Remove Actor.enqueue(partialTask:) and all its magic.

The backs out of some early decisions we made about actor layout
that we don't need. Custom actors will use a different approach.

This should suffice for the remainder of rdar://70146827.

Author: DougGregor

include/swift/ABI/MetadataValues.h

@@ -1173,9 +1173,6 @@ namespace SpecialPointerAuthDiscriminators {
   /// Resilient class stub initializer callback
   const uint16_t ResilientClassStubInitCallback = 0xC671;
 
-  /// Actor enqueue(partialTask:).
-  const uint16_t ActorEnqueuePartialTask = 0x8f3d;
-
   /// Jobs, tasks, and continuations.
   const uint16_t JobInvokeFunction = 0xcc64; // = 52324
   const uint16_t TaskResumeFunction = 0x2c42; // = 11330

include/swift/AST/Decl.h

@@ -3940,7 +3940,6 @@ enum class KnownDerivableProtocolKind : uint8_t {
   Decodable,
   AdditiveArithmetic,
   Differentiable,
-  Actor,
 };
 
 /// ProtocolDecl - A declaration of a protocol, for example:
@@ -6159,14 +6158,6 @@ 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

@@ -4412,10 +4412,6 @@ ERROR(concurrency_lib_missing,none,
 ERROR(async_main_no_concurrency,none,
       "'_Concurrency' module not imported, required for async main", ())
 
-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))

include/swift/AST/KnownIdentifiers.def

@@ -117,8 +117,6 @@ IDENTIFIER(oldValue)
 IDENTIFIER(Optional)
 IDENTIFIER_(OptionalNilComparisonType)
 IDENTIFIER(parameter)
-IDENTIFIER(partialTask)
-IDENTIFIER(PartialAsyncTask)
 IDENTIFIER(projected)
 IDENTIFIER(projectedValue)
 IDENTIFIER(Protocol)
@@ -220,7 +218,6 @@ IDENTIFIER(className)
 
 IDENTIFIER(_defaultActorInitialize)
 IDENTIFIER(_defaultActorDestroy)
-IDENTIFIER(_defaultActorEnqueue)
 
 IDENTIFIER_(ErrorType)
 IDENTIFIER(Code)

lib/AST/Decl.cpp

@@ -5083,8 +5083,6 @@ Optional<KnownDerivableProtocolKind>
     return KnownDerivableProtocolKind::AdditiveArithmetic;
   case KnownProtocolKind::Differentiable:
     return KnownDerivableProtocolKind::Differentiable;
-  case KnownProtocolKind::Actor:
-    return KnownDerivableProtocolKind::Actor;
   default: return None;
   }
 }
@@ -7559,56 +7557,6 @@ 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,
@@ -8003,17 +7951,6 @@ Type TypeBase::getSwiftNewtypeUnderlyingType() {
 }
 
 bool ClassDecl::hasExplicitCustomActorMethods() const {
-  auto &ctx = getASTContext();
-  for (auto member: getMembers()) {
-    if (member->isImplicit()) continue;
-
-    // Methods called enqueue(partialTask:)
-    if (auto func = dyn_cast<FuncDecl>(member)) {
-      if (FuncDecl::isEnqueuePartialTaskName(ctx, func->getName()))
-        return true;
-    }
-  }
-
   return false;
 }
 

lib/IRGen/GenPointerAuth.cpp

@@ -400,17 +400,6 @@ 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 discriminator, 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

@@ -18,7 +18,6 @@ add_swift_host_library(swiftSema STATIC
   ConstraintLocator.cpp
   ConstraintSystem.cpp
   DebuggerTestingTransform.cpp
-  DerivedConformanceActor.cpp
   DerivedConformanceAdditiveArithmetic.cpp
   DerivedConformanceCaseIterable.cpp
   DerivedConformanceCodable.cpp

lib/Sema/DerivedConformanceActor.cpp

@@ -75,10 +75,6 @@ bool DerivedConformance::derivesProtocolConformance(DeclContext *DC,
     return canDeriveHashable(Nominal);
   }
 
-  if (*derivableKind == KnownDerivableProtocolKind::Actor) {
-    return canDeriveActor(Nominal, DC);
-  }
-
   if (*derivableKind == KnownDerivableProtocolKind::AdditiveArithmetic)
     return canDeriveAdditiveArithmetic(Nominal, DC);
 
@@ -350,11 +346,6 @@ ValueDecl *DerivedConformance::getDerivableRequirement(NominalTypeDecl *nominal,
         return getRequirement(KnownProtocolKind::Hashable);
     }
 
-    // Actor.enqueue(partialTask: PartialTask)
-    if (FuncDecl::isEnqueuePartialTaskName(ctx, name)) {
-      return getRequirement(KnownProtocolKind::Actor);
-    }
-
     return nullptr;
   }
 

lib/Sema/DerivedConformances.cpp

@@ -298,14 +298,6 @@ class DerivedConformance {
   /// \returns the derived member, which will also be added to the type.
   ValueDecl *deriveDecodable(ValueDecl *requirement);
 
-  /// Whether we can derive the given Actor requirement in the given context.
-  static bool canDeriveActor(NominalTypeDecl *nominal, DeclContext *dc);
-
-  /// Derive an Actor requirement for an actor class.
-  ///
-  /// \returns the derived member, which will also be added to the type.
-  ValueDecl *deriveActor(ValueDecl *requirement);
-
   /// Declare a read-only property.
   std::pair<VarDecl *, PatternBindingDecl *>
   declareDerivedProperty(Identifier name, Type propertyInterfaceType,