A `@preconcurrency` conformance to an inherited protocol should imply
`@preconcurrency` on its parents as well. For example:
```swift
protocol Parent {
func a()
}
protocol Child: Parent {
func b()
}
@MainActor
class Test: @preconcurrency Child {
func a() {
}
func b() {
}
}
```
`Test` conformance to `Parent` implied by its conformance to `Child`
should carry `@preconcurrency` and inject dynamic actor isolation checks
to witness of `a()`.
Resolves: https://github.com/apple/swift/issues/74294
Resolves: rdar://129599097
When a witness is part of a `@preconcurrency` conformance, suppress
Sendable checking for that witness because we assume that the caller is
correctly invoking this witness from within the right isolation
domain. This property is dynamically checked.
Fixes https://github.com/apple/swift/issues/74057.
When diagnosing a case where an actor-isolated witness cannot satisfy
a non-isolated requirement, also suggest that the conformance could be
annotated with `@preconcurrency`.
Suppress warnings/errors when actor isolated synchroneous witness
is matched against `@preconcurrency` conformance requirement.
Witness thunk assumes isolation of the witness but instead of a
hop to its executor it would emit a runtime check to make sure
that its always called from the expected context.
