[Distributed] restore id synthesis in DerivedConformance infra for multi module cases

Author: ktoso

lib/Sema/DerivedConformanceDistributedActor.cpp

@@ -426,6 +426,32 @@ static FuncDecl *deriveDistributedActorSystem_invokeHandlerOnReturn(
 /******************************* PROPERTIES ***********************************/
 /******************************************************************************/
 
+// TODO(distributed): make use of this after all, but FORCE it?
+static ValueDecl *deriveDistributedActor_id(DerivedConformance &derived) {
+  assert(derived.Nominal->isDistributedActor());
+  auto &C = derived.Context;
+
+  // ```
+  // nonisolated let id: Self.ID // Self.ActorSystem.ActorID
+  // ```
+  auto propertyType = getDistributedActorIDType(derived.Nominal);
+
+  VarDecl *propDecl;
+  PatternBindingDecl *pbDecl;
+  std::tie(propDecl, pbDecl) = derived.declareDerivedProperty(
+      DerivedConformance::SynthesizedIntroducer::Let, C.Id_id, propertyType,
+      propertyType,
+      /*isStatic=*/false, /*isFinal=*/true);
+
+  // mark as nonisolated, allowing access to it from everywhere
+  propDecl->getAttrs().add(
+      new (C) NonisolatedAttr(/*IsImplicit=*/true));
+
+  derived.addMemberToConformanceContext(pbDecl, /*insertAtHead=*/true);
+  derived.addMemberToConformanceContext(propDecl, /*insertAtHead=*/true);
+  return propDecl;
+}
+
 static ValueDecl *deriveDistributedActor_actorSystem(
     DerivedConformance &derived) {
   auto &C = derived.Context;
@@ -454,9 +480,17 @@ static ValueDecl *deriveDistributedActor_actorSystem(
   // `actorSystem` MUST be the second field, because for a remote instance
   // we don't allocate memory after those two fields, so their order is very
   // important. The `hint` below makes sure the system is inserted right after.
-  auto id = derived.Nominal->getDistributedActorIDProperty();
-  derived.addMemberToConformanceContext(pbDecl, /*hint=*/id);
-  derived.addMemberToConformanceContext(propDecl, /*hint=*/id);
+  if (auto id = derived.Nominal->getDistributedActorIDProperty()) {
+    derived.addMemberToConformanceContext(pbDecl, /*hint=*/id);
+    derived.addMemberToConformanceContext(propDecl, /*hint=*/id);
+  } else {
+    // `id` will be synthesized next, and will insert at head,
+    // so in order for system to be SECOND (as it must be),
+    // we'll insert at head right now and as id gets synthesized we'll get
+    // the correct order: id, actorSystem.
+    derived.addMemberToConformanceContext(pbDecl, /*insertAtHead==*/true);
+    derived.addMemberToConformanceContext(propDecl, /*insertAtHead=*/true);
+  }
 
   return propDecl;
 }
@@ -551,14 +585,11 @@ deriveDistributedActorType_SerializationRequirement(
 
 ValueDecl *DerivedConformance::deriveDistributedActor(ValueDecl *requirement) {
   if (auto var = dyn_cast<VarDecl>(requirement)) {
+    if (var->getName() == Context.Id_id)
+      return deriveDistributedActor_id(*this);
+
     if (var->getName() == Context.Id_actorSystem)
       return deriveDistributedActor_actorSystem(*this);
-
-    if (var->getName() == Context.Id_id)
-      llvm_unreachable("DistributedActor.id MUST be synthesized earlier, "
-                       "because it is forced by the Identifiable conformance. "
-                       "If we attempted to do synthesis here, the earlier phase "
-                       "failed and something is wrong: please report a bug.");
   }
 
   if (auto func = dyn_cast<FuncDecl>(requirement)) {

lib/Sema/DerivedConformances.cpp

@@ -337,6 +337,10 @@ ValueDecl *DerivedConformance::getDerivableRequirement(NominalTypeDecl *nominal,
     if (name.isSimpleName(ctx.Id_unownedExecutor))
       return getRequirement(KnownProtocolKind::Actor);
 
+    // DistributedActor.id
+    if(name.isSimpleName(ctx.Id_id))
+      return getRequirement(KnownProtocolKind::DistributedActor);
+
     // DistributedActor.actorSystem
     if(name.isSimpleName(ctx.Id_actorSystem))
       return getRequirement(KnownProtocolKind::DistributedActor);

test/Distributed/Runtime/distributed_actor_in_other_module.swift

@@ -8,7 +8,6 @@
 // REQUIRES: concurrency
 // REQUIRES: distributed
 
-
 // UNSUPPORTED: use_os_stdlib
 // UNSUPPORTED: back_deployment_runtime