[Concurrency] Introduce Actor protocol to which actor classes all conform

include/swift/ABI/MetadataValues.h

@@ -1177,6 +1177,9 @@ namespace SpecialPointerAuthDiscriminators {
 
   /// Resilient class stub initializer callback
   const uint16_t ResilientClassStubInitCallback = 0xC671;
+
+  /// Actor enqueue(partialTask:).
+  const uint16_t ActorEnqueuePartialTask = 0x8f3d;
 }
 
 /// The number of arguments that will be passed directly to a generic

include/swift/AST/Attr.def

@@ -567,7 +567,7 @@ SIMPLE_DECL_ATTR(asyncHandler, AsyncHandler,
   101)
 
 CONTEXTUAL_SIMPLE_DECL_ATTR(actor, Actor,
-  OnClass | ConcurrencyOnly |
+  DeclModifier | OnClass | ConcurrencyOnly |
   ABIBreakingToAdd | ABIBreakingToRemove |
   APIBreakingToAdd | APIBreakingToRemove,
   102)

include/swift/AST/Decl.h

@@ -4175,6 +4175,7 @@ enum class KnownDerivableProtocolKind : uint8_t {
   Decodable,
   AdditiveArithmetic,
   Differentiable,
+  Actor,
 };
 
 /// ProtocolDecl - A declaration of a protocol, for example:
@@ -6328,6 +6329,14 @@ class FuncDecl : public AbstractFunctionDecl {
 
   bool isMainTypeMainMethod() const;
 
+  /// Whether the given name is enqueue(partialTask:), which is used for
+  /// actors.
+  static bool isEnqueuePartialTaskName(ASTContext &ctx, DeclName name);
+
+  /// Determine whether this function is the witness to the Actor protocol's
+  /// enqueue(partialTask:) operation within an actor.
+  bool isActorEnqueuePartialTaskWitness() const;
+
   SelfAccessKind getSelfAccessKind() const;
 
   void setSelfAccessKind(SelfAccessKind mod) {

include/swift/AST/DiagnosticsSema.def

@@ -4101,6 +4101,9 @@ ERROR(not_objc_function_async,none,
       "'async' function cannot be represented in Objective-C", ())
 NOTE(not_objc_function_type_async,none,
       "'async' function types cannot be represented in Objective-C", ())
+ERROR(actor_isolated_objc,none,
+      "actor-isolated %0 %1 cannot be @objc",
+       (DescriptiveDeclKind, DeclName))
 NOTE(protocol_witness_async_conflict,none,
      "candidate is %select{not |}0'async', but protocol requirement is%select{| not}0",
      (bool))
@@ -4195,6 +4198,13 @@ ERROR(actorisolated_not_actor_instance_member,none,
       "'@actorIsolated' can only be applied to instance members of actors",
       ())
 
+ERROR(concurrency_lib_missing,none,
+      "missing '%0' declaration, probably because the '_Concurrency' "
+      "module was not imported", (StringRef))
+ERROR(enqueue_partial_task_not_in_context,none,
+      "'enqueue(partialTask:)' can only be implemented in the definition of "
+      "actor class %0", (Type))
+
 //------------------------------------------------------------------------------
 // MARK: Type Check Types
 //------------------------------------------------------------------------------

include/swift/AST/KnownIdentifiers.def

@@ -44,6 +44,7 @@ IDENTIFIER(Change)
 IDENTIFIER_WITH_NAME(code_, "_code")
 IDENTIFIER(CodingKeys)
 IDENTIFIER(combine)
+IDENTIFIER_(Concurrency)
 IDENTIFIER(container)
 IDENTIFIER(CoreGraphics)
 IDENTIFIER(CoreMedia)
@@ -67,6 +68,7 @@ IDENTIFIER(encode)
 IDENTIFIER(encodeIfPresent)
 IDENTIFIER(Encoder)
 IDENTIFIER(encoder)
+IDENTIFIER(enqueue)
 IDENTIFIER(erasing)
 IDENTIFIER(error)
 IDENTIFIER(errorDomain)
@@ -105,6 +107,8 @@ IDENTIFIER(oldValue)
 IDENTIFIER(Optional)
 IDENTIFIER_(OptionalNilComparisonType)
 IDENTIFIER(parameter)
+IDENTIFIER(partialTask)
+IDENTIFIER(PartialAsyncTask)
 IDENTIFIER(projected)
 IDENTIFIER(projectedValue)
 IDENTIFIER(Protocol)
@@ -137,6 +141,7 @@ IDENTIFIER(withKeywordArguments)
 IDENTIFIER(wrapped)
 IDENTIFIER(wrappedValue)
 IDENTIFIER(wrapperValue)
+IDENTIFIER_WITH_NAME(actorStorage, "$__actor_storage")
 
 // Kinds of layout constraints
 IDENTIFIER_WITH_NAME(UnknownLayout, "_UnknownLayout")

include/swift/AST/KnownProtocols.def

@@ -58,6 +58,7 @@
 #define BUILTIN_EXPRESSIBLE_BY_LITERAL_PROTOCOL_(name) \
     BUILTIN_EXPRESSIBLE_BY_LITERAL_PROTOCOL_WITH_NAME(name, "_" #name)
 
+PROTOCOL(Actor)
 PROTOCOL(Sequence)
 PROTOCOL(IteratorProtocol)
 PROTOCOL(RawRepresentable)

lib/AST/ASTContext.cpp

@@ -947,6 +947,9 @@ ProtocolDecl *ASTContext::getProtocol(KnownProtocolKind kind) const {
   case KnownProtocolKind::Differentiable:
     M = getLoadedModule(Id_Differentiation);
     break;
+  case KnownProtocolKind::Actor:
+    M = getLoadedModule(Id_Concurrency);
+    break;
   default:
     M = getStdlibModule();
     break;

lib/AST/Decl.cpp

@@ -5047,7 +5047,8 @@ void ProtocolDecl::computeKnownProtocolKind() const {
   auto module = getModuleContext();
   if (module != module->getASTContext().getStdlibModule() &&
       !module->getName().is("Foundation") &&
-      !module->getName().is("_Differentiation")) {
+      !module->getName().is("_Differentiation") &&
+      !module->getName().is("_Concurrency")) {
     const_cast<ProtocolDecl *>(this)->Bits.ProtocolDecl.KnownProtocol = 1;
     return;
   }
@@ -5093,6 +5094,8 @@ Optional<KnownDerivableProtocolKind>
     return KnownDerivableProtocolKind::AdditiveArithmetic;
   case KnownProtocolKind::Differentiable:
     return KnownDerivableProtocolKind::Differentiable;
+  case KnownProtocolKind::Actor:
+    return KnownDerivableProtocolKind::Actor;
   default: return None;
   }
 }
@@ -7505,6 +7508,56 @@ bool FuncDecl::isMainTypeMainMethod() const {
          getParameters()->size() == 0;
 }
 
+bool FuncDecl::isEnqueuePartialTaskName(ASTContext &ctx, DeclName name) {
+  if (name.isCompoundName() && name.getBaseName() == ctx.Id_enqueue) {
+    auto argumentNames = name.getArgumentNames();
+    return argumentNames.size() == 1 && argumentNames[0] == ctx.Id_partialTask;
+  }
+
+  return false;
+}
+
+bool FuncDecl::isActorEnqueuePartialTaskWitness() const {
+  if (!isEnqueuePartialTaskName(getASTContext(), getName()))
+    return false;
+
+  auto classDecl = getDeclContext()->getSelfClassDecl();
+  if (!classDecl)
+    return false;
+
+  if (!classDecl->isActor())
+    return false;
+
+  ASTContext &ctx = getASTContext();
+  auto actorProto = ctx.getProtocol(KnownProtocolKind::Actor);
+  if (!actorProto)
+    return false;
+
+  FuncDecl *requirement = nullptr;
+  for (auto protoMember : actorProto->getParsedMembers()) {
+    if (auto protoFunc = dyn_cast<FuncDecl>(protoMember)) {
+      if (isEnqueuePartialTaskName(ctx, protoFunc->getName())) {
+        requirement = protoFunc;
+        break;
+      }
+    }
+  }
+
+  if (!requirement)
+    return false;
+
+  SmallVector<ProtocolConformance *, 1> conformances;
+  classDecl->lookupConformance(
+      classDecl->getModuleContext(), actorProto, conformances);
+  for (auto conformance : conformances) {
+    auto witness = conformance->getWitnessDecl(requirement);
+    if (witness == this)
+      return true;
+  }
+
+  return false;
+}
+
 ConstructorDecl::ConstructorDecl(DeclName Name, SourceLoc ConstructorLoc,
                                  bool Failable, SourceLoc FailabilityLoc,
                                  bool Throws,

lib/AST/ProtocolConformance.cpp

@@ -1256,6 +1256,12 @@ void NominalTypeDecl::prepareConformanceTable() const {
       addSynthesized(KnownProtocolKind::RawRepresentable);
     }
   }
+
+  // Actor classes conform to the actor protocol.
+  if (auto classDecl = dyn_cast<ClassDecl>(mutableThis)) {
+    if (classDecl->isActor())
+      addSynthesized(KnownProtocolKind::Actor);
+  }
 }
 
 bool NominalTypeDecl::lookupConformance(

lib/IRGen/GenMeta.cpp

@@ -5045,6 +5045,7 @@ SpecialProtocol irgen::getSpecialProtocolID(ProtocolDecl *P) {
   case KnownProtocolKind::AdditiveArithmetic:
   case KnownProtocolKind::Differentiable:
   case KnownProtocolKind::FloatingPoint:
+  case KnownProtocolKind::Actor:
     return SpecialProtocol::None;
   }
 

lib/IRGen/GenPointerAuth.cpp

@@ -400,6 +400,17 @@ PointerAuthEntity::getDeclDiscriminator(IRGenModule &IGM) const {
     assert(!constant.isForeign &&
            "discriminator for foreign declaration not supported yet!");
 
+    // Special case: methods that are witnesses to Actor.enqueue(partialTask:)
+    // have their own descriminator, which is shared across all actor classes.
+    if (constant.hasFuncDecl()) {
+      auto func = dyn_cast<FuncDecl>(constant.getFuncDecl());
+      if (func->isActorEnqueuePartialTaskWitness()) {
+        cache = IGM.getSize(
+            Size(SpecialPointerAuthDiscriminators::ActorEnqueuePartialTask));
+        return cache;
+      }
+    }
+
     auto mangling = constant.mangle();
     cache = getDiscriminatorForString(IGM, mangling);
     return cache;

lib/Sema/CMakeLists.txt

@@ -17,6 +17,7 @@ add_swift_host_library(swiftSema STATIC
   ConstraintLocator.cpp
   ConstraintSystem.cpp
   DebuggerTestingTransform.cpp
+  DerivedConformanceActor.cpp
   DerivedConformanceAdditiveArithmetic.cpp
   DerivedConformanceCaseIterable.cpp
   DerivedConformanceCodable.cpp