[Distributed] Add ModuleInterface test with generic distributed actor

lib/AST/DistributedDecl.cpp

@@ -309,7 +309,16 @@ Type swift::getAssociatedTypeOfDistributedSystemOfActor(
   auto subs = SubstitutionMap::getProtocolSubstitutions(
       actorProtocol, actorType->getDeclaredInterfaceType(), actorConformance);
 
-  return memberTy.subst(subs)->getReducedType(sig);
+  memberTy = memberTy.subst(subs);
+
+  // If substitution is still not fully resolved, let's see if we can
+  // find a concrete replacement in the generic signature.
+  if (memberTy->hasTypeParameter() && sig) {
+    if (auto concreteTy = sig->getConcreteType(memberTy))
+      return concreteTy;
+  }
+
+  return memberTy;
 }
 
 /******************************************************************************/

test/ModuleInterface/distributed-actor.swift

@@ -1,23 +1,43 @@
 // RUN: %empty-directory(%t)
-// RUN: %target-swift-emit-module-interface(%t/Library.swiftinterface) %s -module-name Library
-// RUN: %target-swift-typecheck-module-from-interface(%t/Library.swiftinterface) -module-name Library
+// RUN: split-file %s %t
+
+// RUN: %target-swift-frontend -emit-module -module-name Library \
+// RUN:     -swift-version 5 -enable-library-evolution \
+// RUN:     -o %t/Library.swiftmodule \
+// RUN:     -emit-module-interface-path %t/Library.swiftinterface \
+// RUN:     %t/Library.swift
+
+/// Verify the interface
 // RUN: %FileCheck %s < %t/Library.swiftinterface
 
+/// Verify that we can build from the Library.swiftmodule
+// RUN: %target-swift-frontend -typecheck -module-name Client \
+// RUN:     -swift-version 5 \
+// RUN:     %t/Client.swift -I%t
+
+/// Verify what we can build from a swiftinterface, when swiftmodule was deleted
+// RUN: rm %t/Library.swiftmodule
+// RUN: %target-swift-frontend -typecheck -module-name Client \
+// RUN:     -swift-version 5 \
+// RUN:     %t/Client.swift -I%t
+
 // REQUIRES: distributed
 
+//--- Library.swift
+
 import Distributed
 
 // CHECK-NOT:  #if compiler(>=5.3) && $Actors
 // CHECK:      @available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0, *)
 // CHECK-NEXT: distributed public actor DA {
 @available(SwiftStdlib 5.7, *)
 public distributed actor DA {
-  // CHECK: @_compilerInitialized nonisolated final public let id: Distributed.LocalTestingActorID
+  // CHECK: @_compilerInitialized nonisolated final public let id: Distributed.LocalTestingDistributedActorSystem.ActorID
   // CHECK: nonisolated final public let actorSystem: Library.DA.ActorSystem
   // CHECK: public typealias ActorSystem = Distributed.LocalTestingDistributedActorSystem
   public typealias ActorSystem = LocalTestingDistributedActorSystem
 
-  // CHECK:       public static func resolve(id: Distributed.LocalTestingActorID, using system: Library.DA.ActorSystem) throws -> Library.DA
+  // CHECK:       public static func resolve(id: Distributed.LocalTestingDistributedActorSystem.ActorID, using system: Library.DA.ActorSystem) throws -> Library.DA
   // CHECK:       public typealias ID = Distributed.LocalTestingDistributedActorSystem.ActorID
   // CHECK:       public typealias SerializationRequirement = any Swift.Decodable & Swift.Encodable
   // CHECK:       {{@objc deinit|deinit}}
@@ -31,6 +51,27 @@ public distributed actor DA {
   // CHECK-NEXT:  }
 }
 
+// CHECK-NOT: #if compiler(>=5.3) && $Actors
+// CHECK: @available(macOS 9999, iOS 9999, watchOS 9999, tvOS 9999, *)
+// CHECK-NEXT: distributed public actor DAG<ActorSystem> where ActorSystem : Distributed.DistributedActorSystem, ActorSystem.SerializationRequirement == any Swift.Decodable & Swift.Encodable {
+@available(SwiftStdlib 6.0, *)
+public distributed actor DAG<ActorSystem> where ActorSystem: DistributedActorSystem<any Codable> {
+  // CHECK: @_compilerInitialized nonisolated final public let id: ActorSystem.ActorID
+  // CHECK: nonisolated final public let actorSystem: ActorSystem
+
+// CHECK: public static func resolve(id: ActorSystem.ActorID, using system: ActorSystem) throws -> Library.DAG<ActorSystem>
+// CHECK: public typealias ID = ActorSystem.ActorID
+// CHECK: public typealias SerializationRequirement = any Swift.Decodable & Swift.Encodable
+// CHECK: {{@objc deinit|deinit}}
+// CHECK: nonisolated public var hashValue: Swift.Int {
+// CHECK:   get
+// CHECK: }
+// CHECK: public init(actorSystem system: ActorSystem)
+// CHECK: @available(iOS 9999, tvOS 9999, watchOS 9999, macOS 9999, *)
+// CHECK: @_semantics("defaultActor") nonisolated final public var unownedExecutor: _Concurrency.UnownedSerialExecutor {
+// CHECK:   get
+// CHECK: }
+}
 
 // CHECK-NOT: #if compiler(>=5.3) && $Actors
 // CHECK:     @available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0, *)
@@ -41,3 +82,21 @@ public distributed actor DA {
 // CHECK-NOT: #if compiler(>=5.3) && $Actors
 // CHECK:     @available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0, *)
 // CHECK-NEXT:extension Library.DA : Swift.Decodable {}
+
+// CHECK-NOT: #if compiler(>=5.3) && $Actors
+// CHECK: @available(macOS 9999, iOS 9999, watchOS 9999, tvOS 9999, *)
+// CHECK-NEXT: extension Library.DAG : Distributed.DistributedActor {}
+
+//--- Client.swift
+
+import Distributed
+import Library
+
+@available(SwiftStdlib 6.0, *)
+func main() {
+  let da: DA? = nil
+  _ = da
+
+  let dag: DAG<LocalTestingDistributedActorSystem>? = nil
+  _ = dag
+}