Unexpected Warning: Capture of non-sendable type

Using Swift
,
2

There is an article about this on swift.org: Sendable Metatypes.

You need to add a SendableMetatype constraint. You can add it for all P like this:

protocol P: Sendable {
    associatedtype State: P2 & SendableMetatype
}

Or you can add it for all Foo like this:

final class Foo<T: P> where T.State: SendableMetatype {

Or you can add it for just that init like this:

    init(initialState: T.State) where T.State: SendableMetatype {

I think the use of SendableMetatype should back-deploy (it is a marker protocol with no constraints and the documentation says it is available since iOS 8, macOS 10.10, etc.). However, Xcodes older than 26 beta 1 don't know it. So you may also want to add this definition:

#if compiler(<6.2)
public typealias SendableMetatype = Any
#endif

You can find more discussion here: Issues with SE-0470: Global-actor isolated conformances

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