Distributed actor isolation

docs/ReferenceGuides/UnderscoredAttributes.md

@@ -113,14 +113,6 @@ library), instead of at an arbitrary point in time.
 For more details, see the forum post on
 [dynamic method replacement](https://forums.swift.org/t/dynamic-method-replacement/16619).
 
-## `@_distributedActorIndependent`
-
-Marks a specific property of a distributed actor to be available even if the
-actor is remote.
-
-This only applies to two distributed actor properties `address` and `transport`.
-It cannot be safely declared on any properties defined by ordinary Swift code.
-
 ## `@_effects(effectname)`
 
 Tells the compiler that the implementation of the defined function is limited

include/swift/AST/Attr.def

@@ -658,12 +658,7 @@ CONTEXTUAL_SIMPLE_DECL_ATTR(distributed, DistributedActor,
   APIBreakingToAdd | APIBreakingToRemove,
   118)
 
-SIMPLE_DECL_ATTR(_distributedActorIndependent, DistributedActorIndependent,
-  OnFunc | OnVar |
-  DistributedOnly | UserInaccessible |
-  ABIStableToAdd | ABIStableToRemove |
-  APIBreakingToAdd | APIBreakingToRemove,
-  119)
+// 119 is unused
 
 SIMPLE_DECL_ATTR(_assemblyVision, EmitAssemblyVisionRemarks,
   OnFunc | UserInaccessible | NotSerialized | OnNominalType |

include/swift/AST/Decl.h

@@ -2391,8 +2391,6 @@ class ValueDecl : public Decl {
   /// Is this declaration marked with 'dynamic'?
   bool isDynamic() const;
 
-  bool isDistributedActorIndependent() const;
-
 private:
   bool isObjCDynamic() const {
     return isObjC() && isDynamic();
@@ -4790,8 +4788,6 @@ class AbstractStorageDecl : public ValueDecl {
 
   bool hasAnyNativeDynamicAccessors() const;
 
-  bool isDistributedActorIndependent() const;
-
   // Implement isa/cast/dyncast/etc.
   static bool classof(const Decl *D) {
     return D->getKind() >= DeclKind::First_AbstractStorageDecl &&

include/swift/AST/DiagnosticsSema.def

@@ -4616,9 +4616,6 @@ ERROR(distributed_actor_user_defined_special_property,none,
       "property %0 cannot be defined explicitly, as it conflicts with "
       "distributed actor synthesized stored property",
       (DeclName))
-ERROR(distributed_actor_independent_property_must_be_let,none,
-      "_distributedActorIndependent can be applied to properties, however they must be 'let'",
-      ())
 NOTE(distributed_actor_isolated_property,none,
       "distributed actor state is only available within the actor instance", // TODO: reword in terms of isolation
       ())

include/swift/AST/Expr.h

@@ -4338,6 +4338,7 @@ class ApplyExpr : public Expr {
     Bits.ApplyExpr.ImplicitlyAsync = false;
     Bits.ApplyExpr.ImplicitlyThrows = false;
     Bits.ApplyExpr.NoAsync = false;
+    Bits.ApplyExpr.ShouldApplyDistributedThunk = false;
   }
 
 public:

lib/AST/Decl.cpp

@@ -2934,10 +2934,6 @@ bool ValueDecl::isDynamic() const {
     getAttrs().hasAttribute<DynamicAttr>());
 }
 
-bool ValueDecl::isDistributedActorIndependent() const {
-  return getAttrs().hasAttribute<DistributedActorIndependentAttr>();
-}
-
 bool ValueDecl::isObjCDynamicInGenericClass() const {
   if (!isObjCDynamic())
     return false;
@@ -5371,10 +5367,6 @@ bool AbstractStorageDecl::hasAnyNativeDynamicAccessors() const {
   return false;
 }
 
-bool AbstractStorageDecl::isDistributedActorIndependent() const {
-  return getAttrs().hasAttribute<DistributedActorIndependentAttr>();
-}
-
 void AbstractStorageDecl::setAccessors(SourceLoc lbraceLoc,
                                        ArrayRef<AccessorDecl *> accessors,
                                        SourceLoc rbraceLoc) {

lib/SILGen/SILGenDistributed.cpp

@@ -817,7 +817,7 @@ void SILGenFunction::emitDistributedActorClassMemberDestruction(
     B.emitBlock(remoteMemberDestroyBB);
 
     for (VarDecl *vd : cd->getStoredProperties()) {
-      if (!vd->getAttrs().hasAttribute<DistributedActorIndependentAttr>())
+      if (getActorIsolation(vd) == ActorIsolation::DistributedActorInstance)
         continue;
 
       destroyClassMember(cleanupLoc, selfValue, vd);

lib/Sema/CodeSynthesisDistributedActor.cpp

@@ -172,9 +172,8 @@ AbstractFunctionDecl *TypeChecker::addImplicitDistributedActorRemoteFunction(
   remoteFuncDecl->getAttrs().add(
       new (C) DynamicAttr(/*implicit=*/true));
 
-  // @_distributedActorIndependent
-  remoteFuncDecl->getAttrs().add(
-      new (C) DistributedActorIndependentAttr(/*IsImplicit=*/true));
+  // nonisolated
+  remoteFuncDecl->getAttrs().add(new (C) NonisolatedAttr(/*IsImplicit=*/true));
 
   // users should never have to access this function directly;
   // it is only invoked from our distributed function thunk if the actor is remote.

lib/Sema/DerivedConformanceDistributedActor.cpp

@@ -105,7 +105,7 @@ static ValueDecl *deriveDistributedActor_id(DerivedConformance &derived) {
   auto &C = derived.Context;
 
   // ```
-  // @_distributedActorIndependent
+  // nonisolated
   // let id: AnyActorIdentity
   // ```
   auto propertyType = C.getAnyActorIdentityDecl()->getDeclaredInterfaceType();
@@ -119,9 +119,9 @@ static ValueDecl *deriveDistributedActor_id(DerivedConformance &derived) {
 
   propDecl->setIntroducer(VarDecl::Introducer::Let);
 
-  // mark as @_distributedActorIndependent, allowing access to it from everywhere
+  // mark as nonisolated, allowing access to it from everywhere
   propDecl->getAttrs().add(
-      new (C) DistributedActorIndependentAttr(/*IsImplicit=*/true));
+      new (C) NonisolatedAttr(/*IsImplicit=*/true));
 
   derived.addMembersToConformanceContext({ propDecl, pbDecl });
   return propDecl;
@@ -133,7 +133,7 @@ static ValueDecl *deriveDistributedActor_actorTransport(
   auto &C = derived.Context;
 
   // ```
-  // @_distributedActorIndependent
+  // nonisolated
   // let actorTransport: ActorTransport
   // ```
   // (no need for @actorIndependent because it is an immutable let)
@@ -148,9 +148,9 @@ static ValueDecl *deriveDistributedActor_actorTransport(
 
   propDecl->setIntroducer(VarDecl::Introducer::Let);
 
-  // mark as @_distributedActorIndependent, allowing access to it from everywhere
+  // mark as nonisolated, allowing access to it from everywhere
   propDecl->getAttrs().add(
-      new (C) DistributedActorIndependentAttr(/*IsImplicit=*/true));
+      new (C) NonisolatedAttr(/*IsImplicit=*/true));
 
   derived.addMembersToConformanceContext({ propDecl, pbDecl });
   return propDecl;

lib/Sema/TypeCheckAttr.cpp

@@ -256,7 +256,6 @@ class AttributeChecker : public AttributeVisitor<AttributeChecker> {
 
   void visitActorAttr(ActorAttr *attr);
   void visitDistributedActorAttr(DistributedActorAttr *attr);
-  void visitDistributedActorIndependentAttr(DistributedActorIndependentAttr *attr);
   void visitGlobalActorAttr(GlobalActorAttr *attr);
   void visitAsyncAttr(AsyncAttr *attr);
   void visitMarkerAttr(MarkerAttr *attr);
@@ -5400,7 +5399,7 @@ void AttributeChecker::visitActorAttr(ActorAttr *attr) {
 void AttributeChecker::visitDistributedActorAttr(DistributedActorAttr *attr) {
   auto dc = D->getDeclContext();
 
-  // distributed can be applied to actor class definitions and async functions
+  // distributed can be applied to actor definitions and their methods
   if (auto varDecl = dyn_cast<VarDecl>(D)) {
     // distributed can not be applied to stored properties
     diagnoseAndRemoveAttr(attr, diag::distributed_actor_property);
@@ -5473,7 +5472,13 @@ void AttributeChecker::visitNonisolatedAttr(NonisolatedAttr *attr) {
       // distributed actors. Attempts of nonisolated access would be
       // cross-actor, and that means they might be accessing on a remote actor,
       // in which case the stored property storage does not exist.
-      if (nominal && nominal->isDistributedActor()) {
+      //
+      // The synthesized "id" and "actorTransport" are the only exceptions,
+      // because the implementation mirrors them.
+      if (nominal && nominal->isDistributedActor() &&
+          !(var->isImplicit() &&
+            (var->getName() == Ctx.Id_id ||
+             var->getName() == Ctx.Id_actorTransport))) {
         diagnoseAndRemoveAttr(attr,
                               diag::nonisolated_distributed_actor_storage);
         return;
@@ -5504,16 +5509,6 @@ void AttributeChecker::visitNonisolatedAttr(NonisolatedAttr *attr) {
   }
 }
 
-void AttributeChecker::visitDistributedActorIndependentAttr(DistributedActorIndependentAttr *attr) {
-  /// user-inaccessible _distributedActorIndependent can only be applied to let properties
-  if (auto var = dyn_cast<VarDecl>(D)) {
-    if (!var->isLet()) {
-      diagnoseAndRemoveAttr(attr, diag::distributed_actor_independent_property_must_be_let);
-      return;
-    }
-  }
-}
-
 void AttributeChecker::visitGlobalActorAttr(GlobalActorAttr *attr) {
   auto nominal = dyn_cast<NominalTypeDecl>(D);
   if (!nominal)