[Concurrency] Only deprecate AnyActor, and update more tests.

Obsoleting `AnyActor` in Swift 6 blocks the Concurrency library itself
from migrating to Swift 6, because `Actor` and `DistributedActor` have to
preserve their refinement of `AnyActor` to avoid breaking code currently
using the marker protocol. There's no way to move protocol refinement into
an extension so that the use-site declaration can be obsoleted, so we're
stuck with just the deprecation of `AnyActor`.

Author: hborla

stdlib/public/Concurrency/Actor.swift

@@ -29,7 +29,6 @@ import Swift
 @_marker
 @available(SwiftStdlib 5.1, *)
 @available(*, deprecated, message: "Use 'any Actor' with 'DistributedActor.asLocalActor' instead")
-@available(swift, obsoleted: 6.0, message: "Use 'any Actor' with 'DistributedActor.asLocalActor' instead")
 public protocol AnyActor: AnyObject, Sendable {}
 
 /// Common protocol to which all actors conform.

test/Distributed/actor_protocols.swift

@@ -93,17 +93,17 @@ struct S2: DistributedActor {
 
 // ==== -----------------------------------------------------------------------
 
-actor A3: AnyActor {} // ok
-distributed actor DA3: AnyActor {} // ok
+actor A3: AnyActor {} // expected-warning {{'AnyActor' is deprecated: Use 'any Actor' with 'DistributedActor.asLocalActor' instead}}
+distributed actor DA3: AnyActor {} // expected-warning {{'AnyActor' is deprecated: Use 'any Actor' with 'DistributedActor.asLocalActor' instead}}
 
-class C3: AnyActor, @unchecked Sendable {
+class C3: AnyActor, @unchecked Sendable { // expected-warning {{'AnyActor' is deprecated: Use 'any Actor' with 'DistributedActor.asLocalActor' instead}}
   // expected-error@-1{{non-actor type 'C3' cannot conform to the 'AnyActor' protocol}} {{1-6=actor}}
 }
 
-struct S3: AnyActor {
+struct S3: AnyActor { // expected-warning {{'AnyActor' is deprecated: Use 'any Actor' with 'DistributedActor.asLocalActor' instead}}
   // expected-error@-1{{non-class type 'S3' cannot conform to class protocol 'AnyActor'}}
 }
 
-enum E3: AnyActor {
+enum E3: AnyActor { // expected-warning {{'AnyActor' is deprecated: Use 'any Actor' with 'DistributedActor.asLocalActor' instead}}
   // expected-error@-1{{non-class type 'E3' cannot conform to class protocol 'AnyActor'}}
 }

test/decl/protocol/special/DistributedActor.swift

@@ -68,7 +68,7 @@ distributed actor D5: P1 {
 
 // Make sure the conformances have been added implicitly.
 func acceptDistributedActor<Act: DistributedActor>(_: Act.Type) { }
-func acceptAnyActor<Act: AnyActor>(_: Act.Type) { }
+func acceptAnyActor<Act: AnyActor>(_: Act.Type) { } // expected-warning {{'AnyActor' is deprecated: Use 'any Actor' with 'DistributedActor.asLocalActor' instead}}
 
 func testConformance() {
   acceptDistributedActor(D1.self)
@@ -86,4 +86,4 @@ distributed actor A: P {
   distributed func foo() { }
   // expected-error@-1{{actor-isolated distributed instance method 'foo()' cannot be used to satisfy nonisolated protocol requirement}}
 }
-// ---
+// ---