its primary definition when P inherits from Sendable. Such types should remain non-isolated because they're highly unlikely to be able to implement the P conformance (which cannot be isolated). Put this feature behind a new experimental flag, SendableProhibitsMainActorInference. Implements rdar://151029300
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@swift-ci please smoke test |
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@swift-ci please smoke test macOS |
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@swift-ci please smoke test Linux |
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Hello, This is a very welcome change 👍. It is good that libraries can influence the default MainActor isolation. I add this comment because |
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When the default isolation is main-actor, don't infer @mainactor for a type that conforms to a protocol P in its primary definition when P inherits from Sendable. Such types should remain non-isolated because they're highly unlikely to be able to implement the P conformance (which cannot be isolated).
Implements rdar://151029300