[Concurrency] Global actors

include/swift/AST/ActorIsolation.h

@@ -24,6 +24,11 @@ class raw_ostream;
 
 namespace swift {
 class ClassDecl;
+class Type;
+
+/// Determine whether the given types are (canonically) equal, declared here
+/// to avoid having to include Types.h.
+bool areTypesEqual(Type type1, Type type2);
 
 /// Describes the actor isolation of a given declaration, which determines
 /// the actors with which it can interact.
@@ -37,20 +42,26 @@ class ActorIsolation {
     /// For example, a mutable stored property or synchronous function within
     /// the actor is isolated to the instance of that actor.
     ActorInstance,
-    /// The declaration can refer to actor-isolated state, but can also be
-    //// referenced from outside the actor.
-    ActorPrivileged,
     /// The declaration is explicitly specified to be independent of any actor,
     /// meaning that it can be used from any actor but is also unable to
     /// refer to the isolated state of any given actor.
     Independent,
+    /// The declaration is isolated to a global actor. It can refer to other
+    /// entities with the same global actor.
+    GlobalActor,
   };
 
 private:
   Kind kind;
-  ClassDecl *actor;
+  union {
+    ClassDecl *actor;
+    Type globalActor;
+    void *pointer;
+  };
 
   ActorIsolation(Kind kind, ClassDecl *actor) : kind(kind), actor(actor) { }
+  ActorIsolation(Kind kind, Type globalActor)
+      : kind(kind), globalActor(globalActor) { }
 
 public:
   static ActorIsolation forUnspecified() {
@@ -61,23 +72,28 @@ class ActorIsolation {
     return ActorIsolation(Independent, nullptr);
   }
 
-  static ActorIsolation forActorPrivileged(ClassDecl *actor) {
-    return ActorIsolation(ActorPrivileged, actor);
-  }
-
   static ActorIsolation forActorInstance(ClassDecl *actor) {
     return ActorIsolation(ActorInstance, actor);
   }
 
+  static ActorIsolation forGlobalActor(Type globalActor) {
+    return ActorIsolation(GlobalActor, globalActor);
+  }
+
   Kind getKind() const { return kind; }
 
   operator Kind() const { return getKind(); }
 
   ClassDecl *getActor() const {
-    assert(getKind() == ActorInstance || getKind() == ActorPrivileged);
+    assert(getKind() == ActorInstance);
     return actor;
   }
 
+  Type getGlobalActor() const {
+    assert(getKind() == GlobalActor);
+    return globalActor;
+  }
+
   friend bool operator==(const ActorIsolation &lhs,
                          const ActorIsolation &rhs) {
     if (lhs.kind != rhs.kind)
@@ -89,8 +105,10 @@ class ActorIsolation {
       return true;
 
     case ActorInstance:
-    case ActorPrivileged:
       return lhs.actor == rhs.actor;
+
+    case GlobalActor:
+      return areTypesEqual(lhs.globalActor, rhs.globalActor);
     }
   }
 
@@ -100,7 +118,7 @@ class ActorIsolation {
   }
 
   friend llvm::hash_code hash_value(const ActorIsolation &state) {
-    return llvm::hash_combine(state.kind, state.actor);
+    return llvm::hash_combine(state.kind, state.pointer);
   }
 };
 

include/swift/AST/Attr.def

@@ -578,6 +578,12 @@ SIMPLE_DECL_ATTR(actorIndependent, ActorIndependent,
   APIStableToAdd | APIBreakingToRemove,
   103)
 
+SIMPLE_DECL_ATTR(globalActor, GlobalActor,
+  OnClass | OnStruct | OnEnum | ConcurrencyOnly |
+  ABIStableToAdd | ABIBreakingToRemove |
+  APIStableToAdd | APIBreakingToRemove,
+  104)
+
 #undef TYPE_ATTR
 #undef DECL_ATTR_ALIAS
 #undef CONTEXTUAL_DECL_ATTR_ALIAS

include/swift/AST/Decl.h

@@ -950,6 +950,18 @@ class alignas(1 << DeclAlignInBits) Decl {
   /// If this returns true, the decl can be safely casted to ValueDecl.
   bool isPotentiallyOverridable() const;
 
+  /// Returns true if this Decl cannot be seen by any other source file
+  bool isPrivateToEnclosingFile() const;
+
+  /// Retrieve the global actor attribute that applies to this declaration,
+  /// if any.
+  ///
+  /// This is the "raw" global actor attribute as written directly on the
+  /// declaration, along with the nominal type declaration to which it refers,
+  /// without any inference rules applied.
+  Optional<std::pair<CustomAttr *, NominalTypeDecl *>>
+  getGlobalActorAttr() const;
+
   /// If an alternative module name is specified for this decl, e.g. using
   /// @_originalDefinedIn attribute, this function returns this module name.
   StringRef getAlternateModuleName() const;
@@ -3172,6 +3184,20 @@ class NominalTypeDecl : public GenericTypeDecl, public IterableDeclContext {
 
   void synthesizeSemanticMembersIfNeeded(DeclName member);
 
+  /// Retrieves the static 'shared' property of a global actor type, which
+  /// is used to extract the actor instance.
+  ///
+  /// \returns the static 'shared' property for a global actor, or \c nullptr
+  /// for types that are not global actors.
+  VarDecl *getGlobalActorInstance() const;
+
+  /// Whether this type is a global actor, which can be used as an
+  /// attribute to decorate declarations for inclusion in the actor-isolated
+  /// state denoted by this type.
+  bool isGlobalActor() const {
+    return getGlobalActorInstance() != nullptr;
+  }
+
   // Implement isa/cast/dyncast/etc.
   static bool classof(const Decl *D) {
     return D->getKind() >= DeclKind::First_NominalTypeDecl &&

include/swift/AST/DiagnosticsSema.def

@@ -4153,6 +4153,21 @@ ERROR(actor_isolated_self_independent_context,none,
         "actor-isolated %0 %1 can not be referenced from an "
         "'@actorIndependent' context",
         (DescriptiveDeclKind, DeclName))
+ERROR(actor_isolated_global_actor_context,none,
+      "actor-isolated %0 %1 can not be referenced from context of global "
+      "actor %2",
+      (DescriptiveDeclKind, DeclName, Type))
+ERROR(global_actor_from_instance_actor_context,none,
+      "%0 %1 isolated to global actor %2 can not be referenced from actor %3",
+      (DescriptiveDeclKind, DeclName, Type, DeclName))
+ERROR(global_actor_from_other_global_actor_context,none,
+      "%0 %1 isolated to global actor %2 can not be referenced from "
+      "different global actor %3",
+      (DescriptiveDeclKind, DeclName, Type, Type))
+ERROR(global_actor_from_independent_context,none,
+      "%0 %1 isolated to global actor %2 can not be referenced from an "
+      "'@actorIndependent' context",
+      (DescriptiveDeclKind, DeclName, Type))
 ERROR(actor_isolated_partial_apply,none,
         "actor-isolated %0 %1 can not be partially applied",
         (DescriptiveDeclKind, DeclName))
@@ -4205,6 +4220,36 @@ ERROR(enqueue_partial_task_not_in_context,none,
       "'enqueue(partialTask:)' can only be implemented in the definition of "
       "actor class %0", (Type))
 
+ERROR(global_actor_missing_shared,none,
+      "global actor %0 requires a static property 'shared' that produces an "
+      "actor instance", (Identifier))
+NOTE(global_actor_shared_not_static,none,
+     "'shared' property in global actor is not 'static'", ())
+NOTE(global_actor_shared_inaccessible,none,
+     "'shared' property has more restrictive access (%0) than its global actor "
+     "(%1)",
+     (StringRef, StringRef))
+NOTE(global_actor_shared_constrained_extension,none,
+     "'shared' property in global actor cannot be in a constrained extension",
+     ())
+NOTE(global_actor_shared_non_actor_type,none,
+     "'shared' property type %0 does not conform to the 'Actor' protocol",
+     (Type))
+
+ERROR(multiple_global_actors,none,
+      "declaration can not have multiple global actor attributes (%0 and %1)",
+      (Identifier, Identifier))
+ERROR(global_actor_disallowed,none,
+      "%0 cannot have a global actor", (DescriptiveDeclKind))
+ERROR(global_actor_on_actor_class,none,
+      "actor class %0 cannot have a global actor", (Identifier))
+ERROR(global_actor_on_local_variable,none,
+      "local variable %0 cannot have a global actor", (DeclName))
+
+ERROR(actor_isolation_multiple_attr,none,
+      "%0 %1 has multiple actor-isolation attributes ('%2' and '%3')",
+      (DescriptiveDeclKind, DeclName, StringRef, StringRef))
+
 //------------------------------------------------------------------------------
 // MARK: Type Check Types
 //------------------------------------------------------------------------------

include/swift/AST/KnownIdentifiers.def

@@ -119,6 +119,7 @@ IDENTIFIER(Selector)
 IDENTIFIER(self)
 IDENTIFIER(Self)
 IDENTIFIER(setObject)
+IDENTIFIER(shared)
 IDENTIFIER(simd)
 IDENTIFIER(storage)
 IDENTIFIER(stringValue)

include/swift/AST/TypeCheckRequests.h

@@ -858,6 +858,55 @@ class IsActorRequest :
   bool isCached() const { return true; }
 };
 
+/// Retrieve the static "shared" property within a global actor that provides
+/// the actor instance representing the global actor.
+///
+/// Global actors can be applied to a declaration to indicate that the
+/// declaration operations on state that is protected by the global actor.
+class GlobalActorInstanceRequest :
+    public SimpleRequest<GlobalActorInstanceRequest,
+                         VarDecl *(NominalTypeDecl *),
+                         RequestFlags::Cached> {
+public:
+  using SimpleRequest::SimpleRequest;
+
+private:
+  friend SimpleRequest;
+
+  VarDecl *evaluate(Evaluator &evaluator, NominalTypeDecl *nominal) const;
+
+public:
+  // Caching
+  bool isCached() const { return true; }
+};
+
+using CustomAttrNominalPair = std::pair<CustomAttr *, NominalTypeDecl *>;
+
+/// Request the custom attribute which denotes the global actor for the given
+/// declaration.
+///
+/// This is the "raw" global actor attribute as written directly on the
+/// declaration, with any inference rules applied.
+class GlobalActorAttributeRequest :
+    public SimpleRequest<
+        GlobalActorAttributeRequest,
+        Optional<CustomAttrNominalPair>(Decl *),
+        RequestFlags::Cached> {
+public:
+  using SimpleRequest::SimpleRequest;
+
+private:
+  friend SimpleRequest;
+
+  // Evaluation.
+  Optional<std::pair<CustomAttr *, NominalTypeDecl *>>
+  evaluate(Evaluator &evaluator, Decl *decl) const;
+
+public:
+  // Caching
+  bool isCached() const { return true; }
+};
+
 /// Determine the actor isolation for the given declaration.
 class ActorIsolationRequest :
     public SimpleRequest<ActorIsolationRequest,

include/swift/AST/TypeCheckerTypeIDZone.def

@@ -87,6 +87,12 @@ SWIFT_REQUEST(TypeChecker, CanBeAsyncHandlerRequest, bool(FuncDecl *),
               Cached, NoLocationInfo)
 SWIFT_REQUEST(TypeChecker, IsActorRequest, bool(ClassDecl *),
               Cached, NoLocationInfo)
+SWIFT_REQUEST(TypeChecker, GlobalActorInstanceRequest,
+              VarDecl *(NominalTypeDecl *),
+              Cached, NoLocationInfo)
+SWIFT_REQUEST(TypeChecker, GlobalActorAttributeRequest,
+              Optional<CustomAttrNominalPair>(Decl *),
+              Cached, NoLocationInfo)
 SWIFT_REQUEST(TypeChecker, ActorIsolationRequest,
               ActorIsolationState(ValueDecl *),
               Cached, NoLocationInfo)

include/swift/Basic/CTypeIDZone.def

@@ -38,7 +38,9 @@ SWIFT_TYPEID_NAMED(std::string, String)
 SWIFT_TYPEID_NAMED(evaluator::SideEffect, SideEffect)
 SWIFT_TYPEID_TEMPLATE1_NAMED(std::vector, Vector, typename T, T)
 SWIFT_TYPEID_TEMPLATE1_NAMED(std::unique_ptr, UniquePtr, typename T, T)
+SWIFT_TYPEID_TEMPLATE2_NAMED(std::pair, Pair, typename T1, T1, typename T2, T2)
 
 // LLVM ADT types.
 SWIFT_TYPEID_TEMPLATE1_NAMED(llvm::TinyPtrVector, TinyPtrVector, typename T, T)
 SWIFT_TYPEID_TEMPLATE1_NAMED(llvm::ArrayRef, ArrayRef, typename T, T)
+SWIFT_TYPEID_TEMPLATE1_NAMED(llvm::Optional, Optional, typename T, T)

include/swift/Basic/DefineTypeIDZone.h

@@ -40,9 +40,11 @@ template<> struct TypeIDZoneTypes<Zone::SWIFT_TYPEID_ZONE> {
   enum Types : uint8_t {
 #define SWIFT_TYPEID_NAMED(Type, Name) Name,
 #define SWIFT_TYPEID_TEMPLATE1_NAMED(Template, Name, Param1, Arg1) Name,
+#define SWIFT_TYPEID_TEMPLATE2_NAMED(Template, Name, Param1, Arg1, Param2, Arg2) Name,
 #include SWIFT_TYPEID_HEADER
 #undef SWIFT_TYPEID_NAMED
 #undef SWIFT_TYPEID_TEMPLATE1_NAMED
+#undef SWIFT_TYPEID_TEMPLATE2_NAMED
   };
 };
 
@@ -77,12 +79,34 @@ public:                                                               \
                                                                       \
 template<Param1> const uint64_t TypeID<Template<Arg1>>::value;
 
+#define SWIFT_TYPEID_TEMPLATE2_NAMED(Template, Name, Param1, Arg1, Param2, Arg2) \
+template<Param1, Param2> struct TypeID<Template<Arg1, Arg2>> {        \
+private:                                                              \
+  static const uint64_t templateID =                                  \
+    formTypeID(static_cast<uint8_t>(Zone::SWIFT_TYPEID_ZONE),         \
+               TypeIDZoneTypes<Zone::SWIFT_TYPEID_ZONE>::Name);       \
+                                                                      \
+public:                                                               \
+  static const uint64_t value =                                       \
+    (TypeID<Arg1>::value << 32) |                                     \
+    (TypeID<Arg2>::value << 16) |                                     \
+    templateID;                                                       \
+                                                                      \
+  static std::string getName() {                                      \
+    return std::string(#Name) + "<" + TypeID<Arg1>::getName() +       \
+        ", " + TypeID<Arg2>::getName() + ">";                         \
+  }                                                                   \
+};                                                                    \
+                                                                      \
+template<Param1, Param2> const uint64_t TypeID<Template<Arg1, Arg2>>::value;
+
 #include SWIFT_TYPEID_HEADER
 
 #undef SWIFT_REQUEST
 
 #undef SWIFT_TYPEID_NAMED
 #undef SWIFT_TYPEID_TEMPLATE1_NAMED
+#undef SWIFT_TYPEID_TEMPLATE2_NAMED
 
 #undef SWIFT_TYPEID
 #undef SWIFT_TYPEID_ZONE

include/swift/Basic/SimpleDisplay.h

@@ -23,6 +23,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include <tuple>
 #include <type_traits>
+#include <utility>
 
 namespace swift {
   template<typename T>
@@ -93,7 +94,17 @@ namespace swift {
                       const std::tuple<Types...> &value) {
     simple_display_tuple<0>(out, value);
   }
-
+
+  template<typename T1, typename T2>
+  void simple_display(llvm::raw_ostream &out,
+                      const std::pair<T1, T2> &value) {
+    out << "(";
+    simple_display(out, value.first);
+    out << ", ";
+    simple_display(out, value.second);
+    out << ")";
+  }
+
   template<typename T>
   void simple_display(llvm::raw_ostream &out,
                       const llvm::TinyPtrVector<T> &vector) {

lib/AST/Decl.cpp

@@ -672,6 +672,14 @@ static_assert(sizeof(checkSourceLocType(&ID##Decl::getLoc)) == 2, \
   llvm_unreachable("invalid file kind");
 }
 
+Optional<CustomAttrNominalPair> Decl::getGlobalActorAttr() const {
+  auto &ctx = getASTContext();
+  auto mutableThis = const_cast<Decl *>(this);
+  return evaluateOrDefault(ctx.evaluator,
+                           GlobalActorAttributeRequest{mutableThis},
+                           None);
+}
+
 Expr *AbstractFunctionDecl::getSingleExpressionBody() const {
   assert(hasSingleExpressionBody() && "Not a single-expression body");
   auto braceStmt = getBody();
@@ -4044,6 +4052,13 @@ void NominalTypeDecl::synthesizeSemanticMembersIfNeeded(DeclName member) {
   }
 }
 
+VarDecl *NominalTypeDecl::getGlobalActorInstance() const {
+  auto mutableThis = const_cast<NominalTypeDecl *>(this);
+  return evaluateOrDefault(getASTContext().evaluator,
+                           GlobalActorInstanceRequest{mutableThis},
+                           nullptr);
+}
+
 ClassDecl::ClassDecl(SourceLoc ClassLoc, Identifier Name, SourceLoc NameLoc,
                      MutableArrayRef<TypeLoc> Inherited,
                      GenericParamList *GenericParams, DeclContext *Parent)