[6.2] Infer nonisolated conformances from witnesses #81344
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…d witnesses If all of the witnesses to a conformance are nonisolated, then infer that conformance as nonisolated rather than global-actor-isolated. This is only relevant when InferIsolatedConformances is enabled, and prevents that inference to help maintain source compatibility.
This request was looking through to the root conformance, which could mess with the caching bits. Sink the "is nonisolated conformance" bit down into ProtocolConformance, and have the request for a non-root conformance be defined in terms of the request for the root conformance.
This assertion will trigger whenever there is a cycle with a split-cached request. Remove the assertion.
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@swift-ci please test |
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I'm doing more investigation on this change still |
When defaulting to main-actor isolation, types that have synthesized conformances (e.g., for Equatable, Hashable, Codable) were getting nonisolated members by default. That would cause compiler errors because the conformances themselves defaulted to main-actor isolation when their types were. Be careful to only mark these members as 'nonisolated' when it makes sense, and leave them to get the isolation of their enclosing type when the conformance might have isolation. This ensures that one can use synthesis of these protocols along with default main-actor mode. There is a one-off trick here to force the synthesized CodingKeys to be nonisolated, because the CodingKey protocol requires Sendable. We'll separately consider whether to generalize this rule. More of rdar://150691429.
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@swift-ci please test |
hborla
approved these changes
May 9, 2025
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InferIsolatedConformancesis enabled, and prevents that inference to help maintain source compatibility. Related to this, don't force members introduced for compiler-synthesized conformances (Equatable,Hashable,Codable, etc.) to benonisolatedwhen inferring conditional conformances. This makes main-actor-by-default mode work with synthesized conformances so you can make a main-actor typeCodableand it'll correctly turn that into a main-actor-isolated conformance.InferIsolatedConformanceor when defaulting to the main actor.