Isolated conformances #2720
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Isolated conformances #2720
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Also pull in Slava's lovely idea of the SendableMetatype protocol, and narrow the "strict sendable metatypes" check to type parameters that have non-marker protocol requirements.
rjmccall
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Instead of using `isolated P` for an isolated conformance, we could use the global actor spelling. Document it.
This was rewritten and moved in an earlier iteration.
I've gotten a bunch of feedback that `isolated P` is confusing, and `@MainActor P` is both clearer and more extensible. Rework the proposal to use this new syntax, and bring in a few future directions that are enabled by it.
This was in future work, but make this an official part of the proposal now that SE-0466 is in review.
hborla
reviewed
Mar 14, 2025
| The proposed solution describes the basic shape of isolated conformances and how they interact with the type system. This section goes into more detail on the data-race safety issues that arise from the introduction of isolated conformances into the language. Then it details three rules that, together, ensure freedom from data race safety issues in the presence of isolated conformances: | ||
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| 1. An isolated conformance can only be used within its isolation domain. | ||
| 2. When an isolated conformance is used to satisfy a generic constraint `T: P`, the generic signature must not include either of the following constraints: `T: Sendable` or `T.Type: Sendable`. |
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I think this is leftover from an earlier iteration that used T.Type: Sendable rather than T: SendableMetatype
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| 2. When an isolated conformance is used to satisfy a generic constraint `T: P`, the generic signature must not include either of the following constraints: `T: Sendable` or `T.Type: Sendable`. | |
| 2. When an isolated conformance is used to satisfy a generic constraint `T: P`, the generic signature must not include either of the following constraints: `T: Sendable` or `T: SendableMetatype`. |
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