Allow accessing let properties in deinit isolated on different actor

Author: nickolas-pohilets

lib/Sema/TypeCheckConcurrency.cpp

@@ -509,9 +509,9 @@ Type swift::getExplicitGlobalActor(ClosureExpr *closure) {
 
 /// A 'let' declaration is safe across actors if it is either
 /// nonisolated or it is accessed from within the same module.
-static bool varIsSafeAcrossActors(const ModuleDecl *fromModule,
-                                  VarDecl *var,
+static bool varIsSafeAcrossActors(const ModuleDecl *fromModule, VarDecl *var,
                                   const ActorIsolation &varIsolation,
+                                  std::optional<ReferencedActor> actorInstance,
                                   ActorReferenceResult::Options &options) {
 
   bool accessWithinModule =
@@ -559,6 +559,11 @@ static bool varIsSafeAcrossActors(const ModuleDecl *fromModule,
       return false;
     }
 
+    // If it's distributed, but known to be local, it's ok
+    // TODO: Check if this can be obtained from the isolation, without a need for separate argument
+    if (actorInstance && actorInstance->isKnownToBeLocal()) {
+      return true;
+    }
     // If it's distributed, generally variable access is not okay...
     if (auto nominalParent = var->getDeclContext()->getSelfNominalTypeDecl()) {
       if (nominalParent->isDistributedActor())
@@ -585,7 +590,7 @@ bool swift::isLetAccessibleAnywhere(const ModuleDecl *fromModule,
                                     VarDecl *let,
                                     ActorReferenceResult::Options &options) {
   auto isolation = getActorIsolation(let);
-  return varIsSafeAcrossActors(fromModule, let, isolation, options);
+  return varIsSafeAcrossActors(fromModule, let, isolation, std::nullopt, options);
 }
 
 bool swift::isLetAccessibleAnywhere(const ModuleDecl *fromModule,
@@ -6762,7 +6767,7 @@ static ActorIsolation getActorIsolationForReference(ValueDecl *decl,
   if (auto var = dyn_cast<VarDecl>(decl)) {
     auto *fromModule = fromDC->getParentModule();
     ActorReferenceResult::Options options = std::nullopt;
-    if (varIsSafeAcrossActors(fromModule, var, declIsolation, options) &&
+    if (varIsSafeAcrossActors(fromModule, var, declIsolation, std::nullopt, options) &&
         var->getTypeInContext()->isSendableType())
       return ActorIsolation::forNonisolated(/*unsafe*/false);
 
@@ -6869,8 +6874,8 @@ bool swift::isAccessibleAcrossActors(
   // 'let' declarations are immutable, so some of them can be accessed across
   // actors.
   if (auto var = dyn_cast<VarDecl>(value)) {
-    return varIsSafeAcrossActors(
-        fromDC->getParentModule(), var, isolation, options);
+    return varIsSafeAcrossActors(fromDC->getParentModule(), var, isolation,
+                                 actorInstance, options);
   }
 
   return false;

lib/Sema/TypeCheckDistributed.cpp

@@ -727,6 +727,11 @@ void TypeChecker::checkDistributedActor(SourceFile *SF, NominalTypeDecl *nominal
 
     // --- Ensure 'distributed func' all thunks
     if (auto func = dyn_cast<AbstractFunctionDecl>(member)) {
+      if (auto dtor = dyn_cast<DestructorDecl>(func)) {
+        ASTContext &C = dtor->getASTContext();
+        auto selfDecl = dtor->getImplicitSelfDecl();
+        selfDecl->getAttrs().add(new (C) KnownToBeLocalAttr(true));
+      }
       if (!func->isDistributed())
         continue;