Add support for `@isolated(any)` to `withoutActuallyEscaping`

[ph1ps]

Motivation

According to the diagnostic: withoutActuallyEscaping is currently unimplemented for @isolated(any) function values @isolated(any) was deliberately turned off for withoutActuallyEscaping. However, to fully migrate a function like this:

func send(
  operation: @Sendable () async -> Void
) async {
  await withoutActuallyEscaping(operation) { operation in
    await withTaskGroup(of: Void.self) { taskGroup in
      taskGroup.addTask {
        await operation()
      }
    }
  }
}

... to mimic the signature of TaskGroup.addTask and to support all Swift 6 features of task creation APIs, we'd need support for this. If you want to, I can also provide a more realistic sample code where this would help.

Workaround is of course to use @escapable closures, and not using withoutActuallyEscaping. So this would be more of an ergonomic improvement.

Proposed solution

As already stated in the motivation, I'd propose to add support of @isolated(any) for withoutActuallyEscaping to get better ergonomics.

Alternatives considered

No response

Additional information

Forum thread: https://forums.swift.org/t/withoutactuallyescaping-and-isolated-any/74748